<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                  FORM 10-Q/A-1

(Mark One)

[X]      QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
         SECURITIES EXCHANGE ACT OF 1934

         For the quarterly period ended April 30, 1999

[ ]      TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
         SECURITIES EXCHANGE ACT OF 1934

         For the transition period from ____________________ to _______________

                          Commission File Number 1-8366

                         POLYDEX PHARMACEUTICALS LIMITED
             (Exact Name of Registrant as Specified in Its Charter)

    Commonwealth of the Bahamas                                 None
--------------------------------------------------------------------------------
(State or Other Jurisdiction                             (I.R.S. Employer
 of Incorporation or Organization)                      Identification No.)

421 Comstock Road, Toronto, Ontario, Canada                   M1L 2H5
--------------------------------------------------------------------------------
(Address of Principal Executive Offices)                     (Zip Code)

Registrant's Telephone Number, Including Area Code   (416) 755-2231

--------------------------------------------------------------------------------
Former Name, Former Address and Former Fiscal Year, if Changed Since Last Report

         Indicate by check whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. Yes X  No
                                      ---   ---

         Indicate the number of shares outstanding of each of the issuer's
classes of common shares, as of the latest practicable date.

Common Shares, $.016 Par Value                        3,016,917 shares
------------------------------                     ---------------------------
             (Title of Class)                      (Outstanding at May 6, 1999)

<PAGE>

     The Registrant hereby amends its Form 10-Q for the quarterly period
ended April 30, 1999 to restate the following line items on its consolidated
balance sheets: "Property, plant and equipment, net" from $4,438,883 to
$4,438,993, and "Due from Novadex Corp." from $858,574 to $658,574.

                                     -2-
<PAGE>

                                     PART I
                              FINANCIAL INFORMATION

ITEM 1.           CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED).


POLYDEX PHARMACEUTICALS LIMITED AND
SUBSIDIARIES

Consolidated Balance Sheets
(Expressed in United States dollars)

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------
                                                                     (Unaudited)
                                                                       April 30           April 30
                                                                           1999               1998
---------------------------------------------------------------------------------------------------
<S>                                                           <C>                  <C>
ASSETS

Current assets:
       Cash                                                   $   434,908          $   655,131
       Trade Accounts receivable                                1,244,633              984,934
       Inventories                                              2,005,460            1,917,278
       Prepaid expenses and other current assets                   82,898               69,188
       ----------------------------------------------------------------------------------------------------------------
                                                                3,767,899            3,620,531

Property, plant and equipment, net                              4,438,993            4,233,144
Patents, net                                                      167,232              166,404
Due from Novadex Corp.                                            658,574              658,574
Due from shareholder                                              887,032              903,307
Deferred income taxes                                             580,715              776,000
Other assets                                                       74,769               92,574
---------------------------------------------------------------------------------------------------
                                                              $10,575,214          $10,456,264
---------------------------------------------------------------------------------------------------
</TABLE>


                                       -3-

<PAGE>

<TABLE>
<CAPTION>

                                                                                        (Unaudited)
                                                                                          April 30          January 31
                                                                                              1999                1999
-----------------------------------------------------------------------------------------------------------------------
<S>                                                                               <C>                  <C>
LIABILITIES AND SHAREHOLDERS' EQUITY

Current liabilities:
       Accounts payable                                                           $      1,104,379     $     1,189,886
       Accrued liabilities                                                                 461,677             466,556
       Income taxes payable                                                                 57,601              51,779
       Current portion of long-term debt                                                   125,822             107,994
       Current portion of mandatorily redeemable capital stock                              50,000             100,000
       ----------------------------------------------------------------------------------------------------------------

                                                                                         1,799,479           1,916,215

Long-term debt                                                                             531,238             521,170
Due to shareholder                                                                         648,300            637,017
Deferred gain                                                                              657,550             659,018
Deferred income taxes                                                                       85,473             148,083
Mandatorily redeemable capital stock                                                       300,000             300,000
-----------------------------------------------------------------------------------------------------------------------

Total liabilities                                                                        4,022,040           4,181,503

Redeemable capital stock (93,899 common shares; 99/01/31 - 93,899)                       1,028,733           1,028,733
Shareholders' equity:
       Capital stock:
            Authorized:
                 100,000 A preferred shares of $0.10 each 899,400 B preferred
                 shares of $0.0167 each 4,000,000 common shares of $0.0167 each
            Issued and outstanding:
                 899,400 B preferred shares                                                 15,010              15,010
                 2,923,018 common shares (99/01/31 - 2,923,018)                             48,552              48,552
       Contributed surplus                                                              22,464,783          22,464,783
       Deficit                                                                         (16,270,843)        (16,498,775)
       Accumulated other comprehensive income                                             (733,061)           (783,542)
       ----------------------------------------------------------------------------------------------------------------

