<PAGE>

                                                                    EXHIBIT 4.8


THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS AND NEITHER THE SECURITIES
NOR ANY INTEREST THEREIN MAY BE OFFERED, SOLD, TRANSFERRED, PLEDGED OR OTHERWISE
DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH
ACT OR SUCH LAWS, WHICH, IN THE OPINION OF COUNSEL FOR THE HOLDER, WHICH COUNSEL
AND OPINION ARE REASONABLY SATISFACTORY TO COUNSEL FOR THIS CORPORATION, IS
AVAILABLE.



                                                                   June 17, 1996



               WARRANT TO PURCHASE SHARES OF SERIES I CONVERTIBLE
                PREFERRED STOCK OF AMERICAN PSYCH SYSTEMS, INC.


      This certifies that _________ (the "Holder"), or its registered
assigns, for value received is entitled, subject to the adjustment and to the
other terms set forth below, to purchase from AMERICAN PSYCH SYSTEMS, INC., a
Delaware corporation (the "Company"), ______ fully paid and nonassessable
shares of the Company's $.001 par value Series I Convertible Preferred Stock
(the "Stock") at a price of $1.22 per share (the "Stock Purchase Price") at
any time on or after June 17, 1996 (the "Commencement Date") but not later
than 5:00 p.m., New York City time, on the Expiration Date (as defined
below). The Stock Purchase Price and, in some cases, the number of shares
purchasable hereunder are subject to adjustment as provided in Section 3 of
this Warrant. This Warrant and all rights hereunder, to the extent not
exercised in the manner set forth herein shall terminate and become null and
void on the Expiration Date. "Expiration' Date" means June 17, 2001.

      This Warrant is subject to the following terms and conditions:

      1.    EXERCISE; ISSUANCE OF CERTIFICATES; PAYMENT FOR SHARES; CONVERSION
            RIGHT.

            1.1   DURATION OF EXERCISE OF WARRANT. This Warrant is exercisable
at the option of the Holder at any time or from time to time but not earlier
than on the Commencement Date or later than 5:00 p.m., New York City time, on
the Expiation Date for all or a portion of the shares of Stock which may be
purchased hereunder.

            1.2   EXERCISE OF WARRANT. Exercise of the Warrant shall be made by
surrender to the Company at its principal office, One Democracy Plaza, 6701
Democracy Boulevard, Suite 555, Bethesda, Maryland 20817 Attention: President
(or at such other location as the Company may advise the Holder in writing) of
this Warrant properly endorsed with the Subscription Agreement attached hereto
as Exhibit A duly filled in and signed and, unless the Conversion Right set
forth in Section 13 is exercised, upon payment in cash or cashier's check of the
aggregate Stock Purchase Price for the number of shares for which this Warrant
is being

<PAGE>

exercised determined in accordance with the provisions hereof. The Company
agrees that the shares of stock purchased under this Warrant shall be and are
deemed to be issued to the Holder as the record owner of such shares as of the
close of business on the date on which this Warrant shall have been surrendered
and payment made for such shares. Subject to the provisions of Section 2,
certificates for the shares of Stock so purchased, together with any other
securities or property to which the Holder is entitled upon such exercise, shall
be delivered to the Holder by the Company's transfer agent at the Company's
expense within a reasonable time after the rights represented by this Warrant
have been exercised. Each stock certificate so delivered shall be in such
denominations of Stock as may be requested by the Holder and shall be registered
in the name of the Holder or such other name as shall be designated by the
holder, subject to the limitations contained in Section 2. If, upon exercise of
this Warrant, fewer than all of the shares of Stock evidenced by this Warrant
are purchased prior to the Expiration Date of this Warrant, a new warrant
substantially in the form of, and on the terms in, this Warrant will be issued
for the remaining number of shares of Stock not purchased upon exercise of this
Warrant.

            1.3   CONVERSION RIGHT. In lieu of the payment of the Stock Purchase
Price, the Holder shall have the right (but not the obligation), to require the
Company to convert this Warrant, in whole or in part, into shares of Stock (the
`Conversion Right") as provided for in this Section 1.3. Upon exercise of the
Conversion Right, the Company shall deliver to the Holder (without payment by
the Holder of any of the Stock Purchase Price) that number of shares of Stock
equal to the quotient obtained by dividing (x) the value of the Warrant at the
time the Conversion Right is exercised (determined by subtracting the aggregate
Stock Purchase Price in effect immediately prior to the exercise of the
Conversion Right from the aggregate Fair Market Value (as hereinafter defined)
for the shares of Stock issuable upon exercise of the Warrant immediately prior
to the exercise of the Conversion Right) by (y) the Fair Market Value of one
share of Stock immediately prior to the exercise of the Conversion Right, as
determined by the Board of Directors in its good faith judgment.

