Rev1

NEITHER THIS AGREEMENT NOR THE SECURITIES WHICH ARE TO BE EXCHANGED HEREUNDER
HAVE BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933 (THE
"ACT").  ACCORDINGLY, NO TRANSFER OF SUCH SECURITIES OR ANY INTEREST THEREIN
IN THE MARKETS OF THE UNITED STATES MAY BE MADE EXCEPT PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT UNLESS THE ISSUER OF THE
SECURITIES HAS RECEIVED AN OPINION OF COUNSEL SATISFACTORY TO IT THAT SUCH
TRANSFER DOES NOT REQUIRE REGISTRATION UNDER THE ACT.


                        SHARE  EXCHANGE  AGREEMENT


  THIS SHARE EXCHANGE AGREEMENT (the "Agreement"), made on the 1st day of
March, 1996 and effective as of March 29, 1996, is by and among:

  PHARMA PATCH PLC, a public limited company of the Republic of Ireland
  (herein called "PHARMA PATCH") with its principal office at 15-16
  FitzWilliam Place, Dublin 2, Ireland; 

  THERAPEUTIC PATCH RESEARCH N.V., a body corporate organized under the
  laws of The Netherlands Antilles (herein called "TPR"), with its
  principal office at De Ruyterkade 62, P.O. Box 812, Willemstad, Curacao,
  The Netherlands Antilles and its mailing address at Statenhof Building,
  Reaal 5-V,  P.O. Box 4, 2350 AA Leiderdorp, The Netherlands;

  SALIVA RESEARCH LIMITED, a body corporate organized under the laws of
  Gibraltar (herein called "SRL"), with its principal office at 4 Irish
  Place, P.P. Box 240, Gibraltar, Europe and its mailing address at
  Statenhof Building, Reaal 5-V,  P.O. Box 4, 2350 AA Leiderdorp, The
  Netherlands; and

  WESTCLIFF PARTNERS INC., a body corporate organized under the laws of
  the Republic of Panama (herein called "WPI"), with its principal office
  and mailing address at Statenhof Building, Reaal 5-V,  P.O. Box 4, 2350
  AA Leiderdorp, The Netherlands.


                                 RECITALS:

  WHEREAS, TPR, SRL and WPI each own of record and beneficially 300,000
shares of the common capital stock in VISTA TECHNOLOGIES INC., a body
corporate of the State of Nevada, United States (herein called "VISTA"), for
an aggregate of 900,000 shares of VISTA common stock (the "Vista SHARES");

  WHEREAS, effective as of March 1, 1996, PHARMA PATCH desires to acquire
from TPR, SRL and WPI all of the Vista SHARES solely in exchange for 4,500,000
newly issued American Depositary Receipts ("Pharma Patch ADRs") each Pharma
Patch ADR representing one Ordinary Share, IR Pound .01 par value, in PHARMA
PATCH, all upon the terms and conditions set forth in this Exchange Agreement.

  NOW, THEREFORE, in consideration of the premises, the parties hereto
mutually covenant, promise and agree as follows:


Exchange Agreement                                                   -1-
<PAGE>

1.      EXCHANGE OF VISTA SHARES FOR PHARMA PATCH ADRS

  1.1.  CLOSING.   The closing for the consummation of the transactions
contemplated by this Agreement ("Closing") shall occur on March 29, 1996 (the
"Closing Date") and shall take place at the offices of Multibreen, B.V., at
Statenhof Building, Reaal 5-V, 2350 AA Leiderdorp, The Netherlands, unless
another time and place is mutually agreed to by the parties.  Upon the
Closing, all the conditions set forth in this Agreement shall have been
satisfied except to the extent any such conditions shall have been expressly
waived in writing by all of the parties hereto.

  1.2.  DELIVERY OF VISTA SHARES.   On the Closing Date, each of TPR, SRL
and WPI shall deliver to PHARMA PATCH certificates evidencing 300,000 of the
Vista SHARES (for a total of 900,000 Vista SHARES), each duly endorsed in
favor of PHARMA PATCH with medallion signature guarantee and accompanied by a
certificate in the form attached hereto confirming the authority of the
officer, managing director or other agent executing the aforesaid endorsement.

