<PAGE>   1
                                                                    EXHIBIT 4.3

                                ESCROW AGREEMENT

         This Escrow Agreement (the "Agreement") is made and entered into as of
March __, 2000, by and among W.R. Hambrecht & Company, LLC., a Delaware limited
liability company (the "Placement Agent"), SunTrust Bank, a Georgia banking
corporation (the "Escrow Agent") and MD2patient, Inc. (the "Corporation").

         WHEREAS, the Placement Agent is acting as a placement agent for the
Corporation in connection with its sale of up to 34,000,000 shares of Series B
Convertible Preferred Stock of the Corporation (the "Series B Shares") and
2,000,000 shares of Series A Convertible Preferred Stock of the Corporation
(the "Series A Shares") at a price of $1.00 per Share, pursuant to the terms
and conditions set forth in the Corporation's Registration Statement on Form
S-1, as amended (Reg. No. 333-91619) (the "Registration Statement"); and

         WHEREAS, in order to facilitate the closing of the purchase of the
Shares, until such time as the minimum of 5,000,000 of the Series B Shares (the
"Minimum Shares") shall have been sold as provided in the Registration
Statement, the Placement Agent desires that the Escrow Agent receive, hold and
distribute payments received by the Placement Agent from investors for the
purchase of Series B Shares and Series A Shares (the "Minimum Escrowed Assets")
in accordance with the terms hereof; and

         WHEREAS, in order to facilitate the closing of the purchase of the
Series B Shares and Series A Shares remaining after the sale of the Minimum
Shares (the "Remaining Shares"), the Placement Agent desires that the Escrow
Agent receive, hold and distribute payments received by the Placement Agent
from investors for the remaining Series B Shares and Series A Shares (the
"Remaining Escrowed Assets") in accordance with the terms hereof.

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants hereinafter set forth, the parties agree as follows:

                                   ARTICLE 1
                 ESCROW OF PROCEEDS RELATING TO MINIMUM SHARES

         1.    Minimum Shares Escrow Deposit. Until the Minimum Shares shall
have been sold, the Placement Agent will deliver, by 12:00 p.m. PST of the next
business day, all payments for the Series B Shares and Series A Shares received
by the Placement Agent from investors for the purchase of Series B Shares and
Series A Shares as set forth in the Registration Statement, to the Escrow Agent,
by wire transfer of immediately available funds. All such payments so deposited
with the Escrow Agent shall remain the property of the investor until their
distribution pursuant to Section 3 hereof and not subject to any liens or
charges by the Corporation, or the Escrow Agent, or judgments or creditor's
claims against the Corporation until released to the Corporation as hereinafter
provided.

         2.    Investment of Minimum Shares Escrow Deposit. The Escrow Agent
shall invest the Minimum Escrowed Assets in a U.S. Treasury Securities Money
Market Fund or such other short-term market investments available to the Escrow
Agent that the Corporation may


<PAGE>   2

designate. If the Corporation shall not have designated an investment for the
Minimum Escrowed Assets, the Escrow Agent may invest the Minimum Escrowed
Assets in a money market sweep account being used by the Escrow Agent. The
Escrow Agent shall not be liable for losses on any investments made by it in
good faith.

         3.    Distribution of Proceeds Relating to Minimum Shares. The Escrow
Agent shall distribute the Minimum Escrowed Assets held by it under this
Agreement as follows:

               (a)  Upon receipt of a certificate titled Minimum Shares
               Certificate signed by an authorized representative of the
               Corporation and an authorized representative of the Placement
               Agent, to the effect that the Minimum Shares have been sold and
               the Placement Agent has received funds therefor, the Escrow
               Agent shall deliver to the Corporation by wire transfer of
               immediately available funds or other form of payment mutually
               acceptable to the Corporation and the Escrow Agent an amount
               equal to the difference between (i) the Minimum Escrowed Assets
               and any interest thereon then held by the Escrow Agent under
               this Agreement, minus (ii) $400,000. The Escrow Agent shall
               deliver to the Placement Agent by wire transfer of immediately
               available funds $400,000.

               (b)  Upon receipt of a certificate titled Escrow Return
               Certificate signed by an authorized representative of the
               Corporation and an authorized representative of the Placement
               Agent, setting forth the name and address of each investor, the
               taxpayer identification number of each investor, the number of
               Series B Shares and/or Series A Shares purchased, and the amount
               paid therefor and directing the Escrow Agent to return the funds
               delivered to it under this Agreement to the investors in the
               offering, or in the event the Escrow Agent shall have received
               no certificate from an authorized representative and an
               authorized representative of the Placement Agent pursuant to
               either subsection (a) above or this subsection (b) on or prior
               to 5:00 p.m. on January 2, 2001 (the "Termination Date"), the
               Escrow Agent shall deliver to each investor the amount paid by
               such investor for Series B Shares and/or Series A Shares and any
               interest thereon then held by the Escrow Agent under this
               Agreement.

