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                                                                    EXHIBIT 99.1
                                  RISK FACTORS
 
     An investment in the shares of Common Stock offered hereby involves a high
degree of risk. The following factors, in addition to the other information
contained in this Prospectus, should be carefully considered in evaluating the
Company and its business before purchasing the shares of Common Stock offered
hereby.
 
EARLY STAGE OF DEVELOPMENT; TECHNOLOGICAL UNCERTAINTY
 
     Diatide was founded in February 1990 and is at an early stage of
development. All of the Company's potential products are in research or
development and will require additional research and development, extensive
preclinical studies and clinical trials and regulatory approval prior to any
commercial sales. The Company must successfully address a number of
technological challenges to complete certain of its development efforts. In
addition, there can be no assurance that the Company will be permitted to
undertake and complete human clinical trials of any of the Company's potential
products, either in the United States or elsewhere, or, if permitted, that such
products will be demonstrated to be safe and efficacious. In addition, there can
be no assurance that any of the Company's potential products will obtain United
States Food and Drug Administration ("FDA") or other regulatory approval for any
indication or that an approved product will be capable of being produced in
commercial quantities at reasonable cost and successfully marketed. See
"Business."
 
     The use of synthetic peptides in radiopharmaceuticals, which is central to
the Company's technology, is new to nuclear medicine. The Company is aware of
only one imaging product and no therapeutics based on this scientific approach
that have been approved for sale by the FDA. The products for which the Company
has submitted or currently plans to submit investigational new drug ("IND")
applications and all of the Company's other potential products in research or
development may prove to have undesirable and unintended side effects in humans
or other characteristics that may prevent or limit their commercial use.
 
UNPROVEN SAFETY AND EFFECTIVENESS OF POTENTIAL PRODUCTS; UNCERTAINTIES RELATED
TO CLINICAL TRIALS
 
     Before obtaining regulatory approvals for the commercial sale of any of its
products under development, the Company must demonstrate through preclinical
studies and clinical trials that the product is safe and efficacious for use in
each indication. The results from preclinical testing and early clinical trials
may not be predictive of results that will be obtained in large-scale clinical
trials, and there can be no assurance that the Company's clinical trials will
demonstrate the safety and effectiveness of any products or will result in
marketable products. A number of companies have suffered significant setbacks in
advanced clinical trials, even after promising results in earlier trials. The
Company, the FDA or other regulatory authorities may suspend or terminate
clinical trials at any time.
 
     The Company relies on scientific, technical and clinical data supplied by
its academic collaborators and licensors in the evaluation and development of
potential products, including Sn-117m DTPA, which was licensed from BNL. BNL
conducted the Phase I and the Phase II clinical trials of the compound. There
can be no assurance that there are no errors or omissions in such data that
would materially adversely affect the development of such products.
 
     The rate of completion of the Company's clinical trials is dependent upon,
among other things, the rate of patient enrollment. Patient enrollment is a
function of many factors, including the size of the patient population, the
nature of the protocol, the proximity of patients to clinical sites and the
eligibility criteria for the study. Delays in planned patient enrollment may
result in increased costs, program delays, or both, which could have a material
adverse effect on the Company.
 
     The Company relies, in part, on clinical research organizations to conduct
its clinical trials. There can be no assurance that such entities will conduct
the clinical trials successfully.
 
     The Company currently intends to complete Phase III clinical trials of P280
for the diagnosis of DVT and P829 for the diagnosis of neuroendocrine tumors in
the first half of 1997. These are the Company's most advanced product
candidates. There can be no assurance that the Company will meet its development
 
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schedule for P280 or P829, or that P280 or P829 or any of the Company's other
products in development will receive marketing approval in any country on a
timely basis, or at all. If the Company were unable to complete clinical trials
or demonstrate the safety and effectiveness of P280 or P829, the Company's
business, financial condition and results of operations could be materially
adversely affected.
 
     The Company also is currently conducting clinical trials with respect to
certain of its other Techtides and plans to continue clinical trials of its
therapeutic radiopharmaceutical, Sn-117m DTPA. There can be no assurance that
any of these clinical trials will be successfully completed within any specified
time period, if at all. There also can be no assurance that the results from any
of these clinical trials will warrant the commencement of further clinical
trials or that the Company will not encounter problems in these or other
clinical trials which would cause the Company or the FDA to delay or suspend the
trials. In Phase I clinical trials of one of its Techtides, P483H for the
medical imaging of infection due to inflammation, the compound concentrated in
patients' stomachs at unexpectedly high levels. As a result, the Company
conducted additional preclinical testing of this compound and alternative
compounds in animals to determine the cause of this phenomenon and recently
initiated a new Phase I clinical trial of a new formulation of P483H. In a pilot
study of a compound for medical imaging of atherosclerotic plaque, the Company
determined that the compound did not exhibit sufficient sensitivity to warrant
continuing development of the compound. The Company currently is synthesizing
new compounds for this application and screening them in animal models. See
"Business -- Products Under Development" and "Business -- Government
Regulation."
 
