Flavoxate
Flavoxate Hydrochloride
Also known as: Urispas · flavoxato · AK 123 · Rec 7-0040
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| To decrease urinary bladder contractility | 100-200 mg (per dog) | PO | q6-8h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Flavoxate is a urinary antispasmodic used primarily as an alternative treatment for detrusor hyperspasticity (hyperactive bladder or urge incontinence) in dogs.
- It is particularly useful in refractory cases where standard therapies like phenylpropanolamine (PPA) alone have failed to achieve continence.
-
Clinical Pearl: While not commonly used in veterinary medicine due to limited pharmacokinetic data, its dual action as a smooth muscle relaxant and antimuscarinic makes it a valuable second-line or adjunctive agent for urge incontinence.
Mechanism of action
Flavoxate exerts its effects through two primary mechanisms:
- Direct Smooth Muscle Relaxation: It acts directly on the smooth muscle of the urinary tract, reducing spasms and increasing bladder capacity.
- Antimuscarinic Activity: It competitively antagonizes muscarinic acetylcholine receptors in the detrusor muscle → inhibits parasympathetic nerve impulses → reduces involuntary bladder contractions.
Unlike pure anticholinergics, its direct musculotropic effect provides targeted relief of urinary tract spasms.
Safety & warnings
Contraindications
- Pyloric or duodenal obstruction
- Obstructive intestinal lesions or ileus
- Achalasia
- Gastrointestinal hemorrhage
- Obstructive uropathies of the lower urinary tract
Adverse effects
- Weakness
- Gastrointestinal upset
- Changes in activity level
Precautions
Use with caution in patients with suspected glaucoma.
Reproductive/Nursing Safety:
- FDA Category B in humans (animal studies show no fetal risk, but adequate human studies are lacking).
- It is unknown if the drug is excreted in milk; use with caution in nursing mothers.
Drug interactions
Concomitant use may cause additive anticholinergic effects.
Monitoring
- Clinical efficacy (improvement in continence)
- Adverse effects (especially weakness and GI signs)
- Occasional CBCs (to monitor for neutropenia if used chronically)
- Creatinine (to monitor for renal dysfunction if used chronically)
Pharmacokinetics
Absorption
In humans, onset of action is within an hour.
Distribution
In humans, peak effects occur at around 2 hours post dose.
Metabolism
No specific information located for dogs or cats.
Elimination
In humans, 57% of a dose is excreted in the urine within 24 hours.
Overdose
The approximate oral LD-50 for rats and mice are 4300 mg/kg and 1800 mg/kg respectively. While it has a wide margin of safety, massive overdose would likely result in severe anticholinergic signs (e.g., dry mouth, tachycardia, urinary retention, GI stasis). Treatment should be supportive and symptomatic.
Available products
Formulations
- Oral tablets
Human-labeled
- Flavoxate HCl Oral Tablets (film-coated) 100 mg: Urispas® (Ortho-McNeil), generic
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Flavoxate tablets should be stored at room temperature (15-30°C).
Client information
Purpose: Flavoxate is prescribed to help control urinary incontinence (leaking urine) or an overactive bladder in your dog, especially when other standard medications haven't fully worked.
What to Watch For: The most common side effect is weakness or a noticeable decrease in your dog's activity level. Mild stomach upset may also occur.
Important: If your dog becomes excessively weak, lethargic, or stops eating, contact your veterinarian.
Administration: Give exactly as prescribed. Do not stop the medication abruptly without consulting your vet.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.