                                   ARTICLE II
                ESCROW OF PROCEEDS RELATING TO REMAINING SHARES

         4.    Remaining Shares Escrow Deposit. Until all of the Remaining
Shares shall have been sold, the Placement Agent will deliver, by 12:00 p.m.
PST of the next business day, all payments for the Series B Shares and Series A
Shares received by the Placement Agent from investors for the purchase of
Series B Shares and Series A Shares as set forth in the Registration Statement,
to the Escrow Agent, by wire transfer of immediately available funds. All such
payments so deposited with the Escrow Agent shall remain the property of the
investor until their distribution pursuant to Section 6 hereof and not subject
to any liens or charges by the Corporation, or the Escrow Agent, or judgments
or creditor's claims against the Corporation until released to the Corporation
as hereinafter provided. The Placement Agent will provide the Escrow Agent with
a written account of each sale, which account shall set forth, among other


                                       2
<PAGE>   3

things, the investor's name and address, the investor's taxpayer identification
number, the number of Series B Shares and/or Series A Shares purchased, and the
amount paid therefor.

         5.    Investment of Remaining Shares Escrow Deposits. The Escrow Agent
shall invest the Remaining Escrowed Assets in a U.S. Treasury Securities Money
Market Fund or such other short-term market investments available to the Escrow
Agent that the Corporation may designate. If the Corporation shall not have
designated an investment for the Remaining Escrowed Assets, the Escrow Agent
may invest the Remaining Escrowed Assets in a money market sweep account being
used by the Escrow Agent. The Escrow Agent shall not be liable for losses on
any investments made by it in good faith.

         6.    Distribution of Proceeds Relating to Remaining Shares. From time
to time, the Escrow Agent shall distribute the Remaining Escrowed Assets held
by it under this Agreement as follows:

               (a)  Upon receipt of a certificate titled Remaining Shares
               Certificate signed by an authorized representative of the
               Corporation and an authorized representative of the Placement
               Agent, to the effect that the Corporation desires to close on a
               specific amount of proceeds from the sale of Remaining Shares
               and the Placement Agent has received funds for such Remaining
               Shares, the Escrow Agent shall deliver to the Corporation by
               wire transfer of immediately available funds or other form of
               payment mutually acceptable to the Corporation and the Escrow
               Agent an amount equal to:

                    (i)  the Remaining Escrowed Assets requested by the
                         Corporation and the Placement Agent to be delivered to
                         the Corporation and any interest thereon then held by
                         the Escrow Agent under this Agreement, minus

                    (ii) (A) for the first of 1,250,000 shares of the Remaining
                         Shares sold by the Corporation, an amount equal to
                         eight (8%) of the Remaining Escrowed Assets requested
                         by the Corporation and the Placement Agent to be
                         delivered to the Corporation (the "Adjusted Fee"),

                         (B) for the next 10,416,666 of the Remaining Shares
                         sold by the Corporation, zero dollars ($0), and

                         (C) for all of the remaining Remaining Shares sold by
                         the Corporation, an amount equal to three (3%) of the
                         Remaining Escrowed Assets requested by the Corporation
                         and the Placement Agent to be delivered to the
                         Corporation (the "3% Fee").

               For each such distribution, the Escrow Agent shall deliver the
               Adjusted Fee or 3% fee, as the case may be, to the Placement
               Agent by wire transfer of immediately available funds.


                                       3
<PAGE>   4

               (b)  If on the Termination Date the Corporation shall have sold
               any of the Remaining Shares, the Escrow Agent shall deliver to
               the Corporation by wire transfer of immediately available funds
               or other form of payment mutually acceptable to the Corporation
               and the Escrow Agent an amount equal to the difference between
               (i) any and all Remaining Escrowed Assets and any interest
               thereon then held by the Escrow Agent under this Agreement,
               minus (ii) three percent (3%) of the aggregate amount of such
               Remaining Escrowed Assets. For such distribution, the Escrow
               Agent shall deliver to the Placement Agent by wire transfer of
               immediately available funds three percent (3%) of the aggregate
               amount of such Remaining Escrowed Assets.

                                  ARTICLE III
                                 MISCELLANEOUS

         7.    Professional Services Used by Escrow Agent. The Escrow Agent may
engage the services of such attorneys, accountants, and other professionals as
the Escrow Agent may, in its reasonable discretion, deem advisable to carry out
its duties under the Agreement. The Corporation agrees to reimburse the Escrow
Agent for all reasonable costs, expenses and professional fees incurred
hereunder.

         8.    Limit on Escrow Agent's Responsibility. The Escrow Agent shall
have no duties or obligations hereunder except as expressly set forth herein,
shall be responsible only for the performance of such duties and obligations,
shall not be required to take any action otherwise than in accordance with the
terms hereof and shall not be in any manner liable or responsible for any loss
or damage arising by reason of any act or omission to act by it hereunder or in
connection with any of the transactions contemplated hereby, including, but not
limited to, any loss that may occur by reason of forgery, false
representations, the exercise of its discretion, or any other reason, except
for its gross negligence or willful misconduct.

         9.    Indemnification by the Corporation. The Corporation agrees to
indemnify, defend and hold harmless the Escrow Agent from any and all liability
of any kind whatsoever arising by virtue of its services as Escrow Agent
hereunder, except for liabilities due to the Escrow Agent's gross negligence or
willful misconduct.