  1.3.  DELIVERY OF PHARMA PATCH ADRS.  On the Closing Date, PHARMA PATCH
shall deliver to each of TPR, SRL and WPI certificates evidencing 1,500,000 of
the Pharma Patch ADRs (for a total of 4,500,000 Pharma Patch ADRs), each duly
registered in the names of TPR, SRL and WPI, respectively.

2.      U.S. SECURITIES LAWS.    All of the parties hereto acknowledge that the
common stock of VISTA and the American Depositary Receipts evidencing ordinary
shares of PHARMA PATCH are traded in the United States securities markets. 
Neither the Vista SHARES nor the Pharma Patch ADRs to be exchanged hereunder
have been registered under the U.S. Securities Act of 1933, as amended (the
"Securities Act").  Each party acknowledges that the exchange of securities
hereunder is among investors who are not U.S. persons as defined in Rule
902(o) of Regulation S ("Regulation S") promulgated under the Securities Act
in reliance upon the transactional exemption afforded by Regulation S in
connection with a private placement offshore offer, sale and exchange relating
to securities of VISTA and PHARMA PATCH.  Each party acknowledges it is
familiar with and understands the terms of Regulation S, and has had the
opportunity to consult with its legal counsel concerning this Agreement and
Regulation S.  Accordingly, each party acknowledges that the subsequent
transfer of all securities covered by this Agreement within the United States
markets or otherwise within the jurisdiction of the United States is
restricted by the Securities Act as well as state laws within the United
States.

3.      REPRESENTATIONS, WARRANTIES AND AGREEMENTS OF TPR, SRL AND WPI.  Each of
TPR, SRL and WPI represents and warrants to PHARMA PATCH that:

  3.1.  such party is a body corporate duly organized, validly existing
and in good standing under the laws of the jurisdiction of its incorporation
indicated in the preamble to this Agreement, with all requisite power and
authority to own its property and assets, to carry on its business as it is
now being conducted and to enter into and execute this Agreement and perform
its obligations hereunder. 

  3.2.  at the Closing Date, all of the Vista SHARES to be transferred,
assigned and delivered by such party to PHARMA PATCH hereunder will be owned
beneficially and of record by such party, shall be validly issued, fully paid
and nonassessable securities of VISTA, and such party owns, possesses and has
good and marketable title to transfer such Vista SHARES to PHARMA PATCH at
Closing hereunder free and clear of all liens, charges, demands, security
interests or other adverse claims whatsoever or howsoever arising.



Exchange Agreement                                                   -2-
<PAGE>

  3.3.  such party is not a "U.S. Person" as that term is defined in Rule
902(o) of Regulation S; such party was not formed specifically for the purpose
of investing in Regulation S securities or formed specifically for the purpose
of investing in this Agreement or the securities of PHARMA PATCH; such party
is not registered as an issuer under the Securities Act and is not required to
be registered with the U.S. Securities and Exchange Commission under the
Investment Company Act of 1940; such party has no reason to believe that any
offer to enter into this Agreement has been made by PHARMA PATCH to such party
in the United States; at the times of the original offer relating to, and
execution of, this Agreement, such party was located and resident outside the
United States; and such party is entering into this Agreement and acquiring
Pharma Patch ADRs hereunder for its own account for investment, and not on
behalf of any U.S. Person as defined in Rule 902(o) of Regulation S or with a
view to the distribution of such securities.

  3.4.  neither such party, nor any of its affiliates nor any person
acting on its behalf or any behalf of any such affiliate, has engaged, or will
engage, in any activity undertaken for the purpose of, or that could
reasonable be expected to have the effect of, conditioning the markets in the
United States for any of the securities of PHARMA PATCH or VISTA, including
but not limited to effecting any sale or short sale or the acquisition of any
put option relating to the securities of PHARMA PATCH for the account of such
party or any of its affiliates prior to the expiration of any restricted
period contained in Regulation S or engaging in any course of conduct that
would have the effect of influencing the public market price of such
securities (any such activity, or any other course of conduct defined as a
Directed Selling Effort in Rule 902 of Regulation S, being herein called a
"Directed Selling Effort");  such party and its representatives have not
conducted any Directed Selling Effort and will not engage in any such Directed
Selling Effort within the United States through the expiration of any
restricted period set forth in Rule 903 of Regulation S.

