<PAGE>   1
                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM 8-K


                                 CURRENT REPORT


                       PURSUANT TO SECTION 13 OR 15(d) OF
                       THE SECURITIES EXCHANGE ACT OF 1934


         Date of Report (Date of earliest event reported) April 1, 1998



                              NEOTHERAPEUTICS, INC.
             (Exact name of registrant as specified in its charter)




          Delaware                    0-28782             93-0979187
(State or other jurisdiction        (Commission         (IRS Employer
     of incorporation)              File Number)     Identification No)




    157 Technology Drive, Irvine, California              92618
    (Address of principal executive offices)            (Zip Code)




        Registrant's telephone number, including area code (714) 788-6700




                                 Not Applicable
          (Former name or former address, if changed since last report)


                             Exhibit Index on Page 3



<PAGE>   2

ITEM 5.  OTHER EVENTS

        Reference is made to the press releases issued to the public by the
Registrant on April 1, 1998, the text of which are attached hereto as Exhibits
99.1 and 99.2, for a description of the events reported pursuant to this Form
8-K.

        Reference is made to the web page transcript to be used by the
Registrant on the Registrant's world wide web page attached hereto as Exhibit
99.3 and is incorporated herein by reference.


ITEM 7.  EXHIBITS


<TABLE>
<CAPTION>
        Exhibits:
        ---------
<S>                   <C>     
          99.1        Press Release dated April 1, 1998.
          99.2        Press Release dated April 1, 1998.
          99.3        Transcript of registrant's web site.
</TABLE>




                                    SIGNATURE

        Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                       NEOTHERAPEUTICS, INC.



Date:  April 1, 1998                   By:  /s/ SAMUEL GULKO
                                          --------------------------------------
                                          Samuel Gulko
                                          Chief Financial Officer

                                       2

<PAGE>   3

                                  EXHIBIT INDEX



<TABLE>
<CAPTION>
             Exhibits              Description
             --------              -----------
<S>                           <C>     
               99.1          Press Release dated April 1, 1998.
               99.2          Press Release dated April 1, 1998.
               99.3          Transcript of registrant's web site.
</TABLE>



                                       3





<PAGE>   1
                                                                    EXHIBIT 99.1


FOR IMMEDIATE RELEASE



                    NEOTHERAPEUTICS ANNOUNCES EQUITY-BASED LINE OF CREDIT


IRVINE, California - April 1, 1998 - NeoTherapeutics, Inc. (NASDAQ: NEOT and
NEOTW) announced today that the Company has secured an equity-based $15 million
line of credit, with a single institutional investor, primarily for testing of
its lead compound, AIT-082, and the development of other key technology. AIT-082
is currently in Phase I clinical trials as a potential treatment for Alzheimer's
disease.

Under this privately-placed equity offering, NeoTherapeutics has the right,
subject to certain conditions, to draw up to $15 million cash in exchange for
NeoTherapeutics common stock. "This is an important and unique strategic funding
for the Company, as it provides us with significant cash reserves to continue
testing AIT-082. Essentially, it allows us to fund our testing on an on-going
basis and assures us that the funds will be available when needed," said Dr.
Alvin Glasky, Chief Executive Officer of NeoTherapeutics. "Entering into this
agreement also provides us with greater flexibility by strengthening our
financial position as we evaluate our other products in development."

Samuel Gulko, CFO, commented, "This financing
 will allow NeoTherapeutics to
continue to execute its business plan and accelerate our product development
timetable. Coupled with existing cash reserves, this innovative structure gives
NeoTherapeutics the ability to take advantage of potentially favorable market
conditions. Further, it protects our shareholders by leaving the timing and
amount of the draw to the discretion of NeoTherapeutics".

The equity line will remain available for a period of 30 months, and the
decision to draw any funds and the timing and amount for any such draw is solely
at the Company's discretion, subject to the satisfaction of certain conditions,
including the registration of the shares, which will be issued at a 12% discount
to the then current market price.

AIT-082, NeoTherapeutics' lead compound for Alzheimer's disease, is believed by
the Company to be the first orally active drug to enter human clinical trials
that is specifically designed to address the issue of nerve regeneration.
AIT-082 has been in Phase I clinical trials since March 1997 and plans are being
made to conduct the first Phase II human study this summer.



<PAGE>   2

In pre-clinical testing, AIT-082 has been demonstrated to reduce, delay or
prevent memory deficits in animals. In addition, AIT-082 has shown in laboratory
and animal studies to induce the production of three neurotrophic factors, NGF,
NT-3 and bFGF. These three factors have been reported to induce the
multiplication and functional maturation of cholinergic neurons, those known to
die in Alzheimer's disease.


