Exenatide

peptide · endocrine · digestive · Subcutaneous

Exenatide, a peptide. Synthetic exendin-4 — 39-residue peptide from Heloderma suspectum (Gila monster) saliva with ~53% homology to… Subcutaneous half-life 2.4 h.

Synthetic exendin-4 — 39-residue peptide from Heloderma suspectum (Gila monster) saliva with ~53% homology to mammalian GLP-1. Resists DPP-4 cleavage (Gly at position 2) giving a 2–3 h plasma t½ (vs GLP-1's 1.5 min). Activates GLP-1R → glucose-dependent insulin secretion, glucagon suppression, slowed gastric emptying, central satiety. LAR microspheres release drug over weeks; takes 6–10 weeks to reach steady state.

PK describes the twice-daily IMMEDIATE-RELEASE product, not the weekly formulation. Bray 2006 (PMID:16484515), verbatim "The mean apparent volume of distribution after administration of a single subcutaneous dose is 28.3 L" and "The terminal half-life of the drug is 2.4 hours". F is pinned to 1 because that volume is explicitly apparent. The previous citation (PMID:28085521) is a review whose abstract carries no numbers and covers both formulations. F 0.7 dropped: its only source says "Based on animal studies ... between 65% and 75%" without naming a species, so it cannot be labelled under the species policy, and 0.7 was a range midpoint besides. ka 0.3 /h dropped — no source, and inconsistent with the 2.1 h time to peak. Note Zhao 2008 (PMID:18793576) measured a materially lower 0.99-1.25 h and 19.2-22.3 L in 24 volunteers; not averaged.

Pharmacokinetics

Sources: PMID:28085521, PMID:7851494, PMID:16484515, PMID:18793576