                                                                                         5,524,441           5,246,028
-----------------------------------------------------------------------------------------------------------------------

                                                                                  $     10,575,214     $    10,456,264
-----------------------------------------------------------------------------------------------------------------------

</TABLE>

                                       -4-

<PAGE>

POLYDEX PHARMACEUTICALS LIMITED AND
SUBSIDIARIES

Consolidated Statements of Operations (Unaudited)
(Expressed in United States dollars)

<TABLE>
<CAPTION>

---------------------------------------------------------------------------------------------------
                                                                  Quarter Ended      Quarter Ended
                                                                       April 30           April 30
                                                                           1999               1998
---------------------------------------------------------------------------------------------------
<S>                                                           <C>                  <C>
Sales                                                         $       3,170,641    $     2,930,964
Cost of products sold                                                 2,144,107          2,015,282
---------------------------------------------------------------------------------------------------

                                                                      1,026,534            915,682

Expenses:

       General and administrative                                       397,808            373,147
       Depreciation                                                     123,683            108,456
       Research and development                                          79,504             42,403
       Interest expense                                                  34,734             34,906
       Selling and promotion                                             19,720             44,496
       Amortization                                                       5,474              9,072
       --------------------------------------------------------------------------------------------

                                                                        660,923            612,480
---------------------------------------------------------------------------------------------------

Income from operations                                                  365,611            303,202

Other income:
       Gain on sale of equipment                                              -              6,669
       Interest and other                                                 8,618             18,963
       --------------------------------------------------------------------------------------------

                                                                          8,618             25,632
---------------------------------------------------------------------------------------------------

Income before the undernoted                                            374,229            328,834

Provision for income taxes                                             (146,297)          (152,821)
---------------------------------------------------------------------------------------------------

Income for the period                                         $         227,932    $       176,013
---------------------------------------------------------------------------------------------------


Per share information:

       Earnings per common share for the period:
               Basic                                          $            0.08    $          0.06
               Diluted                                        $            0.08    $          0.06

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


Weighted average number of common shares
       outstanding for the period                                     3,016,917          2,996,907
---------------------------------------------------------------------------------------------------

</TABLE>

                                       -5-

<PAGE>

POLYDEX PHARMACEUTICALS LIMITED AND
SUBSIDIARIES

Consolidated Statements of Shareholders' Equity and Comprehensive Income
(Unaudited)
(Expressed in United States dollars)

<TABLE>
<CAPTION>

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

                                                                     Quarter Ended        Quarter Ended
                                                                          April 30             April 30
                                                                              1999                 1998
--------------------------------------------------------------------------------------------------------
<S>                                                             <C>                  <C>
Preferred Shares:

         Balance, beginning of period                           $           15,010   $           15,010
         Private placement of preferred shares                                   -                    -
         -----------------------------------------------------------------------------------------------

         Balance, end of period                                 $           15,010   $           15,010
--------------------------------------------------------------------------------------------------------

Common Shares:
         Balance, beginning of period                           $           48,552   $           47,283
         Exercise of options                                                     -                    -
         -----------------------------------------------------------------------------------------------

         Balance, end of period                                 $           48,552   $           47,283
--------------------------------------------------------------------------------------------------------

Contributed Surplus:
         Balance, beginning of period                           $       22,464,783   $       21,826,025
         Exercise of options                                                        -                 -
         -----------------------------------------------------------------------------------------------

         Balance, end of period                                 $       22,464,783   $       21,826,025
--------------------------------------------------------------------------------------------------------

Deficit:
         Balance, beginning of period                           $      (16,498,775)  $      (17,071,168)
         Net income for the period                                         227,932              176,013
         -----------------------------------------------------------------------------------------------

         Balance, end of period                                 $      (16,270,843)  $      (16,895,155)
--------------------------------------------------------------------------------------------------------

Accumulated Other Comprehensive Income:
         Balance, beginning of period                           $         (783,542)  $         (665,768)
         Currency translation adjustment for the period                     50,481               19,969
         -----------------------------------------------------------------------------------------------

         Balance, end of period                                 $         (733,061)  $         (645,799)
--------------------------------------------------------------------------------------------------------

Comprehensive Income for the period:
         Net income (loss) for the period                       $          227,932   $          176,013
         Currency translation adjustment for the period                     50,481               19,969
         -----------------------------------------------------------------------------------------------

                                                                $          278,413   $          195,982
--------------------------------------------------------------------------------------------------------