NO ASSURANCE OF REGULATORY APPROVAL; EXTENSIVE GOVERNMENT REGULATION
 
     The production and the marketing of the Company's products and the
Company's ongoing research and development activities are and will be subject to
extensive regulation by numerous federal, state and local governmental
authorities in the United States. The Company has had only limited experience in
filing or pursuing applications necessary to gain regulatory approvals.
Preclinical testing of the Company's product development candidates is subject
to Good Laboratory Practice ("GLP") requirements and the manufacture of any
products developed by the Company will be subject to Good Manufacturing Practice
("GMP") requirements prescribed by the FDA.
 
     The regulatory process, which includes preclinical studies, clinical trials
and ongoing post-approval testing of each compound to establish or monitor its
safety and effectiveness, takes many years and requires the expenditure of
substantial resources. The Company has limited experience in filing or pursuing
applications necessary to gain regulatory approval. There can be no assurance
that, even after the performance of clinical studies, and the passage of time
and the expenditure of such resources, regulatory approval will be obtained for
any products developed by the Company. The Company's analysis of data obtained
from preclinical and clinical activities is subject to confirmation and
interpretation by regulatory authorities which could delay, limit or prevent FDA
regulatory approval. The Company or the FDA may suspend clinical trials at any
time if the participants in such trials are being exposed to unanticipated or
unacceptable health risks. Moreover, if regulatory approval to market a product
is granted, such approval may entail limitations on the indicated uses for which
it may be marketed. Failure to comply with applicable regulatory requirements
can, among other things, result in fines, suspension or withdrawal of regulatory
approvals, product recalls, seizure of products, operating restrictions and
criminal prosecutions. FDA policy may change and additional government
regulations may be established that could prevent or delay regulatory approval
of the Company's potential products. In addition, a marketed product, its
manufacturer and its manufacturing facilities are subject to continual review
and periodic inspections, and subsequent discovery of previously unknown
problems with a product, manufacturer or facility may result in restrictions on
such product or manufacturer, including withdrawal of the product from the
market. All of the foregoing regulatory matters also will be applicable to
development, manufacturing and marketing undertaken by any strategic partners of
the Company.
 
     There can be no assurance that additional statutes or regulations
applicable to the Company's business will not be adopted, impose substantial
additional costs or otherwise adversely affect the Company's operations.
 
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     The use, handling, storage and disposal of products containing
radioisotopes, such as Sn-117m and sources of technetium, are regulated by the
Nuclear Regulatory Commission and by state authorities. Enforcement of existing
laws and regulations or future amendments or limitations thereto could have a
material adverse effect on the market for radiopharmaceuticals and on the
Company's business, financial condition and results of operations. See "Business
-- Government Regulation."
 
     The Company is also subject to numerous and varying foreign regulatory
requirements governing the design and conduct of clinical trials and the
manufacturing and marketing of its products. The approval procedure varies among
countries and can involve additional testing, and the time required to obtain
approval may differ from that required to obtain FDA approval. The foreign
regulatory approval process may include all of the risks associated with
obtaining FDA approval set forth above, and there can be no assurance that
foreign regulatory approvals will be obtained on a timely basis, if at all.
Approval by the FDA does not ensure approval by regulatory authorities in other
countries and approval by one foreign regulatory authority does not ensure
approval by regulatory authorities in other foreign countries or by the FDA.
There can be no assurance that the Company or its strategic marketing partners
will file for regulatory approvals or receive necessary approvals to
commercialize its products in any market. Delays in receipt of or failure to
receive regulatory approvals, or the loss of previously received approvals,
would have a material adverse effect on the Company's business, financial
condition and results of operations. See "Business -- Government Regulation."
 
