Solifenacin

Absorption

Solifenacin is well absorbed in the duodenum, jejunum, and ileum but not the stomach. Absorption occurs via passive diffusion and so no transporters are involved. The mean oral bioavailability of solifenacin is 88%. The Tmax of solifenacin is 3-8 hours with a Css of 32.3ng/mL for a 5mg oral dose and 62.9ng/mL for a 10mg oral dose.

Toxicity

The LD50 of Solifenacin has yet to be determined.
Signs of overdose include severe anticholinergic effects, mental status changes, and decreased consciousness. In case of overdose, treat patients with gastric lavage and supportive measures. Monitor patients with an ECG.

The Uses of Solifenacin

muscarinic M3 antagonist

Indications

Solifenacin tablets are indicated to treat an overactive bladder with urinary incontinence, urgency, and frequency.

Background

Solifenacin is a competitive muscarinic receptor antagonist indicated to treat an overactive bladder with urinary incontinence, urgency, and frequency. It has a long duration of action as it is usually taken once daily.
Solifenacin was granted FDA approval on 19 November 2004.

Definition

ChEBI: Solifenacin is a member of isoquinolines.

brand name

Vesicare (Astellas).

Pharmacokinetics

Solifenacin antagonizes the M2 and M3 muscarinic receptors in the bladder to treat an overactive bladder. It has a long duration of action as it is usually taken once daily. Patients taking solifenacin should be aware of the risks of angioedema and anaphylaxis.

Metabolism

Solifenacin undergoes N-oxidation at the quinuclidin ring by cytochrome P450, though the exact enzymes are not revealed in the literature. The tetrahydroisoquinolone ring is 4R-hydroxylated by CYP3A4, CYP1A1, and CYP2D6. A 4R-hydroxy N-oxide metabolite is also formed by CYP3A4. Finally, solifenacin can undergo direct glucuronidation. Only solifenacin and the 4R-hydroxy metabolite are pharmacologically active.