</TABLE>

                                       -6-

<PAGE>

POLYDEX PHARMACEUTICALS LIMITED AND
SUBSIDIARIES

Consolidated Statements of Cash Flows
(Expressed in United States dollars)

<TABLE>
<CAPTION>

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

                                                                                 Year to Date         Year to Date
                                                                                     April 30             April 30
                                                                                         1999                 1998
-------------------------------------------------------------------------------------------------------------------
<S>                                                                        <C>                  <C>
Cash provided by (used in):

Operating activities:
       Net income for the period                                           $          227,932   $          176,013
       Add (deduct) items not affecting cash:
            Depreciation and amortization                                             129,157              117,528
            Deferred income taxes                                                     135,304              152,821
            Loss (gain) on sale of equipment                                                -               (6,669)
            Legal expenses charged to deferred gain                                    (1,468)                 (58)
       Change in non-cash operating working capital                                  (416,466)            (251,383)
       ------------------------------------------------------------------------------------------------------------

                                                                                       74,459              188,252
       ------------------------------------------------------------------------------------------------------------

Investing activities:
       Additions to property, plant and equipment and patents                        (298,617)            (171,222)
       Proceeds from sale of equipment                                                      -                9,500
       Repayment of due from shareholder, net                                          16,005                4,344
       ------------------------------------------------------------------------------------------------------------

                                                                                     (282,612)            (157,378)
       ------------------------------------------------------------------------------------------------------------

Financing activities:
       Repayment of loans payable                                                      (8,481)                   -
       Repayment of long-term debt                                                    (24,526)             (14,164)
       Proceeds from long-term debt                                                    52,422               20,000
       Payment of mandatorily redeemable capital stock                                (50,000)                   -
       Repayment of advances from shareholder, net                                     11,283               11,599
       ------------------------------------------------------------------------------------------------------------

                                                                                      (19,302)              17,435

       Effect of exchange rate changes on cash                                          7,232                8,553
-------------------------------------------------------------------------------------------------------------------

Increase (decrease) in cash position                                                 (220,223)              56,862

Cash, beginning of period                                                             655,131              288,527
-------------------------------------------------------------------------------------------------------------------

Cash, end of period                                                        $          434,908   $          345,389
-------------------------------------------------------------------------------------------------------------------

</TABLE>

                                       -7-

<PAGE>

POLYDEX PHARMACEUTICALS LIMITED AND
SUBSIDIARIES

Segmented Information (Unaudited)
(Expressed in United States dollars)

<TABLE>
<CAPTION>

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

                                                                                Quarter Ended          Quarter Ended
                                                                                     April 30               April 30
                                                                                         1999                   1998
---------------------------------------------------------------------------------------------------------------------
<S>                                                                      <C>                     <C>
SALES:

         Dextran                                                         $          1,115,422    $         1,034,308
         Veterinary products                                                        2,055,219              1,896,656
         ------------------------------------------------------------------------------------------------------------

         Total consolidated sales                                        $          3,170,641    $         2,930,964
---------------------------------------------------------------------------------------------------------------------


INCOME FROM OPERATIONS:

         Dextran                                                         $            375,370    $           334,185
         Veterinary products                                                          169,406                139,140
         ------------------------------------------------------------------------------------------------------------

         Total income from operations from segments                                   544,776                473,325
         Less:  Unallocated corporate expenses                                        179,165                170,123
         ------------------------------------------------------------------------------------------------------------

         Total consolidated income from operations                       $            365,611    $           303,202
---------------------------------------------------------------------------------------------------------------------


ASSETS:
         Dextran                                                         $          5,079,095    $         4,469,019
         Veterinary products                                                        4,090,343              3,781,737
         ------------------------------------------------------------------------------------------------------------

         Total assets from segments                                                 9,169,438              8,250,756
         Corporate assets                                                           1,405,776              1,640,342
         ------------------------------------------------------------------------------------------------------------

         Total consolidated assets                                       $         10,575,214    $         9,891,098
---------------------------------------------------------------------------------------------------------------------

</TABLE>

                                       -8-

<PAGE>

                                   SIGNATURES

         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.

Date:  June 16, 1999

                              POLYDEX PHARMACEUTICALS LIMITED
                              (Registrant)

                           By /s/ George G. Usher
                              ----------------------------------------------
                              George G. Usher, Chairman, President and Chief
                              Executive Officer
                              (Principal Executive Officer)

                           By /s/ Sharon L. Wardlaw
                              ----------------------------------------------
                              Sharon L. Wardlaw, Treasurer, Secretary and
                              Chief Financial and Accounting Officer
                              (Principal Financial Officer)

                                      -9-