NEED TO ESTABLISH COLLABORATIVE COMMERCIAL RELATIONSHIPS; DEPENDENCE ON PARTNERS
 
     Diatide's business strategy includes entering into strategic alliances or
marketing and distribution arrangements with corporate partners, primarily
pharmaceutical companies, for the development, commercialization and marketing
and distribution of certain of its potential products worldwide. To date, the
Company is a party to a collaborative arrangement with only one corporate
partner, Nycomed. There can be no assurance that the arrangement with Nycomed
will be scientifically or commercially successful. In the event that this
arrangement is terminated, such action might adversely affect the Company's
ability to develop, commercialize, market and distribute certain of its
potential products. If Dr. Richard T. Dean, the Company's President and Chief
Executive Officer, ceases to be employed by Diatide through August 11, 1997,
other than as a result of his death or disability or termination for cause,
Nycomed may terminate its collaboration with the Company. In addition, the
Company does not plan to conduct extensive Phase II/III clinical trials of
Sn-117m DTPA unless it enters into a corporate collaboration for the completion
of the development and the commercialization of Sn-117m DTPA. There can be no
assurance that the Company will be able to negotiate any additional
collaborative or marketing and distribution arrangements, that such arrangements
will be available to the Company on acceptable terms or that any such
relationships, if established, will be scientifically or commercially
successful. The Company's product candidates will only generate milestone
payments and royalties from collaborators upon the occurrence of significant
preclinical and clinical development, requisite regulatory approvals, the
establishment of manufacturing capabilities and successful marketing.
 
     There can be no assurance that the Company's collaborative partners will
not be pursuing alternative technologies or developing alternative products
either on their own or in collaboration with others, including the Company's
competitors, as a means for developing imaging agents or treatments for the
diseases targeted by these collaborative programs. For example, Nycomed
manufactures and distributes a wide variety of imaging agents for other
modalities that may compete against the products that Nycomed licenses from
Diatide or co-markets with Diatide. The Company's business also will be affected
by the success of its corporate partners in marketing any successfully developed
products within the geographic areas in which such partners are granted
marketing rights. A reduction in sales efforts or a discontinuance of sales of
the Company's products by collaborative or corporate partners, who are not
within the control of the Company, may result in reduced revenues and have a
material adverse effect on the Company's business, financial condition and
results of operations. See "Risk Factors -- Attraction and Retention of Key
Management and Qualified Personnel" and "Business -- Products Under
Development," "-- Corporate Collaborations" and "-- Marketing and Distribution."
 
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HISTORY OF OPERATING LOSSES AND ACCUMULATED DEFICIT; UNCERTAINTY OF FUTURE
PROFITABILITY
 
     Diatide has incurred net losses since its inception. At March 31, 1996, the
Company's accumulated deficit was approximately $24.7 million. No revenues have
been generated from product sales, and no product sales revenues are anticipated
for a number of years. The Company expects to incur additional significant
operating losses over the next several years and expects cumulative losses to
increase significantly as the Company's research and development and clinical
trial efforts expand. The Company expects that losses will fluctuate from
quarter to quarter and that such fluctuations may be substantial. The Company's
ability to achieve profitability is dependent in part on obtaining regulatory
approvals for its products, entering into satisfactory agreements with
pharmaceutical corporate partners for research and development and
commercialization of its products and developing the capacity to manufacture,
market and sell its products or entering into satisfactory arrangements for such
manufacture, marketing and sale with third parties. There can be no assurance
that the Company will obtain required regulatory approvals, enter into any
additional agreements for drug discovery, development and commercialization,
develop the capacity to manufacture and sell its products (or enter into
arrangements therefor with third parties) or ever achieve sales or
profitability. See "Management's Discussion and Analysis of Financial Condition
and Results of Operations."
 
FUTURE CAPITAL NEEDS; UNCERTAINTY OF ADDITIONAL FUNDING
 
     The Company's future capital requirements will depend on many factors,
including continued progress in its research and product development programs,
the magnitude of these programs, the results of preclinical studies and clinical
trials, the time and costs involved in obtaining regulatory approvals, the costs
involved in filing, prosecuting, enforcing and defending patent claims,
competing technological and market developments, the ability of the Company to
establish and maintain collaborative academic and commercial research,
development and marketing relationships, and the costs and success of
commercialization activities and arrangements.
 
     Based upon its current operating plan, the Company anticipates that its
existing capital resources, together with the proceeds of this offering and
interest earned thereon, will be adequate to satisfy its capital requirements
for at least the next 24 months. The Company anticipates that it may be required
to raise substantial additional funds, including through collaborative
relationships and public or private financings. No assurance can be given that
additional financing will be available, or, if available, that it will be
available on acceptable terms. If additional funds are raised by issuing equity
securities, further dilution to then existing stockholders will result.
Additionally, the terms of the financing may adversely affect the holdings or
the rights of the then existing stockholders. If adequate funds are not
available, the Company may be required to significantly curtail one or more of
its research or product development programs, or obtain funds through
arrangements with collaborative partners or others that may require the Company
to relinquish rights to certain of its technologies, product candidates or
products which the Company would otherwise pursue on its own. See "Business --
Products Under Development" and "Management's Discussion and Analysis of
Financial Condition and Results of Operations -- Liquidity and Capital
Resources."
 
