When an outpatient provider writes a prescription, the strength of the tablet (capsule, etc) will be specified. For example, the prescription will read, "Prednisone 20 mg tablet; Take 2 tablets by mouth every day". This is a prescription for 40 mg of prednisone daily.
For inpatient providers, the strength of the tablet (etc) is typically not specified. They only want to specify the total amount of drug. For example, "40 mg of prednisone by mouth daily".
RxNorm is the vocabulary that is used for medications. It has various different types of term. The "SCD" term type refers to "Semantic clinical drugs". This is the type that specifies the specific type of drug tablet (etc). For example, "Prednisone 20 mg tablet" has the RxNorm code "312615". As mentioned above, the SCD term type is not as useful for inpatient medication orders. What type would be useful? When originally examining RxNorm, the "Semantic Clinical Drug Form" (SCDF) seemed to be what I wanted. It was essentially like the SCD terms, but without the specific strength. For example, the SCDF code for "prednisone tablet" is "373585".
The Issues:
For one, the SCDF is actually a combination of REGULAR ingredients (IN) + the dose form. By stressing "regular", I mean to point out that this does not use the "precise ingredients" (PIN). (Quick example of regular ingredient vs precise ingredient : "metoprolol" is a regular ingredient, "metoprolol succinate" is a precise ingredient). This will work for most medications, but when you have medications where the precise ingredient matters, you may find that the SCDF is inadequate if those precise ingredients use the same dose form.
Example--the SCDF for "Penicillin G injectable suspension" includes the following different medications:
* Penicillin G procaine
* Penicillin G benzathine
* Penicillin G procaine + penicillin G benzathine combo
Another issue is that injections don't really fit the expected behavior. Normal saline and hypertonic saline share the same SCDF, despite being dramatically different in their indications.