                                    - more -



<PAGE>   3
NeoTherapeutics Announces Equity-Based Line of Credit
April 1, 1998
Page Two



NeoTherapeutics, Inc., based in Irvine, CA, is a publicly traded
biopharmaceutical company dedicated to the discovery and development of drugs
that act on the central nervous system to repair nerve cells and treat
neurodegenerative diseases and conditions such as Alzheimer's disease, memory
deficits associated with aging, spinal cord injury, Parkinson's disease, stroke
and migraine. NeoTherapeutics' products are orally administered and based on
patented technologies.

This press release contains forward-looking statements regarding future events
and the future performance of NeoTherapeutics that involve risks and
uncertainties that could cause actual results to differ materially. These risks
include, but are not limited to, the biological activity, side effect profile
and efficacy of AIT-082, the early stage of product development, the initiation
and completion of additional clinical trials and the dependence on third parties
for clinical testing, manufacturing and marketing. These risks are described in
further detail in the Company's annual and quarterly reports filed with the
Securities and Exchange Commission.

- -----------------------------------------------
SOURCE: NEOTHERAPEUTICS, INC.
Contact:   Carol Hess                   Bob Ferris
           Investor Relations           President, Investor & Corp. Relations
           NeoTherapeutics, Inc.        Ruder-Finn, Inc.
           Tel:  714-788-6700           Tel:  212-715-1574
           Fax: 714-788-6706            Fax: 212-715-1660



                                      # # #




<PAGE>   1
                                                                    EXHIBIT 99.2



Contact:

NeoTherapeutics, Inc.                                           Ruder-Finn, Inc.
Carol Hess, Investor Relations                                        Bob Ferris
Tel:  714-788-6700                                            Tel:  212-715-1574
Fax: 714-788-6706                                             Fax:  212-715-1660



FOR IMMEDIATE RELEASE

                NEOTHERAPEUTICS, INC. REPORTS FOURTH QUARTER AND
                          FISCAL 1997 FINANCIAL RESULTS

IRVINE, CA, APRIL 1, 1997 - NeoTherapeutics, Inc. (Nasdaq: NEOT & NEOTW) today
reported financial results for the fourth quarter and year ended December 31,
1997.

For the fourth quarter ended December 31, 1997, the Company reported a net loss
of $2,317,852 or $(0.42) per share, compared with a net loss of $508,129 or
$(0.10) per share, in the fourth quarter of 1996.

For the year ended December 31, 1997, the Company reported a net loss of
$6,161,541 or $(1.14) per share, compared with a net loss of $1,038,875 or
$(0.31) per share, for the year ended December 31, 1996. The increase in net
loss was principally due to increased costs and expenses associated with the
commencement of clinical trials regarding the Company's lead product, as well as
personnel additions, salary increases, facilities rent, consulting fees and
insurance costs as the Company continues to expand its operations.

The Company's lead product, AIT-082, has been in Phase I clinical trials as a
potential treatment for Alzheimer's
 disease. The three human trials completed to
date have demonstrated no adverse reactions and have shown that AIT-082 is
orally absorbed and remains in the blood for sufficiently long periods to allow
the potential for once daily dosing. The first Phase II efficacy study with
AIT-082 is planned to begin this summer.

The Company also announced that it has secured an equity-based $15 million line
of credit primarily for funding additional testing of AIT-082 and the
development of other technology.

In order to provide shareholders with additional information on Company
operations, the Company has expanded its web site at www.neotherapeutics.com. A
new page has been added which will be updated periodically to discuss "What's
Going On."

NeoTherapeutics is engaged in the discovery and development of drugs that act on
the central nervous system to repair nerve cells and treat neurodegenerative
diseases and conditions such as Alzheimer's disease, memory deficits associated
with aging, spinal cord injury, Parkinson's disease, stroke and migraine.
NeoTherapeutics' products are orally administered and based on patented
technologies.


<PAGE>   2

This press release contains forward-looking statements regarding future events,
such as the timing of future clinical trials, that involve risks and
uncertainties that could cause actual results to differ materially. These risks
include, but are not limited to, the biological activity, side effect profile
and efficacy of AIT-082, the early stage of product development, the potential
need for additional funding, the initiation and completion of clinical trials
and dependence on third parties for clinical testing, manufacturing and
marketing. These risks are described in further detail in the Company's annual
and quarterly reports filed with the Securities and Exchange Commission.