INTENSE COMPETITION AND RISK OF TECHNOLOGICAL OBSOLESCENCE
 
     There are many companies, both private and publicly traded, that are
conducting extensive research and development activities on technologies and
products similar to or competitive with the Company's technologies and proposed
products. For example, many other companies are actively seeking to develop
nuclear medicine imaging agents that will compete with the Company's Techtides.
There can be no assurance that the Company's competitors will not succeed in
developing technology similar to the Company's proprietary process of
radiolabelling peptides with technetium used in the Company's Techtides.
 
     The pharmaceutical industry is characterized by rapid and substantial
technological change and there can be no assurance that the Company's
competitors will not succeed in developing products which are more effective
than any that are being developed by the Company, or which would render
Diatide's technologies and products obsolete and noncompetitive. For example,
diagnostic imaging tests may be developed that are more cost-effective and have
superior imaging quality than the Company's tests or new radiopharmaceuticals
may
 
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be developed that have superior targeting and binding qualities than the
Company's Techtides. Certain radiopharmaceuticals already have been approved for
sale for the diagnosis or treatment of the indications targeted by the Company's
products under development. In particular, OctreoScan(R), a peptide-based
radiopharmaceutical, is available for the diagnosis of neuroendocrine tumors,
Ceretec(R), a radiopharmaceutical labelled with technetium, is available for
imaging inflammation due to infection, and Metastron(R) is available for the
reduction of pain due to metastatic cancer to the bone. There are several
well-established medical imaging modalities that currently, and will continue
to, compete against nuclear medicine imaging, including x-rays, CT, MRI and
ultrasound, and there are alternative therapeutics available for the treatment
of the cancer indications that are the subject of the Company's therapeutic
programs.
 
     The Company has numerous competitors in the United States and
internationally, which include, among others, pharmaceutical and chemical
companies, biotechnology firms, universities and other research institutions.
Large pharmaceutical companies with significant research, development, marketing
and manufacturing operations in the nuclear medicine field include The DuPont
Merck Pharmaceutical Company ("DuPont Merck"), Mallinckrodt Group Inc.
("Mallinckrodt") and Amersham International PLC ("Amersham"). Many of the
Company's competitors have substantially greater financial, technical and human
resources than the Company. In addition, many of these competitors have
significantly greater experience than the Company in undertaking preclinical
studies and human clinical trials of new pharmaceutical products and obtaining
FDA and other regulatory approvals of products for use in health care.
Accordingly, the Company's competitors may succeed in obtaining FDA or other
regulatory approvals for products more rapidly than the Company. Furthermore, if
the Company is permitted to commence commercial sales of products, it will also
be competing with respect to manufacturing efficiency and marketing
capabilities, areas in which it has limited or no experience. See "Risk Factors
-- Attraction and Retention of Key Management and Qualified Personnel" and
"Business -- Competition" and "-- Marketing and Distribution."
 
UNCERTAINTY REGARDING PATENTS AND PROPRIETARY RIGHTS
 
     The Company's success will depend in part on its ability to develop
patentable products, enforce its patents and obtain patent protection for its
products both in the United States and in other countries. The Company intends
to file applications as appropriate for patents covering both its products and
processes. However, the patent positions of pharmaceutical and biotechnology
firms, including Diatide, are generally uncertain and involve complex legal and
factual questions. No assurance can be given that patents will issue from any
patent applications owned by or licensed to Diatide or that, if patents do
issue, the claims allowed will be sufficiently broad to protect the Company's
technology. In addition, no assurance can be given that any issued patents owned
by or licensed to the Company will not be challenged, invalidated or
circumvented, or that the rights granted thereunder will provide competitive
advantages to the Company.
 
     The commercial success of the Company will also depend in part on its
neither infringing patents issued to competitors or others nor breaching the
technology licenses upon which the Company's products might be based. The
Company's licenses of patents and patent applications impose various
commercialization, sublicensing, royalty and other payment, insurance and other
obligations on the Company. Failure of the Company to comply with these
requirements could result in conversion of the licenses from being exclusive to
nonexclusive in nature or termination of the licenses. The Company is aware of
patents and patent applications belonging to competitors, and it is uncertain
whether these patents and patent applications will require the Company to alter
its products or processes, pay licensing fees or cease certain activities.
Competitors of the Company and other third parties hold issued patents and
pending patent applications which may result in claims of infringement against
the Company or other patent litigation. In particular, the Company is aware of
one European patent issued to a pharmaceutical company which, if valid, may be
infringed by P748. The holder of this patent has indicated to the Company that
it is not prepared to offer a license under the patent to the Company. There can
be no assurance that the Company will be able to successfully obtain a license
to any technology that it may require or that, if obtainable, such technology
can be licensed at a reasonable cost or on an exclusive basis. Failure by the
Company to obtain a license to any technology that it may require to
commercialize its products could have a material adverse effect on the Company.
See "Business -- Patents, Trade Secrets and Licenses."
 