  3.5.  such party agrees that all offers and sales of any securities of
PHARMA PATCH or VISTA for the account of such party or for the account of any
of its affiliates as of the date hereof and through the expiration of the any
restricted period set forth in Rule 903 of Regulation S shall not be made to
U.S. Persons or for the account or benefit of U.S. Persons and shall otherwise
be made in compliance with the provisions of Regulation S and any other
applicable provisions of the United States securities laws.

  3.6.  such party acknowledges and agrees that following the expiration
of any restricted period provided by Rule 903 of Regulation S, any interest in
this Agreement or in the Pharma Patch ADRs may be resold within the
jurisdiction of the United States or to U.S. Persons [as defined in Rule
902(o) of Regulation S] by or for the account of the parties hereto only  (i)
pursuant to a registration statement under the Securities Act, or  (ii)
pursuant to an exemption from such registration and only following the
expiration of any restricted period required by Regulation S.

  3.7.  such party acknowledges that if any subsequent transfer of the
Pharma Patch ADRs is to be made in reliance upon an exemption under the
Securities Act, the issuer of the securities being so transferred may require
an opinion of counsel satisfactory to the issuer that such transfer may be
made pursuant to an applicable exemption under the Securities Act;  such party
further acknowledges that, so long as appropriate, a legend similar to the
following may appear on the certificates representing the Pharma Patch ADRs: 
"These securities have not been registered under the Securities Act of 1933
and may be reoffered and sold only if registered or if an exemption from such
registration is available in the opinion of counsel satisfactory to the
issuer."

  3.8.  such party has sufficient knowledge and experience in financial
and business matters so that it is able to evaluate the merits and risks of
this Agreement and an investment in restricted securities


Exchange Agreement                                                   -3-
<PAGE>

of PHARMA PATCH;  such party has had substantial experience in previous
private and public purchases of speculative and restricted securities,
understands that an investment in PHARMA PATCH securities is speculative, and
can afford to sustain a complete loss of its investment.

  3.9.  such party acknowledges that it has had an opportunity to ask
questions of and to receive answers from one or more of the executive officers
of PHARMA PATCH as such party deems necessary in order for it to make an
informed decision with respect to this Agreement and its agreement to acquire
restricted securities of PHARMA PATCH and has received complete and
satisfactory answers to all such inquiries.

  3.10. this Agreement has been duly authorized, executed and delivered by
such party and is a valid and binding agreement enforceable in accordance with
its terms, subject only to bankruptcy, insolvency, fraudulent transfer,
reorganization, moratorium and similar laws of general application to or
affecting creditors' rights generally and to general principles of equity; 
such party has full power and authority necessary to enter into this Agreement
and to perform its obligations hereunder.

  3.11. the execution and delivery of this Agreement, and the consummation
of the transactions contemplated herein, do not and will not conflict with or
result in a breach by such party of any of the terms or provisions of, or
constitute a default under, its charter documents, its memorandum or articles
of association or incorporation, its by-laws, any action of its directors or
shareholders, or any indenture, mortgage, deed of trust or other agreement or
instrument by which such party or any of its properties or assets are bound,
or any existing applicable law, rule or regulation or any applicable decree,
judgment or order of any court, regulatory body, administrative agency or
other governmental body having jurisdiction over such party or any of its
properties or assets.

4.      REPRESENTATIONS, WARRANTIES AND AGREEMENTS OF PHARMA PATCH.  PHARMA
PATCH represents and warrants to each of TPR, SRL and WPI that:

  4.1.  PHARMA PATCH is a body corporate duly organized, validly existing
and in good standing as a public limited company under the laws of the
Republic of Ireland, with all requisite power and authority to own its
property and assets, to carry on its business as it is now being conducted and
to enter into and execute this Agreement and perform its obligations
hereunder. 

  4.2.  PHARMA PATCH is not an investment company registered or required
to register as such under the United States Investment Company Act of 1940.

  4.3.  The American Depositary Receipts evidencing ordinary shares of
PHARMA PATCH is a class of securities registered under Section 12(g) of the
U.S. Securities Exchange Act of 1934 ("Exchange Act"), and PHARMA PATCH has
filed all reports and documents required to be filed pursuant to the Exchange
Act for a period of at least twelve months preceding the date hereof (or for
such shorter period as PHARMA PATCH was required to file such materials).

