Biochemistry is considered the mother of all biological sciences.

Importance of biochemistry in Pharmacy:

Drug Constitution: Biochemistry gives an idea of the constitution of the drug, its chances of degradation with varying temperature, etc. It also gives an idea of how modifying the chemistry of the drug will improve the drug efficiency, minimize its side effects, etc.

Drug storage: The storage condition required can be estimated by the biochemical test. For example many enzymes, hormones are stored for dispensing. These get deteriorated over time due to temperature or oxidation, contamination and also due to improper storage.
Drug metabolism: It also gives an idea of how drug molecules are metabolized by many biochemical reactions in the presence of enzymes. This helps to avoid drugs which have a poor metabolism or those with excessive side effects from being prescribed or dispensed to the patient.
Biochemical tests: These tests help fix the specific half-life or date of expiry of drugs.