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     The pharmaceutical and biotechnology industries have been characterized by
extensive litigation regarding patents and other intellectual property rights.
Litigation, which could result in substantial cost to the Company, may be
necessary to enforce any patents issued or licensed to the Company and/or to
determine the scope and validity of others' proprietary rights. The Company also
may have to participate in interference proceedings declared by the United
States Patent and Trademark Office, which could result in substantial cost to
the Company, to determine the priority of inventions. Furthermore, the Company
may have to participate at substantial cost in International Trade Commission
proceedings to abate importation of products which would compete unfairly with
products of the Company.
 
     Amendments to Title 35 of the United States Code as amended by the General
Agreement on Tariffs and Trade ("GATT"), implementing the Uruguay Round
Agreement Act of 1994, have affected the period of enforceability of United
States patents. United States patents that issue from applications filed before
June 1, 1995 will be enforceable for the longer of 17 years from the date of
issue or 20 years from the earliest claimed priority date. United States patents
that issue from applications filed on or after June 1, 1995 will be enforceable
for 20 years from the earliest of the filing date or the earliest claimed
priority date. While the Company cannot predict the effect that such laws will
have on its business, the adoption of such laws could effectively reduce the
term during which a marketed product could be protected by patents.
 
     Diatide engages in collaborations, sponsored research agreements and other
agreements with academic researchers and institutions and United States
government agencies. Under the terms of such agreements, third parties may have
rights in certain inventions developed during the course of the performance of
such collaborations and agreements.
 
     The Company relies on trade secrets and proprietary know-how which it seeks
to protect, in part by confidentiality agreements with its employees,
consultants, members of its Scientific Advisory Board, outside scientific
collaborators and sponsored researchers and other advisors. There can be no
assurance that these agreements will not be breached, that the Company would
have adequate remedies for any breach or that the Company's trade secrets will
not otherwise become known or be independently developed by competitors. Failure
to obtain or maintain patent and trade secret protection, for any reason, could
have a material adverse effect on the Company. See "Business -- Patents, Trade
Secrets and Licenses."
 
UNCERTAINTY OF MARKET ACCEPTANCE OF TECHNOLOGY AND PRODUCTS
 
     The commercial success of the Company's products, when and if approved for
marketing by the FDA, will depend upon their acceptance by the medical community
and third party payors as clinically useful, cost-effective and safe. The
synthetic peptide-based radiopharmaceutical technology being developed by the
Company is relatively new. To date, the Company is aware of only one imaging
product and no therapeutic products based on this scientific approach that has
been approved for sale by the FDA. Peptide-based radiopharmaceuticals have not
been extensively tested in humans. Market acceptance and thus, sales of the
Company's products, will depend on several factors, including the receipt of
regulatory approval in the United States, Europe, the Far East and elsewhere,
safety, price, ease of administration and effectiveness and extensive physician
education. There can be no assurance that the Company's products will gain
market acceptance. Failure to achieve market acceptance would have a material
adverse effect on the Company's business, financial condition and results of
operations. See "Business -- Government Regulation."
 
ABSENCE OF SALES AND MARKETING EXPERIENCE
 
     Although Diatide plans to rely significantly on collaborative partners for
the marketing and distribution of its products through co-marketing or other
licensing or distribution arrangements, the Company expects to market and sell
certain of its products directly and to engage in certain other marketing
activities in collaboration with its collaborative partners. The Company has no
experience in sales, marketing or distribution. The Company does not expect to
establish a direct sales capability until such time as one or more of its
products in development approaches marketing approval. The Company has not
developed a specific sales and marketing plan with respect to any of its
potential products. Although Diatide plans to have only a
 
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small, specialized in house sales group, it will need to recruit and train
appropriate personnel and develop a supporting distribution capability.
 
     To the extent the Company enters into marketing or distribution
arrangements with collaborative partners, any revenues the Company receives will
depend upon the efforts of third parties. There can be no assurance that any
third party will market the Company's products successfully or that any
third-party collaboration will be on terms favorable to the Company. If any
marketing partner does not market a product successfully, the Company's business
would be materially adversely affected. If Diatide's plan to rely on corporate
partners for significant aspects of marketing and selling the Company's products
is unsuccessful for any reason, Diatide may need to recruit and train a far
larger marketing and sales force than it currently anticipates doing, which
would entail the incurrence of significant additional costs.
 
     There can be no assurance that the Company would be able to attract and
build a sufficient marketing staff or sales force, that the cost of establishing
such a marketing staff or sales force will be justifiable in light of any
product revenues or that the Company's direct sales and marketing efforts will
be successful. In addition, if the Company succeeds in bringing one or more
products to market, it may compete with other companies that currently have
extensive and well-funded marketing and sales operations. There can be no
assurance that the Company's marketing and sales efforts would enable it to
compete successfully against such other companies. See "Business -- Marketing
and Distribution" and "-- Corporate Collaborations."
 
