Exhibit 10.41

                 FIRST AMENDMENT TO LOAN AND SECURITY AGREEMENT
                               AND LIMITED WAIVER


     This First  Amendment to Loan and  Security  Agreement  and Limited  Waiver
("Amendment") is dated as of May 1, 1997, and entered into by and between HELLER
FINANCIAL,  INC.  ("Lender")  and MEDTOX  SCIENTIFIC,  INC.  (formerly  known as
EDITEK,  Inc.),  MEDTOX  LABORATORIES,   INC.  (formerly  known  as  Psychiatric
Diagnostic Laboratories of America, Inc.) and MEDTOX DIAGNOSTICS, INC. (formerly
known as diAGnostix, Inc.) (collectively, "Borrowers").

         WHEREAS,  Lender and  Borrowers  have  entered into a Loan and Security
Agreement, (the "Agreement") dated January 30, 1996; and

         WHEREAS,  the  shareholders  of Borrowers have approved a change in the
name of each Borrower and the Lender and Borrowers desire to amend the Agreement
to acknowledge said name changes; and

         WHEREAS,  certain Events of Default are in existence  under  subsection
8.1(C) of the Agreement as a result of Borrowers' breach of (i) the Tangible Net
Worth  covenant  contained in subsection 6.1 for the all quarters in Fiscal Year
1996 and for the quarter ended March 31, 1997;  (ii) the Minimum EBIDTA covenant
contained in subsection 6.2 for all the monthly  periods in Fiscal Year 1996 and
for the twelve  (12)  month  period  ended  March 31,  1997;  (iii) the Ratio of
Indebtedness to Tangible Net Worth covenant  contained in subsection 6.3 for all
quarters in Fiscal Year 1996 and for the quarter ended March 31, 1997;  (iv) the
Capital  Expenditure Limits covenant contained in subsection 6.4 for Fiscal Year
1996; (v) the Fixed Charge Coverage covenant contained in subsection 6.5 for all
monthly  periods in Fiscal Year 1996 and for the twelve (12) month  period ended
March 31, 1997; and (vi) the Interest Coverage covenant  contained in subsection
6.6 for all month  periods in Fiscal Year 1996 and the twelve (12) month  period
ended March 31, 1997 (collectively, the "Existing Events of Default").

     WHEREAS,  Borrowers have requested that Lender waive the Existing Events of
Default; and

         WHEREAS,  Lender has agreed to waive the existing Events of Default and
amend the Agreement in certain respects, subject to the terms and conditions set
forth herein.

         NOW THEREFORE, in consideration of the mutual conditions and agreements
set forth in the  Agreement  and this  Amendment,  and other  good and  valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties, intending to be legally bound, hereby agree as follows:

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                             ARTICLE I. DEFINITIONS

     Section 1.01. Definitions. Capitalized terms used in this Amendment, to the
extent not  otherwise  defined  herein,  shall have the same  meanings as in the
Agreement, as amended hereby.

                             ARTICLE II. AMENDMENTS

The Agreement is hereby amended as follows:

         Section 2.01.  Amendment to  Subsection  1.1 "Certain  Defined  Terms".
Subsection 1.1 is hereby amended by adding,  in proper  alphabetical  order, the
following new definitions:

     "Diagnostics"  means MEDTOX Diagnostics,  Inc. (f/k/a diAGnostix,  Inc.), a
Delaware corporation, and its successors and permitted assigns.
     
     "Medtox" means MEDTOX  Scientific,  Inc.  (f/k/a EDITEK,  Inc.), a Delaware
corporation, and its successors and permitted assigns.

     "MLI"  means  MEDTOX  Laboratories,   Inc.  (f/k/a  Psychiatric  Diagnostic
Laboratories of America,  Inc.), a Delaware corporation,  and its successors and
permitted assigns.

         Section 2.01.  Amendment to Subsection  2.1(C)  "Eligible  Collateral".
Subsection  2.1(C) is hereby  amended by adding the following  paragraph (18) to
the end of said subsection:

     (18) Accounts due from Substance  Abuse  Management,  Inc.  ("SAMI") to the
extent that such Accounts exceed in the aggregate, at any date of determination,
an amount equal to the lesser of (i) twelve  percent  (12%) of the  aggregate of
Accounts of all Borrowers at said date or (ii) $590,000.

