rxnorm/NDC_Normalization_Code.md

Routine to transform given NDC code (v_ndc) to HIPAA 11-digit format (ret_ndc)

Define variables

• v_ndc = value of source NDC to be normalized
• v_rsab = RxNorm root source abbreviation (SAB)
• ret_ndc = string(50); 'the normalized NDC
• v_format = string(50); 'the format of source NDC code

Find the format of source NDC value to be normalized

Format can vary from source to source

	IF LEN(v_ndc) - LEN(REPLACE (v_ndc, '-')) = 2  ## If NDC string contains 2 dashes
	THEN              ## find the format of the NDC string.  Format could be 6-4-2, 6-4-1, 5-4-2, etc.
		v_format =
			LEN (SUBSTR (v_ndc, 1, INSTR (v_ndc, '-') - 1))  ##  find number of digits before first dash
			+ '-'
			+ LEN (SUBSTR (v_ndc,
					   INSTR (v_ndc, '-') + 1,     ## digit number after first dash
					   INSTR (v_ndc, '-', 1, 2) - INSTR (v_ndc, '-')  -1       ## number of digits between first and second dash
					   )
					)  ## find number of digits between the dashes
			+ '-'
			+ LEN (SUBSTR (v_ndc, INSTR (v_ndc, '-', 1, 2) + 1))  ## number of digits after second dash
	END IF  ##  v_format now contains ‘X-X-X’

Format has been identified. Convert into normalized NDC

    IF v_format IS NOT NULL      ##  source NDC string contains dashes
    THEN
        IF v_format = '6-4-2'   ## drop first digit of string
        THEN
            ret_ndc =
               SUBSTR (v_ndc, 2, 5)  ## last 5 digits of number before first dash
             + SUBSTR (v_ndc, 8, 4)   ## all four digits after first dash
             + SUBSTR (v_ndc, 13, 2)  ##  last 2 digits after second dash
        ELSE IF v_format = '6-4-1'              ## drop first digit of string
        THEN
            ret_ndc =
                SUBSTR (v_ndc, 2, 5)
            + SUBSTR (v_ndc, 8, 4)
            + '0'                   ## pad last digit to 2 chars
            + SUBSTR (v_ndc, 13, 1)
        ELSE IF v_format = '6-3-2'              ## drop first digit of string
        THEN
            ret_ndc =
                SUBSTR (v_ndc, 2, 5)
            + '0'                    ## pad second digit to 4 chars
            + SUBSTR (v_ndc, 8, 3)
            + SUBSTR (v_ndc, 12, 2)
        ELSE IF v_format = '6-3-1'             ## drop first digit of string
        THEN
            ret_ndc =
                SUBSTR (v_ndc, 2, 5)
            + '0'               ## pad second digit to 4 chars
            + SUBSTR (v_ndc, 8, 3)
            + '0'              ## pad third digit to 2 chars
            + SUBSTR (v_ndc, 12, 1)
        ELSE IF v_format = '5-4-2'             ## keep all digits
        THEN
            ret_ndc =
                SUBSTR (v_ndc, 1, 5)
            + SUBSTR (v_ndc, 7, 4)
            + SUBSTR (v_ndc, 12, 2)
        ELSE IF v_format = '5-4-1'             ## keep all digits
        THEN
            ret_ndc =
                SUBSTR (v_ndc, 1, 5)
            + SUBSTR (v_ndc, 7, 4)
            + '0'                 ## pad third digit to 2 chars
            + SUBSTR (v_ndc, 12, 1)
        ELSE IF v_format = '5-3-2'           ## keep all digits
        THEN
            ret_ndc =
                SUBSTR (v_ndc, 1, 5)
            + '0'              ##  pad second digit to 4 chars
            + SUBSTR (v_ndc, 7, 3)
            + SUBSTR (v_ndc, 11, 2)
        ELSE IF v_format = '4-4-2'  ## keep all digits
        THEN
            ret_ndc =
                '0'                 ## pad first digit to 5 chars
            + SUBSTR (v_ndc, 1, 4)
            + SUBSTR (v_ndc, 6, 4)
            + SUBSTR (v_ndc, 11, 2)
        END IF

If NDC passed has 11 digits without any '-' then return input NDC as Normalized NDC value

NDC string is already in normalized format, it does not contain any dashes

        ELSE IF INSTR (v_ndc, '-') = 0 AND LEN (v_ndc) = 11
        THEN
            ret_ndc = v_ndc

If NDC passed has 12 digits and first char is '0' and its from VANDF then trim first char

VA sometimes pads '0' to make it 12 digit NDC

        ELSE IF INSTR (v_ndc, '-') = 0    ## no dashes in string
               AND LEN (v_ndc) = 12
            	 AND SUBSTR (v_ndc, 1, 1) = '0'    ## first digit is 0
            	 AND v_rsab = 'VANDF'
        THEN
            ret_ndc = SUBSTR (v_ndc, 2)   ## return all digits except first char which is 0
        END IF

Replace '*' with '0' as some of the NDCs from MTHFDA contain * instead of 0

     ret_ndc = REPLACE (ret_ndc, '\*', '0')

Check to see if NDC value contains any Alphanumeric values, if yes, then its an invalid NDC code

     IF TRIM (TRANSLATE (ret_ndc, '1234567890', ' ')) IS NOT NULL
     THEN
        ret_ndc = ''
     END IF
     RETURN ret_ndc

For any other cases, return NULL. String cannot be normalized