LIMITED MANUFACTURING CAPABILITY; DEPENDENCE ON SOLE SOURCE SUPPLIER
 
     The Company lacks commercial-scale facilities to manufacture its products
in accordance with current GMP requirements prescribed by the FDA. To date, the
Company has relied on a large third party pharmaceutical company for the
manufacture of its peptides for clinical trials and has entered into an
arrangement with a GMP-qualified third party manufacturer for the supply of
Sn-117m for clinical trials. The Company expects to be dependent on third party
manufacturers or collaborative partners for all of its commercial production of
peptides. There are a limited number of manufacturers that operate under GMP
regulations capable of manufacturing the Company's products. In the event that
the Company is unable to obtain contract manufacturing, or obtain such
manufacturing on commercially reasonable terms, it may not be able to
commercialize its products as planned. Where third-party arrangements are
established, the Company will depend upon such third parties to perform their
obligations in a timely manner. There can be no assurance that third parties
depended upon by the Company will perform and any failures by third parties may
delay clinical trial development or the submission of products for regulatory
approval, impair the Company's ability to commercialize its products as planned
and deliver products on a timely basis, or otherwise impair the Company's
competitive position, which could have a material adverse effect on the
Company's business, financial condition or results of operations.
 
     The Company purchases its synthetic peptides from a sole source supplier
and may enter into similar arrangements with respect to other components of its
products. While the Company is aware of alternative sources for its peptides,
the establishment of additional or replacement suppliers could be time consuming
and result in a supply interruption and significant additional regulatory delays
and expense. The establishment of an alternative source of supply or any
significant supply interruption could have a materially adverse effect on the
Company's ability to develop and manufacture its potential products and,
therefore, upon its business, financial condition and results of operations. See
"Business -- Manufacturing."
 
     If the Company determines to develop its own manufacturing capabilities, it
will need to recruit qualified personnel and build or lease the requisite
facilities and equipment because it has no experience in manufacturing on a
commercial scale and no facilities or equipment therefor. There can be no
assurance that Diatide will be able to successfully develop its own
manufacturing capabilities or as to the cost thereof or the time required. In
addition, the manufacture of any products by the Company is subject to
regulation by the FDA and comparable agencies in foreign countries. Delay in
complying or failure to comply with such manufacturing requirements could
materially adversely affect the marketing of the Company's products and the
Company's business, financial condition and results of operations.
 
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HAZARDOUS MATERIALS
 
     The Company's research and development involves the controlled use of
hazardous materials, chemicals and various radioactive compounds. Although the
Company believes that its safety procedures for handling, storing and disposing
of such materials and the safety procedures of the third parties who ship such
materials for the Company comply with the standards prescribed by federal, state
and local regulations, the risk of accidental contamination or injury from these
materials cannot be completely eliminated. In the event of such an accident, the
Company could be held liable for significant damages and any such liability
could have a material adverse effect on the Company's business, financial
condition and results of operations. See "Business -- Government Regulation."
 
POTENTIAL PRODUCT LIABILITY EXPOSURE AND INSURANCE
 
     The use of any of the Company's potential products in clinical trials and
the commercial sale of any products may expose the Company to potential product
liability risks which are inherent in the testing, manufacturing, marketing and
sale of human diagnostic and therapeutic products. Product liability claims
might be made directly by consumers, health care providers or by pharmaceutical
companies or others selling such products. There can be no assurance that
product liability claims, if made, would not result in a recall of the Company's
products or a change in the indications for which they may be used. Diatide has
limited product liability insurance coverage, and such coverage is subject to
various deductibles. Such coverage is expensive, and no assurance can be given
that the Company will be able to maintain or obtain such insurance at reasonable
cost or in sufficient amounts to protect the Company against losses due to
liability claims that could have a material adverse effect on the Company. See
"Risk Factors -- Unproven Safety and Effectiveness of Potential Products;
Uncertainties Related to Clinical Trials."
 
UNCERTAINTY OF HEALTH CARE REFORM MEASURES
 
     Federal, state and local officials and legislators (and certain foreign
government officials and legislators) have proposed or are reportedly
considering proposing a variety of reforms to the health care systems in the
United States and abroad. The Company cannot predict what health care reform
legislation, if any, will be enacted in the United States or elsewhere.
Significant changes in the health care system in the United States or elsewhere
are likely to have a substantial impact over time on the manner in which the
Company conducts its business. Such changes could have a material adverse effect
on the Company. The existence of pending health care reform proposals could have
a material adverse effect on the Company's ability to raise capital. Further, to
the extent that proposals have a material adverse effect on other pharmaceutical
companies that are prospective corporate partners for the Company, the Company's
ability to establish collaborative commercial relationships may be adversely
affected. Furthermore, the Company's ability to commercialize its potential
products may be adversely affected to the extent that such proposals have a
material adverse effect on the business, financial condition and profitability
of other companies that are prospective corporate partners with respect to
certain of the Company's proposed products. See "Business -- Government
Regulation."
 