         10.   Reliance on Opinion of Counsel. The Escrow Agent hereunder shall
be entitled to rely upon the advice of its counsel in any action taken in its
capacity as Escrow Agent hereunder and shall be protected from any liability of
any kind for actions taken in reasonable reliance upon such opinion of its
counsel.

         11.   Resignation. The Escrow Agent may resign at any time upon ten
(10) days' written notice to the Corporation and the Placement Agent. Such
resignation shall take effect upon receipt by the Escrow Agent of an instrument
of acceptance executed by a successor escrow agent and subscribed and consented
to by the Corporation and the Investors, and the delivery by the Escrow Agent
to such successor of any funds held under this Agreement. The Escrow Agent, if
it has not received such an instrument of acceptance prior to the expiration of
ten (10) business


                                       4
<PAGE>   5

days after the giving of notice of resignation, shall be discharged of its
duties and obligations hereunder only upon the deposit of any funds being held
by it under this Agreement into, and the acceptance thereof by, the Chancery
Court of Davidson County, Tennessee, to which application shall be made for the
appointment of a successor escrow agent. Any successor escrow agent so
appointed shall succeed to all of the rights, duties and responsibilities of
the Escrow Agent.

         12.   Escrow Agent's Fees. The Corporation agrees to pay the Escrow
Agent's usual and customary fees (as set forth on Appendix A attached hereto)
for performing its obligations under the Agreement. However, no such fees or
reimbursements for cost or expenses, indemnification for any damages incurred
by the Escrow Agent, or any monies whatsoever shall be paid out of or
chargeable to any of the funds escrowed under this Agreement.

         13.   Securities Administrator. Each of the parties hereto hereby
agrees that it will provide any state securities administrator relating to the
Registration Statement and the offering the right to inspect and make copies of
the records of the Escrow Agent relating to this Agreement at any reasonable
time wherever such records are located.

         14.   Notice. All notices, certificates and other communications
hereunder shall be in writing and shall be sufficiently given and shall be
deemed given when delivered, postage prepaid, addressed as follows by certified
mail:

         To the Escrow Agent:

         SunTrust Bank
         424 Church Street
         6th Floor
         Nashville, Tennessee  37219
         Attn:  Donna Williams
         Phone:  (615) 748-4745
         Fax:  (615) 748-5331

         To the Placement Agent:

         W.R. Hambrecht & Co., LLC
         550 Fifteenth Street
         San Francisco, California  94103
         Attn:  Chris Nordquiest
                Jessica Porten
         (415) 551-8600

         To the Corporation:

         MD2patient, Inc.
         501 Corporate Centre Drive, Suite 200
         Franklin, Tennessee  37067
         Attn:  James G. Petway, Jr.
         (615) 383-8400


                                       5
<PAGE>   6

         Any party may, by notice given hereunder, designate any future or
different address to which subsequent notices, certificates and other
communications shall be sent.

         15.   Binding Effect. This Agreement shall inure to the benefit of and
shall be binding upon the parties hereto and their respective heirs, executors,
successors, administrators and assigns.

         16.   Severability. In the event any provision of this Agreement shall
be held invalid or unenforceable by any court of competent jurisdiction, such
holding shall not invalidate or render unenforceable any other provision
hereof.

         17.   Execution of Counterparts. This Agreement may be executed in
several counter-parts, each of which shall be an original, and all of which
shall constitute one and the same instrument.

         18.   Applicable Law. This Agreement shall be construed and governed
exclusively by the laws of the State of Tennessee, without regard to its
principles of conflicts of law.

         19.   Headings. The headings used in this Agreement have been prepared
for the convenience of reference only and shall not control, affect the
meaning, or be taken as an interpretation of any provision of this Agreement.

         20.   Amendments. This Agreement shall not be amended except upon the
written consent of all parties hereto.




                    [remainder of page intentionally blank]



                                       6
<PAGE>   7


         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date first above written.


                                 SUNTRUST BANK


                                 By:
                                    --------------------------------------

                                 Title:
                                       -----------------------------------



                                 W.R. HAMBRECHT & CO, LLC


                                 By:
                                    --------------------------------------

                                 Title:
                                       -----------------------------------



                                 MD2PATIENT, INC.


                                 By:
                                    --------------------------------------

                                 Title:
                                       -----------------------------------


                                       7
<PAGE>   8

                                   APPENDIX A


                                MD2patient, Inc.
                         SunTrust Bank, as Escrow Agent
                         Subscription Escrow Agent Fees


Escrow Fee:                                                  $__________

Transaction Fee:                                             $__________
(Deposits/Disbursements)


Out-of-Pocket expenses such as, but not limited to, postage, courier,
insurance, long distance telephone calls, facsimile, stationery, travel, legal
and/or accounting, etc., will be billed at cost.

These fees do not cover extraordinary services which will be priced according
to time and scope of duties.

It is acknowledged that the schedule of fees shown above are acceptable for the
services agreed upon and the undersigned authorizes SunTrust Bank to perform
these services.