Dicyclomine
Dicyclomine. Antimuscarinic + direct GI smooth muscle relaxant — used for IBS-associated cramping pain. Anticholinergic burden — Beers-list problematic in elderly. PK…
Antimuscarinic + direct GI smooth muscle relaxant — used for IBS-associated cramping pain. Anticholinergic burden — Beers-list problematic in elderly. PK (Bentyl label): Relative F 67% (oral vs IM), apparent Vd 3.65 L/kg (~256 L), t½ 1.8 h, Tmax 1–1.5 h (capsule/tablet/solution equivalent). Note: the t½ correction here resolves a v0.x-era authored value of 4 h that did not match the Bentyl label. Anticholinergic with central muscarinic effects at therapeutic doses.
PK REMOVED. THE INSERT ITSELF DISOWNS THE ONE HALF-LIFE IT QUANTIFIES: "approximately 1.8 hours when plasma concentrations were measured FOR 9 HOURS ... In subsequent studies, plasma concentrations were followed for up to 24 hours after a single dose, showing a SECONDARY PHASE OF ELIMINATION WITH A SOMEWHAT LONGER HALF-LIFE". That truncated first phase was stored beside a large volume, and the pair implies a clearance of 1.64 litres per minute — ABOVE HEPATIC BLOOD FLOW, and roughly twenty times filtration for a drug the same label says is principally renally excreted. The volume is also explicitly ORAL-derived, "Mean volume of distribution for a 20 mg ORAL DOSE is approximately 3.65 L/kg", so pairing it with a bioavailability divided by that quantity twice. AND THAT BIOAVAILABILITY IS ABSENT FROM EVERY FDA LABEL FETCHED: the insert says "Intramuscular injection is about TWICE as bioavailable as oral dosage forms", corroborated by its own dosing section, which is a RELATIVE two-to-one ratio rather than the stored figure — so the record source_label attributed to the FDA label a number the label does not contain. Every indexed paper is an assay method without an abstract, a rodent interaction study, or a rabbit formulation study.