UNCERTAINTY OF PHARMACEUTICAL PRICING AND ADEQUATE REIMBURSEMENT
 
     The Company's ability to commercialize its products successfully will
depend in part on the extent to which appropriate reimbursement levels for the
cost of such products and related treatment are obtained from government
authorities, private health insurers and other organizations, such as health
maintenance organizations ("HMOs"). Third-party payors are increasingly
challenging the prices charged for medical products and services. Also the trend
towards managed health care in the United States and the concurrent growth of
organizations such as HMOs, which could control or significantly influence the
purchase of health care services and products, as well as legislative proposals
to reduce government insurance programs, may all result in lower prices for the
Company's products. The cost containment measures that health care providers are
instituting could affect the Company's ability to sell its products and may have
a material adverse effect on the Company.
 
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<PAGE>   9
 
     There can be no assurance that reimbursement in the United States or
foreign countries will be available for any of the Company's products, or if
available, will not be decreased in the future, or that reimbursement amounts
will not reduce the demand for, or the price of, the Company's products. The
unavailability or inadequacy of third-party reimbursement for the Company's
products would have a material adverse effect on the Company.
 
ATTRACTION AND RETENTION OF KEY MANAGEMENT AND QUALIFIED PERSONNEL
 
     The Company is highly dependent on the principal members of its management
and scientific staff, particularly Dr. Dean, the Company's President and Chief
Executive Officer, the loss of whose services could have a material adverse
effect on the Company. The Company is a party to an employment agreement with
Dr. Dean that extends through April 2, 1998, subject to automatic extension for
additional one-year periods unless either Dr. Dean or the Company provides
written notice to the contrary to the other party at least six months prior to
the expiration period. In the event Dr. Dean ceases to be employed by Diatide
through August 11, 1997, other than as a result of his death or disability or
termination for cause, Nycomed may terminate its collaboration with the Company,
which would result in a material loss of research and development revenues to
the Company and might adversely affect the Company's ability to develop,
commercialize, market and distribute certain of its potential products. Also,
recruiting and retaining qualified scientific personnel to perform research and
development work in the future will be critical to the Company's success. There
can be no assurance that the Company will be able to attract and retain such
highly skilled personnel on acceptable terms given the competition for
experienced scientists among numerous pharmaceutical, biotechnology and health
care companies, universities and non-profit research institutions. See "Risk
Factors -- Need to Establish Collaborative Commercial Relationships; Dependence
on Partners." The Company does not carry key-man insurance with respect to any
of its executive officers.
 
     The Company's anticipated growth and expansion into areas and activities
requiring additional expertise, such as clinical trials, governmental approvals,
production and marketing, are expected to require the addition of new management
personnel and the development of additional expertise by existing management
personnel. The failure to acquire such services or to develop such expertise
could have a material adverse effect on the Company.
 
CLAIM BY MALLINCKRODT
 
     On May 16, 1996, the Company received a letter from Mallinckrodt Group Inc.
("Mallinckrodt") in which Mallinckrodt stated, among other things, that "there
appears to have been a systematic effort by Diatide to gain access to
proprietary knowledge and processes developed by Mallinckrodt." Mallinckrodt
noted that four former managers at Mallinckrodt are currently employed by
Diatide and asserted that it had grounds to bring a cause of action against
Diatide for tortious interference with the employment agreements that it had
with its former managers. Diatide believes that Mallinckrodt's claims are
without merit. Although there can be no assurance that Mallinckrodt will not
commence a legal action in furtherance of its claims or that any such claims
will not be upheld, Diatide intends to vigorously contest and defend any such
action.
 
NO PUBLIC MARKET; POSSIBLE VOLATILITY OF SHARE PRICE; DILUTION
 
     Prior to this offering, there has been no public market for the Common
Stock of the Company, and there can be no assurance that an active trading
market will develop or be sustained after this offering. The initial public
offering price was determined by negotiations among the Company and the
representatives of the Underwriters based upon several factors and may not be
indicative of future market prices. See "Underwriting" for a discussion of the
factors considered in determining the initial public offering price. The market
price of the Company's Common Stock could be subject to wide fluctuations in
response to quarterly variations in the Company's operating results,
announcements of technological innovations or new commercial diagnostic or
therapeutic products by the Company, its collaborative partners or its
competitors, governmental regulation, developments in patent or other
proprietary rights and public concern regarding the safety, effectiveness or
other implications of the products being developed by the Company. In addition,
the stock market has experienced extreme price and volume fluctuations. This
volatility has significantly affected the market prices
 
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of securities of many pharmaceutical companies for reasons frequently unrelated
to or disproportionate to the operating performance of the specific companies.
These broad market fluctuations may adversely affect the market price of the
Company's Common Stock.
 