  4.4.  The Pharma Patch ADRs and the underlying ordinary shares of PHARMA
PATCH represented thereby, when issued and delivered at Closing by  PHARMA
PATCH hereunder, will be duly and validly authorized and issued, fully paid
and nonassessable securities of  PHARMA PATCH and will not subject the holders
thereof to personal liability by reason of being such holders.   

  4.5.  PHARMA PATCH is acquiring the Vista SHARES hereunder for its own
account for investment, and not with a view to the distribution of such
securities.


Exchange Agreement                                                   -4-
<PAGE>

  4.6.  Neither PHARMA PATCH, nor any of its affiliates nor any person
acting on its behalf or any behalf of any such affiliate, has engaged, or will
engage, in any activity undertaken for the purpose of, or that could
reasonable be expected to have the effect of, conditioning the markets in the
United States for any of the securities of PHARMA PATCH or VISTA, including
but not limited to effecting any sale or short sale or the acquisition of any
put option relating to the securities of VISTA for the account of PHARMA PATCH
or any of its affiliates prior to the expiration of any restricted period
contained in Regulation S or engaging in any course of conduct that would have
the effect of influencing the public market price of such securities (any such
activity, or any other course of conduct defined as a Directed Selling Effort
in Rule 902 of Regulation S, being herein called a "Directed Selling Effort"); 
PHARMA PATCH and its representatives have not conducted any Directed Selling
Effort and will not engage in any such Directed Selling Effort within the
United States through the expiration of any restricted period set forth in
Rule 903 of Regulation S.

  4.7.  PHARMA PATCH acknowledges and agrees that any interest in this
Agreement or in the Vista SHARES may be resold within the markets or the
jurisdiction of the United States only  (i) pursuant to a registration
statement under the Securities Act, or  (ii) pursuant to an exemption from
such registration.

  4.8.   PHARMA PATCH acknowledges that if any subsequent transfer of the
Vista SHARES is to be made in reliance upon an exemption under the Securities
Act, the issuer of the securities being so transferred may require an opinion
of counsel satisfactory to the issuer that such transfer may be made pursuant
to an applicable exemption under the Securities Act;  PHARMA PATCH further
acknowledges that, so long as appropriate, a legend similar to the following
may appear on the certificates representing the Vista SHARES:  "These
securities have not been registered under the Securities Act of 1933 and may
be reoffered and sold only if registered or if an exemption from such
registration is available in the opinion of counsel satisfactory to the
issuer."

  4.9.  PHARMA PATCH has sufficient knowledge and experience in financial
and business matters so that it is able to evaluate the merits and risks of
this Agreement and an investment in restricted securities of VISTA;  PHARMA
PATCH and its executive officers have had substantial experience in previous
private and public purchases of speculative and restricted securities, and
understands that an investment in VISTA securities is speculative and subject
to risk of loss.

  4.10. PHARMA PATCH acknowledges that it has had an opportunity to ask
questions of and to receive answers from one or more of the executive officers
of VISTA as PHARMA PATCH deems necessary in order for it to make an informed
decision with respect to this Agreement and its agreement to acquire
restricted securities of VISTA and has received complete and satisfactory
answers to all such inquiries.

  4.11. This Agreement has been duly authorized, executed and delivered by
PHARMA PATCH and is a valid and binding agreement enforceable in accordance
with its terms, subject only to bankruptcy, insolvency, fraudulent transfer,
reorganization, moratorium and similar laws of general application to or
affecting creditors' rights generally and to general principles of equity; 
PHARMA PATCH has full power and authority necessary to enter into this
Agreement and to perform its obligations hereunder.

  4.12. The execution and delivery of this Agreement, and the consummation
of the transactions contemplated herein, do not and will not conflict with or
result in a breach by PHARMA PATCH of any of the terms or provisions of, or
constitute a default under, its charter documents, its memorandum or articles
of association or incorporation, its by-laws, any action of its directors or
shareholders, or any indenture, mortgage, deed of trust or other agreement or
instrument by which PHARMA PATCH or any


Exchange Agreement                                                   -5-
<PAGE>
of its properties or assets are bound, or any existing applicable law, rule or
regulation or any applicable decree, judgment or order of any court,
regulatory body, administrative agency or other governmental body having
jurisdiction over such party or any of its properties or assets.

