Documentation
Common Data Model (CDM)
Convert Database to CDM (ETL)
Tool Specific Documentation
Common Data Model (CDM)
Convert Database to CDM (ETL)
Tool Specific Documentation
Proposal for conventions to achieve consistent entries in the attribute quantity of the DRUG_EXPOSURE table and entries in the DRUG_STRENGTH table. Eventually, we will be able to calculate the total amount of the active ingredient by
DRUG_EXPOSURE.quantity x DRUG_STRENGTH.numerator_value [numerator_unit_concept_id]
(for concentrations) or DRUG_EXPOSURE.quantity x DRUG_STRENGTH.amount_value [amount_unit_concept_id]
(for pieces, e.g. tablets)For drugs with a dose release over time (e.g. Patches) we will be able to calculate the hourly rate by
DRUG_STRENGTH.numerator_value [numerator_unit_concept_id]
Probably, nothing has to be changed. But we should crosscheck the following assumed properties of the DRUG_STRENGTH table coming from RxNorm and apply these for future enhancements:
With the above mentioned conventions the fields effective_drug_dose and dose_unit_concept_id can be removed. They don’t support multiple ingredients anyway.
In order to support quantified drugs we need an additional field denominator_value. For compounding we would need to add records to DRUG_STRENGTH for all compounds (drug_concept_id=ingredient_concept_id) with the mg concept in the denominator_unit_concept_id for all "dry" compounds and mL for the "wet" ones. We could steal the knowledge what is what from RxNorm.
1  Solid preparations, preparations where dose cannot be split 

Example: 20 tablets of 19020053 “Acetaminophen 500 MG Oral Tablet”  
DRUG_STRENGTH  The denominator_unit is empty. Amount_value and amount_unit_concept_id contain the effective dose. Note that in nonUS databases the quantity could be retrieved from the box_size field, however, the ETL should copy that to the DRUG_EXPOSURE.quantity field. 
DRUG_EXPOSURE  Quantity refers to number of pieces, e.g. 20 tablets 
Total dose=  quantity x amount_value [amount_unit_concept_id] 
Acetaminophen dose = 20 x 500 mg = 10,000 mg 

2  Puffs of an inhaler 
Example: 150 puffs of 21174430 “Nicotine 0.5 MG/ACTUAT [Nicorette]”. Note: There is no difference to use case 1 besides that the DRUG_STRENGTH table has {actuat} in the denominator_unit. In this case the strength is provided in the numerator.  
DRUG_STRENGTH  The denominator_unit is {actuat}. The numerator value and numerator unit contain the dose per actuation (puff) 
DRUG_EXPOSURE  Quantity refers to the number puffs, e.g. 150 
Total dose=  quantity x numerator_value [numerator_unit_concept_id] 
Nicotin dose = 150 x 0.5 mg = 75 mg 

3  Quantified Drugs 
Example: 43275770 “60 ML Acetaminophen 50 MG/ML Oral Solution”, meaning, there are 60 mL of Acetaminophe (Paracetamol) of a concentration of 50 mg/mL. Two such bottles are prescribed.  
DRUG_STRENGTH  The concentration is given in the numerator/denominator fields, with the denominator unit either mg or mL, and the denominator value typically not 1. E.g. 3000 mg in 60 mL. 
DRUG_EXPOSURE  Quantity refers to a fraction or multiple of the container. E.g. 2 
Total dose=  quantity x numerator_value [numerator_unit_concept_id] 
Acetaminophen dose = 2 x 3000 mg = 6000 mg 

4  Liquid drugs, or drugs where the amount can be split randomly. The total amount in given in quantity 
Example: 42799258 “Benzyl Alcohol 0.1 ML/ML / Pramoxine hydrochloride 0.01 MG/MG Topical Gel” dispensed in a 1.25 oz pack.  
DRUG_STRENGTH  The concentration is given in the numerator/denominator fields, with the denominator unit either mg or mL, and the denominator value as null. E.g. Benzyl Alcohol in mL and Pramoxine hydrochloride in mg 
DRUG_EXPOSURE  Quantity refers to the unit provided in DRUG_STRENGTH. Since both mL and mg are found mg is preferred. E.g. 1.25 x 30 (conversion factor oz → mL) x 1000 (conversion mL → mg) = 37,000 
Total dose=  quantity x numerator_value [numerator_unit_concept_id] 
Benzyl Alcohol dose = 37,000 x 0.1 mL x 0.001 = 3.7 mL 

Pramoxine hydrochloride dose = 37,000 x 0.01 mg = 370 mg 

Note: At analysis time, the denominator should be checked in the DRUG_STRENGTH table. As mg is used for the second ingredient the factor 1000 should be applied to convert between g and mg.  
5  Compounded drugs 
Example: 30 mL Ibuprofen 20% / Piroxicam 1% Cream.  
DRUG_STRENGTH  Two separate entries for the ingredients of Ibuprofen and Piroxicam are required, with an amount value of null and a amount unit of mg. 
DRUG_EXPOSURE  Quantity refers to the total weight amount of the compounded ingredient. Use one record in the DRUG_EXPOSURE table for each compound. Eg.g 20% Ibuprofen in 30 mL = 6 mL, 1% Piroxicam in 30 mL = 0.3 mL 
Total dose=  Depends on the drugs involved: One of the use cases above. 
Ibuprofen dose = 6 x 1000 = 6000 mg 

Piroxicam dose = 0.3 x 1000 = 300 mg 

Note: At analysis time, the denominator should be checked for both ingredients in the DRUG_STRENGTH table. If it is not mg a conversion factor of 1000 should be applied to convert between mL/g and mg.  
6  Drugs with delayed release over time, e.g. Patches 
Example: 1518199 “Ethinyl Estradiol 0.000833 MG/HR / norelgestromin 0.00625 MG/HR Weekly Transdermal Patch  
DRUG_STRENGTH  The release is provided as numerator/denominator pair, with the denominator value as null and the denominator unit hour. E.g. Ethinyl Estradiol 0.000833 mg/h / norelgestromin 0.00625 mg/h 
DRUG_EXPOSURE  Quantity refers to the number of pieces. E.g. 1 patch. 
Release rate=  numerator_value [numerator_unit_concept_id] 
Ethinyl Estradiol rate = 0.000833 mg/h 

norelgestromin rate 0.00625 mg/h 

Note: This can be converted to a daily dosage by multiplying it with 24. (Assuming 1 patch at a time for at least 24 hours) 