Drug Interaction
An alteration in one drug's effect caused by another drug, food, or substance. Peptide drugs have a generally favourable interaction profile because they are not metabolised by cytochrome P450 enzymes. However, GLP-1 receptor agonists can delay absorption of oral medications by slowing gastric emptying.
Technical Context
Peptide drug interaction profile is generally favourable because: peptides are not metabolised by hepatic CYP450 enzymes (the major source of small molecule drug interactions), they do not induce or inhibit CYP isoforms, and they are not substrates for P-glycoprotein or other drug transporters. However, clinically relevant interactions exist: GLP-1 RA gastric emptying delay can slow absorption of concurrently administered oral drugs — particularly relevant for drugs with narrow therapeutic windows (warfarin, levothyroxine, oral contraceptives) or time-sensitive absorption (antibiotics). For oral semaglutide, the fasting requirement (30 min before food/other medications) manages this interaction. GnRH compounds interact pharmacodynamically with sex hormone-dependent therapies. Somatostatin analogues can alter insulin and glucagon secretion, requiring diabetes medication dose adjustment. Drug interaction studies are a standard component of peptide clinical development programmes.