Usage
- Flavoxate is prescribed for the symptomatic relief of urinary tract spasms, dysuria, urgency, nocturia, suprapubic pain, frequency, and incontinence associated with conditions like cystitis, prostatitis, urethritis, urethrocystitis, and urethrotrigonitis. It is also used to relieve bladder spasms caused by catheterization, cystoscopy, or indwelling catheters.
- Pharmacological classification: Urinary antispasmodic, antimuscarinic.
- Mechanism of action: Flavoxate is a smooth muscle relaxant that acts directly on the smooth muscle of the urinary tract. It inhibits bladder contractions, increases bladder capacity, reduces the frequency of micturition, and decreases micturition pressure.
Alternate Names
- Generic Name: Flavoxate hydrochloride.
- Brand Name: Urispas.
How It Works
- Pharmacodynamics: Flavoxate and its primary metabolite, 3-methylflavone-8-carboxylic acid (MFCA), exhibit direct antispasmodic activity on urinary tract smooth muscle. This involves intracellular cyclic AMP accumulation and calcium channel blocking, leading to relaxation of the detrusor muscle. It also possesses some local anesthetic and analgesic properties.
- Pharmacokinetics: Flavoxate is rapidly absorbed after oral administration and extensively metabolized to MFCA. Peak plasma concentrations of MFCA are reached within 30-60 minutes after a 200 mg dose. The drug is primarily excreted in the urine as MFCA, with approximately 50% of the dose eliminated within 12 hours.
- Mode of Action: Flavoxate exerts its effects by directly relaxing the smooth muscle of the urinary tract, primarily the detrusor muscle of the bladder. Its mechanism involves inhibiting the influx of calcium ions into smooth muscle cells, thereby reducing muscle contractility and spasm.
- Elimination Pathways: Flavoxate is metabolized in the liver to 3-methylflavone-8-carboxylic acid (MFCA), which is the primary active metabolite. Both the parent drug and its metabolite are excreted mainly in the urine, with a smaller portion eliminated in the feces.
Dosage
Standard Dosage
Adults:
- 100-200 mg orally three to four times daily.
- The dose may be reduced as symptoms improve.
Children:
- 12 years and older: Same as adult dose.
- Safety and efficacy have not been established in children younger than 12 years.
Special Cases:
- Elderly Patients: Dose adjustment is usually not required but should be approached cautiously in elderly patients, especially those with renal or hepatic impairment. Start at the lower end of the dosage range.
- Patients with Renal Impairment: Exercise caution and consider a reduced dose as flavoxate’s metabolite is primarily renally excreted.
- Patients with Hepatic Dysfunction: Exercise caution and initiate at lower dosage range due to potential changes in metabolism.
- Patients with Comorbid Conditions: Use with caution in patients with glaucoma, gastrointestinal obstructive disorders, or myasthenia gravis.
Clinical Use Cases
- Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use, Emergency Situations: While Flavoxate itself isn’t indicated for these situations, it can be utilized to manage bladder spasms that might arise secondary to these procedures or conditions. Dosages would generally align with the standard recommendations.
Dosage Adjustments
- Dosage adjustments may be necessary in elderly individuals, those with hepatic or renal impairment, and patients with other comorbid conditions. The dose should be titrated to the individual’s needs and response.
Side Effects
Common Side Effects
- Nausea, vomiting, dry mouth, dyspepsia, blurred vision, dizziness, drowsiness, headache, nervousness.
Rare but Serious Side Effects
- Allergic reactions (e.g., skin rash, itching, hives, difficulty breathing, swelling), eye pain, severe dizziness or lightheadedness, confusion, hallucinations, fast/irregular heartbeat.
Long-Term Effects
- Long-term use might be associated with anticholinergic effects such as constipation, urinary retention, or cognitive impairment, especially in the elderly.
Adverse Drug Reactions (ADR)
- Severe allergic reactions, angioedema, anaphylaxis, acute glaucoma.
Contraindications
- Pyloric or duodenal obstruction, ileus, achalasia, gastrointestinal hemorrhage, obstructive uropathies, urinary retention, glaucoma, myasthenia gravis.
Drug Interactions
- Other anticholinergic medications (additive effects), pramlintide, secretin.
- May interact with certain medications such as antibiotics, anticoagulants, antihypertensives.
- Alcohol, smoking, and grapefruit juice may interact with flavoxate.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: B (Animal studies have not shown any adverse effects, but controlled studies in pregnant women are lacking. )
- Flavoxate should be used during pregnancy only if clearly needed.
- It is unknown if flavoxate passes into breast milk. Consult a physician before breastfeeding while using flavoxate.
Drug Profile Summary
- Mechanism of Action: Relaxes smooth muscle in the urinary tract.
- Side Effects: Nausea, dry mouth, blurred vision, dizziness, drowsiness.
- Contraindications: Obstructive GI disorders, urinary retention, glaucoma.
- Drug Interactions: Other anticholinergic drugs.
- Pregnancy & Breastfeeding: Category B; use with caution.
- Dosage: 100-200 mg TID or QID.
- Monitoring Parameters: Urinary frequency, urgency, and side effects.
Popular Combinations
- Flavoxate is sometimes used in combination with antibiotics for urinary tract infections, or with alpha-blockers like tamsulosin for benign prostatic hyperplasia with associated bladder symptoms.
Precautions
- General Precautions: Screen for underlying medical conditions that may contraindicate its use.
- Specific Populations: Use cautiously in the elderly and those with renal/hepatic impairment. Safety in children under 12 has not been established. Use during pregnancy and breastfeeding only if clearly needed.
- Lifestyle Considerations: Flavoxate may cause drowsiness or blurred vision. Advise patients against operating machinery or driving.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Flavoxate?
A: Adults and children 12 years and older: 100-200 mg orally three to four times a day. The dose may be reduced as symptoms improve. Children younger than 12: Safety and efficacy not established.
Q2: What are the common side effects of Flavoxate?
A: Nausea, dry mouth, blurred vision, dizziness, drowsiness, headache.
Q3: What are the contraindications for using Flavoxate?
A: Gastrointestinal obstruction, urinary retention, glaucoma, myasthenia gravis.
Q4: How does Flavoxate work?
A: Flavoxate is an antispasmodic that relaxes the smooth muscle in the urinary tract.
Q5: Can Flavoxate be used during pregnancy?
A: Flavoxate is a Pregnancy Category B drug. It should be used during pregnancy only if clearly needed and under the guidance of a physician.
Q6: Does Flavoxate interact with other medications?
A: Yes, Flavoxate can interact with other anticholinergic drugs, potentially leading to increased side effects. It may also interact with pramlintide and secretin. Consult a doctor or pharmacist before taking Flavoxate with other medications.
Q7: Can Flavoxate be used to treat urinary tract infections (UTIs)?
A: Flavoxate does not treat the infection itself; it relieves the painful spasms and discomfort associated with UTIs. Antibiotics are required to treat the underlying infection.
Q8: What should patients be advised regarding activities while taking Flavoxate?
A: Patients should be advised to avoid driving or operating machinery as Flavoxate can cause drowsiness or blurred vision.
Q9: Are there any long-term effects associated with Flavoxate use?
A: Long-term use, particularly in the elderly, may be associated with anticholinergic effects like constipation, urinary retention, and cognitive impairment. Regular monitoring is recommended.
Q10: How should Flavoxate be stored?
A: Store at room temperature away from moisture, heat, and direct light.