                           - FINANCIAL CHARTS FOLLOW -



<PAGE>   3
                     NEOTHERAPEUTICS, INC. AND SUBSIDIARIES
                        (A DEVELOPMENT STAGE ENTERPRISE)

                         SUMMARY STATEMENT OF OPERATIONS



<TABLE>
<CAPTION>
                                               Three Months Ended                
                                                  December 31,                      Year Ended  
                                                  (Unaudited)                       December 31, 
                                            1997               1996             1997              1996
                                         -----------       -----------       -----------       -----------
<S>                                      <C>               <C>               <C>               <C>        
REVENUES:                                $        --       $        --       $        --       $        --

EXPENSES:
Research and development                   1,751,194           410,587         4,508,255           615,485
General and administration expense           668,173           351,329         2,341,276           659,895
                                         -----------       -----------       -----------       -----------

LOSS FROM OPERATIONS                      (2,419,367)         (761,916)       (6,849,531)       (1,275,380)

Other income (expense), net,
        principally interest                 101,515           253,787           687,990           236,505
                                         -----------       -----------       -----------       -----------

Net loss                                 $(2,317,852)      $  (508,129)      $(6,161,541)      $(1,038,875)
                                         ===========       ===========       ===========       ===========

Net loss per share                       $     (0.42)      $     (0.10)      $     (1.14)      $     (0.31)
                                         ===========       ===========       ===========       ===========

Weighted average shares outstanding        5,465,807         5,287,997         5,405,831         3,374,549
                                         ===========       ===========       ===========       ===========
</TABLE>




                              SUMMARY BALANCE SHEET


<TABLE>
<CAPTION>
                                              December 31, 1997       December 31, 1996
                                              -----------------       -----------------
<S>                                              <C>                    <C>        
Cash and cash equivalents                        $ 6,063,347            $ 9,995,062
Marketable securities and other investments        3,068,375              7,448,546
All other assets, net                              4,066,751                535,668
                                                 -----------            -----------
                                                                      
Total assets                                     $13,198,473            $17,979,276
                                                 ===========            ===========
                                                                      
Current liabilities                                2,478,529              1,357,196
Long term liabilities                                176,549                     --
Stockholders equity (deficit)                     10,543,395             16,622,080
                                                 -----------            -----------
                                                                      
Total liabilities and stockholders equity        $13,198,473            $17,979,276
                                                 ===========            ===========
</TABLE>

                                                                   




<PAGE>   1
                                                                    EXHIBIT 99.3


                                WHAT'S GOING ON ?

Message from the President (April 1, 1998)

With the advent of the Electronic Age and the Internet, we are in a new age of
communication. Just as NeoTherapeutics is on the cutting edge in biomedical
science, we believe that it would be appropriate for us to try new cutting edge
avenues of communication with investors and individuals who have an interest in
our Company and technology. Thus, we are testing this new format for
communication. This page on our website will provide a means of discussing
matters of concern to our investors as well as affording the Company an
opportunity to comment on issues. We also hope to be able to elaborate on
different aspects of our technology from time to time. In addition to sending
our shareholders quarterly reports timed to our Form 10-Q filings with the SEC,
we will publish those quarterly letters on this site. It is our intent to have
at least one additional posting at this site between each quarterly report. Many
investors have commented to us that they have been concerned that the flow of
information on the status of the Company is not generally available unless the
investor continually calls the Company. Hopefully this means of communication

will prove to be more convenient to our investors while providing timely
information.

NeoTherapeutics has filed the Annual Report on Form 10-KSB with the SEC. It
contains our audited financial statements and other important information. I
would like to elaborate on two areas of that document - our clinical program and
the financial status of the Company.

The first is the status of our development program. Three Phase I clinical
studies have been completed. Traditionally, Phase I studies provide information
necessary to design Phase II efficacy studies and are not usually published
independent research projects.

The first Phase I human clinical study was conducted in Canada with 10
Alzheimer's disease volunteers and involved treatment with a single escalating
oral dose of AIT-082. The volunteers received a single dose of placebo, 500,
1000, 2000 and then 4000 milligrams of AIT-082 at 3-7 day intervals. The
available data from that study indicated that AIT-082 produced no serious
adverse reactions, that AIT-082 was orally absorbed and remained in the blood
system for sufficiently long duration to suggest the possibility that once daily
dosage was possible. The results of the memory function tests suggested that
lower doses of AIT-082 should be studied. To that objective, the same 10
patients enrolled in the second Phase I Canadian study in which the single doses
studied were 50, 


                                       1

This page contains forward-looking statements regarding future events and the
future performance of NeoTherapeutics that involve risks and uncertainties that
could cause actual results to differ materially. These risks include, but are
not limited to, the biological activity, side effect profile and efficacy of
AIT-082, the early stage of product development, the initiation and completion
of additional clinical testing and the dependence on third parties for clinical
testing, manufacturing and marketing. These risks are described in further
detail in the Company's annual and quarterly reports filed with the Securities
and Exchange Commission.