     Section 2.02. Amendment to Subsection 2.2(A) "Rate of Interest". Subsection
2.2 is hereby amended and restated as follows:

                  (A) Rate of  Interest.  The Loans  and all  other  Obligations
         shall  bear  interest  from the date such  Loans are made or such other
         Obligations  become  due to the date paid at a rate per annum  equal to
         two percent  (2.00%) plus the Base Rate with  respect to the  Revolving
         Loan,  (ii) two and  one-half  percent  (2.50%) plus the Base Rate with
         

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         respect to Term Loan A and (iii) three  percent  (3.00%)  plus the Base
         Rate with  respect  to Term  Loan B (the  "Interest  Rate").  After the
         occurrence and during the continuance of an Event of Default, the Loans
         and all other Obligations shall, at Lender's option, bear interest at a
         rate per annum equal to three  percent  (3.00%) plus the Interest  Rate
         (the "Default Rate").

     Section 2.03.  Amendment to Subsection  5.1(F) "Borrowing Base Certificate,
Registers and  Journals".  Subsection  5.1(F) is hereby  amended and restated as
follows:

         (F) Borrowing Base Certificates, Registers and Journals. On the Closing
         Date and within five (5) Business Days after the last day of each month
         and from time to time upon the request of Lender,  each Borrower  shall
         deliver to Lender:  (1) a Borrowing Base Certificate  updated since the
         date of the prior Borrowing Base Certificate, together with a report of
         the  outstanding  balance of the Revolving  Loan owing by such Borrower
         and  the  amount  of all  intercompany  advances  owing  by and to such
         Borrower; (2) an invoice register or sales journal describing all sales
         of such Borrower since the date of the prior invoice register,  in form
         and  substance  satisfactory  to Lender,  and,  if Lender so  requests,
         copies  of  invoices  evidencing  such  sales and  proofs  of  delivery
         relating  thereto;  (3) a cash  receipts  journal  describing  all cash
         receipts  of such  Borrower  since the date of the prior cash  receipts
         journal;  (4) an aged trial balance of all its then existing  Accounts;
         and  (5) an  aged  trial  balance  of all its  then  existing  accounts
         payable; and (6) a detailed inventory listing and cover summary report.
         All such reports shall be in form and substance satisfactory to Lender.
         Notwithstanding the foregoing, effective May 1, 1997, and until further
         notice  from  Lender,   Borrowers  shall  deliver  the  Borrowing  Base
         Certificate  referred to in clause (1) above to Lender on each Business
         Day and the items  referred to in clauses  (2),  (3),  (4), (5) and (6)
         above to Lender  within  five (5)  Business  Days after the last day of
         each month.

     Section 2.04. Amendment to Subsection 6.1 "Tangible Net Worth".  Subsection
6.1 is hereby amended and restated as follows:

                  6.1 Tangible Net Worth.  Borrowers shall at all times maintain
         a  consolidated  Tangible  Net Worth of at least the  amounts set forth
         below at the end of each quarter of a Fiscal Year set forth below.


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                  Fiscal Quarter                                  Amount

                  March 31, 1996                              $  500,000
                  June 30, 1996                               $1,000,000
                  September 30, 1996                          $1,500,000
                  December 31, 1996                           $2,000,000
                  March 31, 1997                              $2,500,000
                  June 30, 1997                               $  180,000
                  September 30, 1997                          $  550,000
                  December 31, 1997                           $  970,000
                  March 31, 1998                              $1,300,000
                  June 30, 1998                               $1,700,000
                  September 30, 1998                          $2,150,000
                  December 31, 1998 and as of the             $2,650,000
                  last day of each fiscal quarter thereafter

     Section 2.05. Amendment to Subsection 6.2 "Minimum EBITDA".  Subsection 6.2
is hereby amended and restated as set forth below:

                  6.2 Minimum  EBITDA.  Borrowers  shall at all times maintain a
         consolidated  EBITDA less  Registration  Payments paid or accrued of at
         least the amounts set forth below for the periods set forth below.
                                             Medtox &
                  Period            Diagnostics    MLI             Consolidated