     Purchasers of shares of Common Stock in this offering will experience an
immediate and substantial dilution of $6.23 per share in the net tangible book
value of the Common Stock from the initial public offering price (based on the
initial public offering price of $8.50 per share). Additional dilution is likely
to occur upon exercise of outstanding warrants and stock options. See
"Dilution."
 
CONTROL BY DIRECTORS AND OFFICERS
 
     Upon completion of this offering, the Company's directors, executive
officers and principal stockholders, and their affiliates, will beneficially own
approximately 60.1% of the Company's outstanding Common Stock (approximately
58.3% if the underwriters exercise their over-allotment option in full). As a
result, these stockholders, if acting together, will have the ability to control
the outcome of corporate actions requiring stockholder approval, including
actions concerning the election of directors and the approval of certain mergers
and other significant corporate transactions, including a sale of substantially
all of the Company's assets, irrespective of how other stockholders of the
Company may vote. This concentration of ownership may have the effect of
delaying or preventing a change in control of the Company. See "Management" and
"Principal Stockholders."
 
SHARES ELIGIBLE FOR FUTURE SALE; REGISTRATION RIGHTS
 
     A substantial number of outstanding shares of Common Stock and shares of
Common Stock issuable upon exercise of outstanding options and warrants will
become eligible for future sale in the public market at prescribed times. Sales
of substantial numbers of shares of Common Stock in the public market following
this offering could adversely affect prevailing market prices. The Securities
and Exchange Commission (the "SEC") has proposed an amendment to Rule 144 under
the Securities Act of 1933, as amended (the "Securities Act"), that, if adopted,
would permit certain shares to be sold one year earlier than otherwise provided
by the current version of Rule 144. Holders of 7,976,644 shares of Common Stock
(including 125,330 shares of Common Stock that may be acquired upon the exercise
of warrants) are entitled to certain rights with respect to registration of such
shares of Common Stock for offer or sale to the public. Any such sales may have
an adverse effect on the Company's ability to raise needed capital and may
adversely affect the market price of the Common Stock. See "Shares Eligible for
Future Sale," "Description of Capital Stock," and "Underwriting."
 
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ANTI-TAKEOVER PROVISIONS
 
     The Company's Certificate of Incorporation (the "Certificate of
Incorporation"), as in effect upon the closing of this offering, will require
that any action required or permitted to be taken by stockholders of the Company
must be effected at a duly called annual or special meeting of stockholders and
may not be effected by any consent in writing, and will require reasonable
advance notice by a stockholder of a proposal or director nomination which such
stockholder desires to present at any annual or special meeting of stockholders.
Special meetings of stockholders may be called only by the President of the
Company or by the Board of Directors. The Certificate of Incorporation provides
for a classified Board of Directors, and members of the Board of Directors may
be removed only for cause upon the affirmative vote of holders of at least
two-thirds of the shares of capital stock of the Company entitled to vote. In
addition, the Board of Directors will have the authority, without further action
by the stockholders, to fix the rights and preferences of, and issue shares of,
Preferred Stock. These provisions, other provisions of the Certificate of
Incorporation, and provisions in certain of the Company's stock options which
provide for acceleration of exercisability upon a change in control of the
Company and the fact that, upon the completion of this offering, the Company's
directors, executive officers and principal stockholders, and their affiliates,
will beneficially own approximately 60.1% of the Company's outstanding Common
Stock (approximately 58.3% if the underwriters exercise their over-allotment
option in full), may have the effect of deterring hostile takeovers or delaying
or preventing changes in control or management of the Company, including
transactions in which stockholders might otherwise receive a premium for their
shares over then current market prices. In addition, these provisions may limit
the ability of stockholders to approve transactions that they may deem to be in
their best interests. See "Description of Capital Stock -- Preferred Stock" and
"-- Delaware Law and Certain Charter and By-Law Provisions."
 
NO DIVIDENDS ANTICIPATED IN FUTURE
 
     The Company has not paid any dividends on the Common Stock since its
inception and does not anticipate paying any dividends in the future.
Declaration of dividends on the Common Stock will depend upon, among other
things, future earnings, if any, the operating and financial condition of the
Company, its capital requirements and general business conditions. See "Dividend
Policy."
 
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