<PAGE>   2
150, 250 and 500 milligrams. The data from these studies are currently being
audited and analyzed.

The first Phase I U.S. study was initiated after U.S. FDA approval of our IND
and was conducted under the auspices of the National Institute on Aging and the
Alzheimer's Disease Clinical Study ("ADCS") involving 8 healthy elderly
volunteers. This was a randomized double blind clinical study with one single
dose of drug or placebo being orally administered. The dose range was from 0.6
to 20 milligrams per kilo body weight. While the data from that study has not
been audited and completely analyzed, it demonstrated that AIT-082 produced no
serious adverse reactions, that AIT-082 was rapidly absorbed after oral
administration, and that AIT-082 remained in the blood stream sufficiently long
to allow the potential for once a day dosage. A follow-up study with Alzheimer's
patient volunteers is being planned by the ADCS for early summer.

In February, 1998, NeoTherapeutics initiated a double-blind placebo-controlled
clinical Phase I study with 24 healthy elderly volunteers who received doses of
AIT-082 daily for 7 consecutive days. This study is the first to administer
multiple doses of AIT-082 to humans. The administration of drug to the patients
is complete but results are not anticipated for several months due to the need
to complete the blood analysis, audit the clinical records and then analyze the
data.

Plans are in progress for initiating the first classical Phase II efficacy
trials pending the outcome of the current and completed clinical studies. While
we believe that much valuable information can be obtained from this study, it
should be realized that it has taken at least 90 days of treatment for any of
the currently marketed drugs to demonstrate statistically significant
differences between drug and placebo-treated patients. We must maintain
reasonable, modest expectations regarding the potential efficacy results from
the AIT-082 clinical trials because Alzheimer's disease develops over a long
period of time and the deficits observed involve many biological systems in the
body that must be improved if efficacy is to be observed.

The second topic I wish to discuss is the financial status of the Company. From
the annual financial statements, as of December 31, 1997, NeoTherapeutics had
approximately $9 million remaining from the public offering of September 1996.
During a recent presentation to institutional investors in New York, an
interesting observation was offered by one of the attendees. They commented that
in the 18 months since the offering, management has accomplished most of the
goals established at that time and the Company still had money left. This
distinguished us from most biotech companies who manage to spend all their money
and attain only a few of their promised goals. I 



                                       2



This page contains forward-looking statements regarding future events and the
future performance of NeoTherapeutics that involve risks and uncertainties that
could cause actual results to differ materially. These risks include, but are
not limited to, the biological activity, side effect profile and efficacy of
AIT-082, the early stage of product development, the initiation and completion
of additional clinical testing and the dependence on third parties for clinical
testing, manufacturing and marketing. These risks are described in further
detail in the Company's annual and quarterly reports filed with the Securities
and Exchange Commission.


<PAGE>   3
think that the comment from this investor reflects favorably upon the
performance of all of our employees, who are focused on the key objectives that
have to be accomplished and share a mutual concern that the financial resources
be used judiciously.

As part of a careful financial plan, management is pleased to have executed an
Agreement, with a single institutional investor, which provides for the Company,
at its sole discretion, to sell ("put"), at future market prices, up to $15
million of its common stock, subject to a minimum put of $1 million over the
thirty month duration of the Agreement. Details of this Agreement are further
explained in our Form 10-KSB.

In order to accelerate the Company's timetable for AIT-082 and our other
targeted products in development, it was necessary for the Company to augment
our capital resources. The Company will have the opportunity to complete
additional clinical testing of AIT-082 which could have the potential of
increasing the value of any possible future product licensing agreement. This
includes not only maximizing up-front payments but developing the type of
strategic alliance that would be able to advance AIT-082 to marketability in the
most expeditious manner. Management remains committed to maximizing the value of
our technology base for the benefit of our shareholders.

Management and the technical staff are excited about the progress that our
Company, our technology platform and our lead product AIT-082 have been making
in the past 6-12 months. We believe that this pace will continue and hope that
we can share a number of additional significant milestones with our shareholders
over the next year.


Sincerely,   Alvin J. Glasky, President



                                       3


This page contains forward-looking statements regarding future events and the
future performance of NeoTherapeutics that involve risks and uncertainties that
could cause actual results to differ materially. These risks include, but are
not limited to, the biological activity, side effect profile and efficacy of
AIT-082, the early stage of product development, the initiation and completion
of additional clinical testing and the dependence on third parties for clinical
testing, manufacturing and marketing. These risks are described in further
detail in the Company's annual and quarterly reports filed with the Securities
and Exchange Commission.