            1.4   EXERCISE OF CONVERSION RIGHT. The conversion rights provided
under Section 1.3 hereof may be exercised in whole or in part and at any time
and from time to time while any Warrants remain outstanding. In order to
exercise the conversion privilege, the Holder shall surrender to the Company, at
its offices, this Warrant accompanied by a duly completed Notice of Conversion
in the form attached hereto as Exhibit B. The presentation and surrender shall
be deemed a waiver of the Holder's obligation to pay all or any portion of the
aggregate purchase price payable for the shares of Stock issuable upon exercise
of this Warrant. This Warrant (or so much thereof as shall have been surrendered
for conversion) shall be deemed to have been converted immediately prior to the
close of business on the day of surrender of such Warrant for conversion in
accordance with the foregoing provisions. As promptly as practicable on or after
the conversion date, the Company shall issue and shall deliver to the Holder (i)
a certificate or certificates representing the largest number of whole shares of
Stock to which the Holder shall be entitled as a result of the conversion, and
(ii) if the Warrant is being converted in part only, a new warrant in principal
amount equal to the unconverted portion of this Warrant. If this Warrant is
executed in whole, in lieu of any fractional shares of Stock to which the Holder
shall be entitled, the Company shall pay to the Holder cash in accordance with
the provisions of Section 12 hereof. For purposes of determining whether to
exercise the conversion rights provided under Section 1.3, the Holder may from
time to time request that the Board of Directors of the Company determine in its
good faith judgment the Fair Market Value of the Stock at such


                                       2
<PAGE>

time, which Fair Market Value would be utilized for purposes of calculating the
number of shares of Stock issuable in connection with a conversion contemplated
to be made by the Holder or any other holder of Warrants; PROVIDED that such
conversion right is exercised within ten business days of the Holders being
notified by the Company of such determination of Fair Market Value. In no event
shall any determination of Fair Market Value in accordance with the preceding
sentence obligate any Holder to exercise the Warrant or any conversion right.
The Company shall promptly advise the Holder and all other holders of Warrants
of any determination by the Board of Directors of Fair Market Value. The Company
shall not be obligated to determine such Fair Market Value on more than two
occasions in any calendar year where no exercise or conversion of Warrants
occurs on the basis of such determined value.

      2.    SHARES TO BE FULLY PAID; RESERVATION OF SHARES. The Company
covenants and agrees that all shares of Stock which may be issued upon the
exercise of this Warrant (the "Warrant Shares") and all shares of Stock issuable
upon conversion of the Warrants (the "Conversion Shares") will, upon issuance,
be duly authorized, validly issued, fully paid and nonassessable and free from
all preemptive rights of any stockholder and free of all taxes, liens and
charges with respect to the issue thereof. The Company covenants that it will
reserve and keep available a sufficient number of shares of its authorized but
unissued Stock for such exercise and/or conversion, as the case may be. The
Company will take all such reasonable action as may be necessary to assure that
such shares of Stock may be issued as provided herein without violation of any
applicable law or regulation, or of any requirements of any domestic securities
exchange or automated quotation system upon which the Stock may be listed.

      3.    ADJUSTMENT OF STOCK PURCHASE PRICE AND NUMBER OF SHARES. The Stock
Purchase Price and, in some cases, the number of shares purchasable upon the
exercise of this Warrant shall be subject to adjustment from time to time upon
the occurrence of certain events described in this Section 3.

            3.1 SUBDIVISION OR COMBINATION OF STOCK AND STOCK DIVIDEND. In case
the Company shall at any time subdivide its outstanding shares of Stock into a
greater number of shares or declare a dividend upon its Stock payable solely in
shares of Stock, the Stock Purchase Price in effect immediately prior to such
subdivision or declaration shall be proportionately reduced and the number of
shares issuable upon exercise of the Warrant shall be proportionately increased.
Conversely, in case the outstanding shares of Stock of the Company shall be
combined into a smaller number of shares, the Stock Purchase Price in effect
immediately prior to such combination shall be proportionately increased, and
the number of shares issuable upon exercise of the Warrant shall be
proportionately reduced.

