Add Chemical structure (CS) to criteria when filtering for Drug Class

[xixilili]

Only pharmacologic classes corresponding to the "Chemical/Ingredient," "Mechanism of Action," and "Physiologic Effect" FDA class types were included in Hetionet to avoid pharmacologic classes that were synonymous with indications.

According to the FDA class types, a pharmacologic class is a group of drugs that share scientifically documented properties. Specifically, for purposes of this guidance, pharmacologic class is defined on the basis of any one of the following three attributes of the drug:

1. Mechanism of action (MOA) — Pharmacologic action at the receptor, membrane, or tissue level
2. Physiologic effect (PE) — Pharmacologic effect at the organ, system, or whole body level
3. Chemical structure (CS)

It seems Hetionet used "Chemical/Ingredient" instead of "Chemical structure (CS)," as CS does not exist in the version of DrugCentral data they used. Since CS is the latest version, we'll add the class "Chemical Structure (CS)" to the criteria when filtering for Drug Class.