URISPAS®
Pharmascience
Flavoxate HCl
Urinary Tract Antispasmodic
Action And Clinical Pharmacology: Flavoxate is a papaverine-like smooth muscle relaxant. It exhibits, however, greater antispasmodic activity and is less toxic.
The basic action of flavoxate is the relaxation of smooth muscle fibres of the urinary tract through a mechanism not yet defined.
By counteracting smooth muscle spasms of the urinary tract, it relieves the pain and discomfort accompanying a variety of urological disorders, e.g., frequency, dysuria, urgency, nocturia and incontinence.
In addition, flavoxate has been shown to have analgesic and local anesthetic properties in laboratory animals (mouse).
Its pharmacological effects are considered to be due to a direct action on the smooth muscle of the urinary tract, rather than to indirect blocking of autonomic nervous system receptors, as elicited by anticholinergic medications. Inhibition of phosphodiesterase by the drug itself or a metabolite is regarded to codetermine its mechanism of action.
At therapeutic concentrations, flavoxate displays low protein affinity. Its major metabolites, 3-methyl-flavone-8-carboxylic acid (MFCA) is, however, almost completely protein bound (99.5%) under comparable experimental conditions.
Absorption, distribution and excretion were determined in rats and dogs following oral and i.v. administration of C4labeled flavoxate. The drug was found to be well absorbed from the gastrointestinal tract and rapidly metabolized. Oral administration produced peak blood levels within 20 minutes. Tissue distribution was low in the brain, but high in the liver, kidneys and bladder. Urinary and fecal excretion was practically complete within 24 hours, about 30 to 40% of C4appearing in the urine and 50 to 60% concentrated in the feces. 3-Methyl-flavone-8-carboxylic acid was identified as the principal metabolite.
When administered i.v., peak blood levels were reached after 5 minutes (0.6 to 1.2 g/mL) while those of the principal metabolite (1.9 to 4.0 g/mL) were reached in 10 to 15 minutes. Appreciable amounts of the drug and its metabolite appeared in the urine within the first hour, but maximum excretion occurred between 2 and 3 hours. Collections made during 24 hours did not contain any free drug but had high concentrations of 3-methyl-flavone-8-carboxylic acid either free or as conjugated glucuronide. The experimental data confirmed earlier observations that the drug does not accumulate in the body.
Kohler and Morales observed that in rats, peak plasma levels were reached approximately 2 hours after oral or intraperitoneal administration, and that rabbits excreted about 76% of the administered dose (100 mg/kg) over a 24 hour period.
It is not indicated for the definitive treatment of urinary tract infections, but is compatible with drugs used for their management. Where evidence of such infection is present, appropriate anti-infective therapy should be instituted concomitantly. In non-infectious cases of bladder inflammation or irritation, flavoxate alone can provide symptomatic relief.
Flavoxate is also indicated for the relief of vesicourethral spasms due to catheterization, cystoscopy or indwelling catheters, prior to cystoscopy or catheterization, and sequelae of surgical intervention of the lower urinary tract.
Indications And Clinical Uses: The symptomatic relief of dysuria, urgency, nocturia, suprapubic pain, frequency and incontinence, as may occur in cystitis, prostatitis, urethritis, urethrocystitis and urethrotrigonitis.
Flavoxate is also indicated for the relief of vesicourethral spasms due to catheterization, cystoscopy or indwelling catheters, prior to cystoscopy or catheterization, and sequelae of surgical intervention of the lower urinary tract.
Contra-Indications: Pyloric or duodenal obstruction, obstructive intestinal lesions or ileus, achalasia, gastrointestinal hemorrhage and obstructive uropathies of the lower urinary tract. It is not yet recommended for infants and children under 12 years of age since safety and efficacy studies in this age group are not completed.
Manufacturers’ Warnings In Clinical States: Flavoxate should be given cautiously to patients with suspected glaucoma.
Pregnancy: Although studies in sensitive animals have not shown any potential for teratogenic effects, the drug should only be used during pregnancy if, in the opinion of the physician, the anticipated benefits outweigh any risks.
Precautions: Occupational Hazards: In the event of drowsiness or blurred vision, the patient should not operate a motor vehicle or any machinery, and refrain from participating in activities requiring alertness.
Adverse Reactions: Adverse reactions reported include nausea and vomiting, dry mouth, nervousness, vertigo, headache, drowsiness, blurred vision, increased ocular tension, disturbance in eye accommodation, urticaria and other dermatoses, mental confusion, especially in the elderly patient, dysuria, tachycardia and palpitation, hyperpyrexia, eosinophilia and leukopenia (one case which was reversible upon discontinuation of the drug).
Symptoms And Treatment Of Overdose: Symptoms: Although no such experience has been reported to-date, it is considered likely that the following symptoms may be observed: nausea, vomiting, dryness of the mouth, blurred vision, disturbance in visual accommodation, tachycardia, tachypnea, mental confusion, excitement, convulsions, respiratory failure and coma.
Treatment: There is no known specific antidote. Treatment is, essentially, symptomatic with close monitoring of vital functions imperative.
In a conscious, alert patient prompt evacuation of the stomach should be performed. When evacuation is complete, observation and further treatment should be made according to the attending physician’s assessment of the patient.
If overdosage is extreme, or there is delay in removing the drug from the stomach, administration of a parasympathomimetic drug should be considered.
In the presence of severe anticholinergic reactions, slow i.v. injection of 1 to 4 mg of physostigmine is indicated, and in case of favorable response, repeated doses may be administered. If marked excitement is observed, diazepam may be given for sedation and control of convulsions. In a comatosed patient, a clear airway must be established immediately and artificial respiration instituted.
Dosage And Administration: Adults and children over 12 years of age: 1 tablet 3 or 4 times a day.
Flavoxate is rapidly absorbed. Clinical response will vary depending on the nature and severity of symptoms diagnosed and the patient’s overall condition. Therapeutic effects on bladder musculature may be observed within 2 or 3 hours.
In patients with infection, treatment is usually continued for as long as antibacterial or anti-infective medications are administered (i.e., a week or so). In patients with chronic bladder symptoms, maintenance therapy for prolonged periods may be required for optimum results. With improvement of symptoms, the dose may be reduced.
It is recommended that tablets be taken after meals.
Availability And Storage: Each white, sugar coated tablet contains: flavoxate HCl 200 mg. Bottles of 100.
URISPAS® Pharmascience Flavoxate HCl Urinary Tract Antispasmodic
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