5.      OTHER CONDITIONS TO CLOSING.    At the Closing:

  5.1.  REPRESENTATIONS AND WARRANTIES.  The representations and
warranties of all parties set forth in this Agreement shall be true and
correct in all material respects as of the Closing Date as though made on and
as of the Closing Date.

  5.2.  COMPLIANCE WITH AGREEMENT.  All parties hereto shall have
performed in all material respects all obligations required to be performed by
them under this Agreement at or prior to the Closing Date.

  5.3.  NO INJUNCTION.  None of the parties hereto shall be subject to any
injunction or preliminary restraining order against the consummation of the
transactions contemplated by this Agreement.

  5.4.  ABSENCE OF ANY ADVERSE CHARGES.   There shall have been no
material adverse change in the business, financial condition or prospects of
VISTA or PHARMA PATCH between the date of this Agreement and the Closing Date.

  5.5.  LEGAL MATTERS.  The form and substance of all legal matters con-
templated hereby and of all instruments and documents delivered hereunder
shall be reasonably acceptable to counsel for each of the parties.
 
  5.6.  AUTHORIZING RESOLUTIONS.   Each of the parties hereto shall have
delivered to each of the other parties a copy of resolutions, certified by the
secretary or an assistant secretary of such corporate party, adopted by its
board of directors necessary to evidence its authorization of the execution
and delivery by such party of this Agreement and the transactions contemplated
herein.

6.      OTHER PROVISIONS.

  6.1.  NO GOVERNMENTAL APPROVAL.   Each of the parties understand that no
governmental agency of any jurisdiction has passed upon or made any
recommendation or endorsement of the transactions contemplated by this
Agreement or an investment in any of the securities covered by this Agreement.

  6.2.  TRANSACTION EXPENSES.   Each of the undersigned agrees to pay its
own expenses incident to the performance of its obligations hereunder.

  6.3.  GOVERNING LAW.   Each of the undersigned agree that except to the
extent U.S. securities laws may be applicable as a matter of public policy,
this Agreement shall be governed by and construed in accordance with the laws
of The Netherlands, and without regard to principles of conflicts of law.

  6.4.  TIME.  Time shall be of the essence of this Agreement.

  6.5.  ENTIRE AGREEMENT.   This Agreement contains the entire agreement
among the parties with respect to the transactions contemplated hereby, and
supersedes all prior arrangements or understandings, written or oral, among
the parties with respect thereto.  This Agreement may be amended or modified
only by a writing executed by the party or parties to be bound by such
amendment or modification.



Exchange Agreement                                                   -6-
<PAGE>

  6.6.  SUCCESSORS AND ASSIGNS.   All representations, warranties,
covenants and agreements of the parties shall bind their respective successors
and assignees and shall inure to the benefit of their respective successors
and permitted assignees.

  6.7.  INTERPRETATION.  This Agreement shall be interpreted according to
its fair meaning and not for or against either party who may have drafted
provisions hereof.

  6.8   CAPTIONS.  The headings and captions appearing in this Agreement
are inserted for convenience of reference only and shall not constitute a part
thereof and shall not be used in construction or interpretation.

  6.9.  COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original but all of which
together shall constitute one in the same instrument.

  IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed as of the day and year first above written.


SIGNED, SEALED AND DELIVERED    )     PHARMA PATCH PLC.
    in the presence of          )
                          )
                          )     Per: ___________________________
____________________________    )           Murray B. Watson
         Witness                )           Title:  Chairman and Chief
                          )                   Executive Officer
                          )
                          )
SIGNED, SEALED AND DELIVERED    )     THERAPEUTIC PATCH RESEARCH N.V.
    in the presence of          )
                          )
                          )     Per: ___________________________
____________________________    )           Dick van der Vennen
         Witness                )           Title:  Managing Director
                          )
                          )
SIGNED, SEALED AND DELIVERED    )     SALIVA RESEARCH LIMITED
    in the presence of          )
                          )
                          )     Per: ____________________________
____________________________    )           Jac. J. Lam
         Witness                )           Title:  Managing Director
                          )
                          )
SIGNED, SEALED AND DELIVERED    )     WESTCLIFF PARTNERS INC.
    in the presence of          )
                          )
                          )     Per: ____________________________
____________________________    )           Jac. J. Lam
         Witness                )           Title:  President and Managing
                                              Director


Exchange Agreement                                                   -7-