<PAGE>
                                                                    EXHIBIT 10.1



                         SECURITIES PURCHASE AGREEMENT

        This Securities Purchase Agreement (the "Agreement") is made as of June
7, 2002 by and between ____ ("Purchaser") and NeoTherapeutics, Inc. ("Company")
whereby the parties agree as follows:

        The Purchaser shall buy from the Company and the Company agrees to sell
to the Purchaser: (i) ___ shares (the "Shares") of the Company's common stock,
par value $.001 per share (the "Common Stock"), at a price of $0.2325 per share
for an aggregate purchase price of $____ (the "Purchase Price"), and (ii) a
five-year warrant to purchase up to ____ shares of Common Stock (the "Warrant"),
at an exercise price of $0.275 per share, in the form attached hereto as Exhibit
A.

        The Shares and the Warrant are being issued and sold pursuant to a
registration statement on Form S-3, File No. 333-53108, which registration
statement has been declared effective by the Securities and Exchange Commission.
The Company is delivering herewith a prospectus supplement on Form 424(b)(5)
regarding the issuance and sale of the Shares and the Warrant prior to funding,
a copy of which is attached hereto as Exhibit B. The Shares and Warrant are free
of restrictive legends and the Shares and the shares of Common Stock issuable
upon exercise of the Warrant, when issued upon exercise of the Warrant in
accordance with its terms and as described in the prospectus supplement, will be
free of any resale restrictions.

        Prior to the close of business on June 7, 2002:

        1.     The Purchaser shall wire the Purchase Price to the Company to the
               account set forth below.

               Company Wire Transfer Instructions:


               ------------------------------

              ------------------------------

               ------------------------------

               ------------------------------

               ------------------------------

               ------------------------------

        2.     The Company shall (A) deliver a facsimile copy of the Warrant to
               the Purchaser at the address for notices set forth below, with
               the original Warrant to be delivered to such address on the next
               following business day, and (B) cause its transfer agent to
               transmit the Shares electronically to the Purchaser by crediting
               the account set forth below through the Deposit Withdrawal Agent
               Commission system.

<PAGE>

               Purchaser DWAC Instructions:

               DTC No.:
                           ---------------
               Account No.:
                           ---------------
               Reference:
                           ---------------
               Notices to the Company shall be delivered to:

               NeoTherapeutics, Inc.
               Attention: Samuel Gulko
               Senior Vice President Finance,
               Chief Financial Officer, Secretary and Treasurer
               157 Technology Drive,
               Irvine, California  92618
               Facsimile:  (949) 788-6706

               Notices to Purchaser shall be delivered to:

               Purchaser Name:
                              ---------------
               Attn:
                              ---------------
               Address:
                              ---------------
               Facsimile:
                              ---------------

Delivery of an executed copy of a signature page to this Agreement by facsimile
transmission shall be effective as delivery of a manually executed copy of this
Agreement and shall be effective and enforceable as the original. This Agreement
may be executed in one or more counterparts, each of which shall be deemed an
original, but all of which together shall constitute one and the same
instrument. This Agreement shall be governed and construed in accordance with
the internal laws of the State of California without giving effect to the
conflicts of law principles thereunder.



                                       2
<PAGE>

        AGREED AND ACCEPTED, as of the date indicated above:


                                        NeoTherapeutics, Inc.


                                        By:    Samuel Gulko
                                               ---------------------------------

                                        Name:  Samuel Gulko
                                               ---------------------------------

                                        Title: Senior V.P. Finance & Chief
                                               ---------------------------------
                                               Financial Officer
                                               ---------------------------------


                                        Purchaser Name:


                                        ----------------------------------------

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

                                        Name:
                                               ---------------------------------

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



                                       3

<PAGE>

                                    EXHIBIT A


<PAGE>

                                    EXHIBIT B

<PAGE>

                                   SCHEDULE 1


<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
Purchaser                         Shares       Purchase Price         Warrant
--------------------------------------------------------------------------------
<S>                               <C>          <C>                    <C>
Stonestreet Limited Partnership   1,935,483    $450,000               193,548
--------------------------------------------------------------------------------
BNC Bach International, Ltd.      4,000,000    $930,000               400,000
--------------------------------------------------------------------------------
</TABLE>