indication

For symptomatic relief of dysuria, urgency, nocturia, suprapubic pain, frequency and incontinence as may occur in cystitis, prostatitis, urethritis, urethrocystitis/urethrotrigonitis.

pharmacology

Flavoxate is a spasmolytic flavone derivative that acts by relaxing the smooth muscle in the urinary tract. Flavoxate is a competitive muscarinic receptor antagonist indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. Muscarinic receptors play an important role in several major cholin-ergically mediated functions, including contractions of urinary bladder smooth muscle and stimulation of salivary secretion.

mechanism of action

Flavoxate acts as a direct antagonist at muscarinic acetylcholine receptors in cholinergically innervated organs. Its anticholinergic-parasympatholytic action reduces the tonus of smooth muscle in the bladder, effectively reducing the number of required voids, urge incontinence episodes, urge severity and improving retention, facilitating increased volume per void.

toxicity

The oral LD50 for flavoxate HCl in rats is 4273 mg/kg. The oral LD50 for flavoxate HCl in mice is 1837 mg/kg. Symptoms of overdose include convulsions, decreased ability to sweat, (warm, red skin, dry mouth, and increased body temperature), hallucinations, increased heart rate and blood pressure, and mental confusion.

absorption

Well absorbed from gastrointestinal tract.

route of elimination

57% of the flavoxate HCl was excreted in the urine within 24 hours.

drug interactions

Donepezil: Possible antagonism of action

Galantamine: Possible antagonism of action

Rivastigmine: Possible antagonism of action

Tacrine: The therapeutic effects of the central acetylcholinesterase inhibitor, Tacrine, and/or the anticholinergic, Flavoxate, may be reduced due to antagonism. The interaction may be beneficial when the anticholinergic action is a side effect. Monitor for decreased efficacy of both agents.

Trimethobenzamide: Trimethobenzamide and Flavoxate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Triprolidine: Triprolidine and Flavoxate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trospium: Trospium and Flavoxate, two anticholinergics, may cause additive anticholinergic effects and enhanced adverse/toxic effects. Monitor for enhanced anticholinergic effects.