            3.2 NOTICE OF ADJUSTMENT. Promptly after adjustment of the Stock
Purchase Price or any increase or decrease in the number of shares purchasable
upon the exercise of this Warrant, the Company shall give written notice thereof
by first class mail, postage prepaid, addressed to the registered holder of this
Warrant at the address of such holder as shown on the books of the Company. The
notice shall be signed by the Company's chief financial officer and shall state
the effective date of the adjustment and the Stock Purchase Price resulting from
such adjustment and the increase or decrease, if any, in the number of shares
purchasable at such price upon the exercise of this Warrant, setting forth in
reasonable detail the method of calculation and the facts upon which such
calculation is based.


                                       3
<PAGE>

            3.3   OTHER NOTICES.  If at anytime:

            (a)   the Company shall declare any cash dividend upon its Stock;

            (b)   the Company shall declare any dividend upon its Stock payable
      in stock (other than a dividend payable solely in shares of Stock) or make
      any special dividend or other distribution to the holders of its Stock;

            (c)   there shall be any capital reorganization, or reclassification
      of the Stock of the Company or consolidation or merger of the Company with
      another corporation, or a sale of all or substantially all of the
      Company's assets to another corporation; or

            (d)   there shall be a voluntary or involuntary dissolution,
      liquidation or winding-up of the Company;

then, in any one or more of said cases, the Company shall give, by first class
mail (certified or registered mail in the case of any event referred to in
paragraphs (c) or (4) above, postage prepaid, addressed to the registered holder
of this Warrant at the address of such holder as shown on the books of the
Company, (i) at least 15 days' prior written notice of the date on which the
books of the Company shall close or a record shall be taken for such dividend,
distribution or subscription rights or for determining rights to vote in respect
of any such reorganization, reclassification, consolidation, merger, sale,
dissolution, liquidation or winding-up; and (ii) in the case of any such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or winding-up, at least 20 days' written notice of the date when the
same shall take place. Any notice given in accordance with clause (i) above
shall also specify, in the case of any such dividend, distribution or
subscription rights, the date on which the holders of Stock shall be entitled
thereto. Any notice given in accordance with clause (ii) above shall also
specify the date on which the holders of Stock shall be entitled to exchange
their Stock for securities or other property deliverable upon such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or windingup, as the case may be. If the Holder of the Warrant does
not exercise this Warrant prior to the occurrence of an event described above,
except as provided in Sections 3.1 and 3.4, the Holder shall not be entitled to
receive the benefits accruing to existing holders of the Stock in such event.

            3.4   CHANGES IN STOCK. In case at any time following the date
hereof, the Company shall be a party to any transaction (including, without
limitation, a merger, consolidation, sale of all or substantially all of the
Company's assets or recapitalization of the Stock) in which the previously
outstanding Stock shall be changed into or exchanged for different securities of
the Company or common stock or other securities of another corporation or
interests in a noncorporate entity or other property (including cash) or any
combination of any of the foregoing (each such transaction being herein called
the "Transaction" and the date of consummation of the Transaction being herein
called the "Consummation Date"), then, as a condition of the consummation of the
Transaction, lawful and adequate provisions shall be made so that each Holder,
upon the exercise hereof at any time on or after the Consummation Date, shall be
entitled to receive; and this Warrant shall thereafter represent the right to
receive, in lieu of the Stock issuable upon such exercise prior to the
Consummation Date, the highest amount of securities or other property to which
such Holder would actually have been entitled as a


                                       4
<PAGE>

stockholder upon the consummation of the Transaction if such Holder had
exercised such Warrant immediately prior thereto. The provisions of this Section
3.4 shall similarly apply to successive Transactions.

      4.    ISSUE TAX. The issuance of certificates for shares of Stock upon the
exercise of the Warrant shall be made without charge to the holder of the
Warrant for any issue tax in respect thereof, provided, however, that the
Company shall not be required to pay any tax which may be payable in respect of
any transfer involved in the issuance and delivery of any certificate in a name
other than that of the then holder of the Warrant being exercised.

      5.    NO VOTING OR DIVIDEND RIGHTS; LIMITATION OF LIABILITY. Nothing
contained in this Warrant shall be construed as conferring upon the holder
hereof the right to vote or to consent or to receive notice as a stockholder in
respect of meetings of stockholders for the election of directors of the Company
or any other matters or any rights whatsoever as a stockholder of the Company.
Except for the adjustment to the Stock Purchase Price pursuant to Section 3.1 in
the event of a dividend on the Stock payable in shares of Stock; no dividends or
interest shall be payable or accrued in respect of this Warrant or the interest
represented hereby or the shares purchasable hereunder until, and only to the
extent that, this Warrant shall have been exercised. No provisions hereof, in
the absence of affirmative action by the holder to purchase shares of Stock, and
no mere enumeration herein of the rights or privileges of the holder hereof,
shall give rise to any liability of such holder for the Stock Purchase Price or
as a stockholder of the Company whether such liability is asserted by the
Company or by its creditors.