2 months ended February 29, 1996    $100,000      $    50,000      $   150,000
3 months ended March 31, 1996       $100,000      $   100,000      $   200,000
4 months ended April 30, 1996       $100,000      $   400,000      $   500,000
5 months ended May 31, 1996         $100,000      $   800,000      $   900,000
6 months ended June 30, 1996        $200,000      $ 1,000,000      $ 1,200,000
7 months ended July 31, 1996        $200,000      $ 1,400,000      $ 1,600,000
8 months ended August 31, 1996      $200,000      $ 1,800,000      $ 2,000,000
9 months ended September 30, 1996   $200,000      $ 2,100,000      $ 2,300,000
10 months ended October 31, 1996    $300,000      $ 2,400,000      $ 2,700,000
11 months ended November 30, 1996   $300,000      $ 2,800,000      $ 3,100,000
12 months ended December 31, 1996   $300,000      $ 3,100,000      $ 3,400,000
12 months ended March 31, 1997      $350,000      $ 3,100,000      $ 3,450,000
6 months ended June 30, 1997                                       $ 1,350,000
9 months ended September 30, 1997                                  $ 2,000,000
12 months ended December 31, 1997                                  $ 2,700,000
12 months ended March 31, 1998                                     $ 3,100,000
12 months ended June 30, 1998                                      $ 3,400,000
12 months ended September 30, 1998                                 $ 3,750,000
12 months ended December 31, 1998 and for the 12 months            $ 3,800,000
ended on the last day of each fiscal quarter thereafter

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     Section  2.06.  Amendment  to  Subsection  6.3  "Ratio of  Indebtedness  to
Tangible Net Worth". Subsection 6.3 is hereby amended and restated as follows:

                  6.3 Ratio of Indebtedness to Tangible Net Worth.  The ratio of
         (a) Borrowers' consolidated Indebtedness to (b) Borrowers' consolidated
         Tangible  Net Worth shall be no greater  than the ratio set forth below
         at the end of each quarter of a Fiscal Year set forth below.

                  Fiscal Quarter                      Ratio

                  March 31, 1996                     7.5:1
                  June 30, 1996                      7.5:1
                  September 30, 1996                 7.5:1
                  December 31, 1996                  7.5:1
                  March 31, 1997                     7.5:1
                  June 30, 1997                     28.3:1
                  September 30, 1997                 8.3:1
                  December 31, 1997                  4.5:1
                  March 31, 1998                     3.0:1
                  June 30, 1998                      3.0:1
                  September 30, 1998                 3.0:1
                  December 31, 1998                  3.0:1
                  and as of the last day of each fiscal
                  quarter thereafter

     Section  2.07.   Amendment  to  Subsection  6.5  "Fixed  Charge  Coverage".
Subsection 6.5 is hereby amended and restated as follows:

                  6.5 Fixed Charge  Coverage.  Borrowers  shall not permit their
         consolidated Fixed Charge Coverage for any period set forth below to be
         less than the amount set forth below for such period.


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                           Period                                     Amount

         3 months ended March 31, 1996                                 0.8
         6 months ended June 30, 1996                                  1.0
         9 months ended September 30, 1996                             1.3
         12 months ended December 31, 1996                             1.3
         12 months ended March 31, 1997                                1.3
         6 months ended June 30, 1997                                  0.4
         9 months ended September 30, 1997                             0.8
         12 months ended December 31, 1997                             0.8
         12 months ended March 31, 1998                                1.0
         12 months ended June 30, 1998                                 1.2
         12 months ended September 30, 1998                            1.3
         12 months ended December 31, 1998                             1.4
         and for the 12 months ended on the
         last day of each fiscal quarter thereafter

     Section 2.08. Amendment to Subsection 6.6 "Interest  Coverage".  Subsection
6.6 is hereby amended and restated as follows:

     6.6  Interest  Coverage.  Borrowers  shall not  permit  their  consolidated
Interest  Coverage for any period set forth below to be less than the amount set
forth below for such period.

