Recombinant somatotropin is regulated as a biological drug product under the Public Health Service Act. Importers must be licensed or authorized by FDA, and the manufacturing facility must hold an approved Biologics License Application (BLA) or be covered under an approved drug application. Shipments not meeting these requirements are subject to refusal of admission.

Structural analogues — modified peptide sequences designed to mimic or modulate growth hormone activity — are explicitly included in heading 293711 and enter under 2937110000 alongside somatotropin itself. Classification does not change based on whether the compound is a direct copy or a modified analogue, provided the structural relationship to somatotropin is established. Novel compounds with more distant structural relationships may require a binding ruling to confirm classification.