      6.    RESTRICTIONS ON TRANSFERABILITY OF SECURITIES COMPLIANCE WITH
            SECURITIES ACT.

            6.1 RESTRICTIONS ON TRANSFERABILITY. This Warrant, the Warrant
Shares and the Conversion Shares (collectively, the "Securities"), shall not be
transferable in the absence of Registration under the Act (as defined below) or
an exemption therefrom under said Act.

            6.2 RESTRICTIVE LEGEND. Each certificate representing the Securities
or any other securities issued in respect of the Securities upon any stock
split, stock dividend, recapitalization, merger, consolidation or similar event,
shall be stamped or otherwise imprinted with a legend substantially in the
following form (in addition to any legend required under applicable state
securities laws):

            THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER TEE
            SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS AND
            NEITHER THE SECURITIES NOR ANY INTEREST THEREIN MAY BE OFFERED,
            SOLD, TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT
            TO AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT OR SUCH LAWS
            OR AN EXEMPTION FROM REGISTRATION UNDER SAID ACT OR SUCH LAWS,
            WHICH, IN THE OPINION OF COUNSEL FOR THE HOLDER, WHICH COUNSEL AND
            OPINION ARE REASONABLY SATISFACTORY TO COUNSEL FOR THIS CORPORATION,
            IS AVAILABLE.


                                       5
<PAGE>

            7.    REGISTRATION RIGHTS. The shares of Common Stock issuable upon
conversion of the Warrant Shares and the Conversion Shares (the "Underlying
Common Shares") are entitled to certain registration rights pursuant to the
Amended and Restated Registration Rights Agreement, dated June 17, 1996 (as
amended, supplemented or modified from time to time), among the Company and the
Investors (as defined therein).

            8.    RIGHTS OF FIRST REFUSAL AND CO-SALE. The Warrant Shares, the
Conversion Shares and the Underlying Common Shares are entitled to certain
rights of co-sale and first refusal pursuant to the Amended and Restated Co-Sale
and Restricted Stock Agreement, dated June 17, 1996 (as amended, supplemented or
modified from time to time), among the Company and the Investors (as defined
therein).

            9.    MODIFICATION AND WAIVER.  This Warrant and any provision
hereof may be changed, waived, discharged or terminated only by an instrument
in writing signed by the party against which enforcement of the same is
sought.

            10.   NOTICES. Any notice, request or other document required or
permitted to be given or delivered to the holder hereof or the Company shall,
except as otherwise provided in this Warrant, be delivered or shall be sent by
certified or registered mail, postage prepaid, to each such holder at its
address as shown on the books of the Company.

            11.   APPLICABLE LAW.  This Warrant shall be construed and
enforced in accordance with, and the rights and obligations of the parties
shall be governed by, the laws of the State of Delaware.

            12.   DESCRIPTIVE HEADINGS.  The descriptive headings of several
sections and paragraphs of this Warrant are inserted for convenience only and
do not constitute a part of this Warrant.

            13.   LOST WARRANTS OR STOCK CERTIFICATES. The Company represents
and warrants to the Holder that upon receipt of evidence reasonably satisfactory
to the Company of the loss, theft, destruction or mutilation of any Warrant or
stock certificate and, in the case of any such loss, theft or destruction, upon
receipt of an indemnity and, if requested, bond reasonably satisfactory to the
Company, or in the case of any such mutilation, upon surrender and cancellation
of such Warrant or stock certificate, the Company at its expense will make and
deliver a new Warrant or stock certificate, of like tenor, in lieu of the lost,
stolen, destroyed or mutilated Warrant or stock certificate.

            14.   FRACTIONAL SHARES. No fractional shares shall be issued upon
exercise of this Warrant. The Company shall, in lieu of issuing any fractional
share pay the holder entitled to such fraction a sum in cash equal to the Fair
Market Value of any such fractional interest as it shall appear on the public
market, or if there is no public market for such shares, then as shall be
reasonably determined by the Company.



                                       6
<PAGE>

            IN WITNESS WHEREOF, the Company has caused this Warrant to be
executed by its officer, thereunto duly authorized as of this 17th day of June,
1996.



                                          AMERICAN PSYCH SYSTEMS, INC.


                                          By:_________________________________
                                             Kenneth Kessler, M.D.
                                             President




                                       7