                           Period                                     Amount

         3 months ended March 31, 1996                                 3.0
         6 months ended June 30, 1996                                  3.4
         9 months ended September 30, 1996                             4.6
         12 months ended December 31, 1996                             5.6
         12 months ended March 31, 1997                                6.0
         6 months ended June 30, 1997                                  1.8
         9 months ended September 30, 1997                             3.2
         12 months ended December 31, 1997                             3.8
         12 months ended March 31, 1998                                4.6
         12 months ended June 30, 1998                                 5.0
         12 months ended September 30, 1998                            5.4
         12 months ended December 31, 1998                             6.0
         and for the 12 months ended on the
         last day of each fiscal quarter thereafter

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                               ARTICLE III. NAMES

         Notwithstanding  anything  contained in the  Agreement to the contrary,
whenever  (i) the  defined  term  "diAGnostix"  appears  therein,  it  shall  be
substituted with the amended defined term  "Diagnostics",  (ii) the defined term
"Editek" appears therein,  it shall be substituted with the amended defined term
"Medtox"  and  (iii)  the  defined  term  "PDLA"  appears  therein,  it shall be
substituted with the amended defined term "MLI".

                               ARTICLE IV. WAIVER

         Lender hereby waives the Existing Events of Default.  This is a limited
waiver  and shall not be deemed  to  constitute  a waiver of any other  existing
Event of Default or any future  breach of the Agreement or any of the other Loan
Documents (including,  without limitation, a breach of the covenants causing the
Existing Events of Default for any periods other than those specified herein).


                            ARTICLE V. MISCELLANEOUS

     Section 5.01. Conditions. The effectiveness of this Amendment is subject to
the  satisfaction of the following  conditions  precedent  (unless  specifically
waived in writing by Lender):

     (a) there shall have occurred no material  adverse  change in the business,
operations,  financial conditions, profits or prospects, or in the Collateral of
Borrowers;

     (b) Borrowers  shall have executed and delivered  such other  documents and
instruments as Lender may require;

(c)      all corporate  proceedings  taken in connection  with the  transactions
         contemplated by this Amendment and all documents, instruments and other
         legal matters  incident thereto shall be satisfactory to Lender and its
         legal counsel; and

     (d)  Borrowers  shall have paid  Lender an  amendment  fee in the amount of
$10,000 and a documentation fee in the amount of $500.

         Section 5.02  Ratification.  The terms and provisions set forth in this
Amendment shall modify and supersede all  inconsistent  terms and provisions set
forth in the Agreement and, except as expressly  modified and superseded by this
Amendment, the terms and provisions of the Agreement, are ratified and confirmed
and shall continue in full force and effect.

         Section 5.03 Corporate  Action The execution,  delivery and performance
of this Amendment have been authorized by all requisite  corporate action on the
part of each  Borrower  and will not violate the  Articles of  Incorporation  or
Bylaws of any Borrower.

<PAGE>

         Section 5.04  Severability.  Any provision of this  Amendment held by a
court of competent  jurisdiction to be invalid or unenforceable shall not impair
or invalidate  the remainder of this  Amendment and the effect  thereof shall be
confined to the provision so held to be invalid or unenforceable.

         Section 5.05 Successors and Assigns. This Amendment is binding upon and
shall  inure to the  benefit  of  Lender  and  Borrowers  and  their  respective
successors and assigns.

         Section 5.06  Counterparts.  This  Amendment  may be executed in one or
more  counterparts,  each of which  when so  executed  shall be  deemed to be an
original, but all of which when taken together shall constitute one and the same
instrument.

         IN WITNESS  WHEREOF,  the parties have executed  this  Amendment on the
date first above written.

                                            HELLER FINANCIAL, INC.,
                                            as Lender

                                            By:____________________________

                                            Title:__________________________


                                            MEDTOX SCIENTIFIC, INC.,
                                            (f/k/a EDITEK, Inc..), as a Borrower

                                            By:_____________________________

                                            Title:___________________________




                    [Signatures continue on following page.]


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                                        MEDTOX LABORATORIES, INC.,
                                   (f/k/a Psychiatric Diagnostic Laboratories
                                      of America, Inc.), as a Borrower

                                            By:______________________________

                                            Title:____________________________


                                         MEDTOX DIAGNOSTICS, INC.,
                                      (f/k/a Diagnostix, Inc.), as a Borrower

                                            By:_______________________________

                                            Title:_____________________________