Fesoterodine

When should one not use Fesoterodine

• If you are allergic to fesoterodine, peanuts, or any of the other ingredients of this medicine.
• If you are unable to pass urine normally or have urinary retention.
• If you have a condition in which the stomach empties very slowly or food remains in the stomach for too long (gastric retention).
• If you have uncontrolled narrow-angle glaucoma (high intraocular pressure).
• If you have myasthenia gravis, a condition that causes muscle weakness.
• If you have severe liver disease.
• If you have moderate to severe liver or kidney problems and are taking strong medicines that affect liver enzymes (such as certain antifungal or antibiotic medicines).
• If you have severe ulcerative colitis (severe inflammation of the bowel).
• If you have toxic megacolon, a serious condition that causes extreme widening of the large intestine.

Common side effects of this drug are:

• Dry mouth
• Insomnia
• Dizziness
• Headache
• Abdominal pain

Other General Warnings

• You have difficulty passing urine or conditions like prostate enlargement, as this medicine may increase the risk of urinary retention.
• You have any blockage or narrowing in the stomach or intestines, such as pyloric stenosis.
• You have acid reflux, heartburn, or are taking medicines that can irritate the food pipe, as symptoms may worsen.
• You have slow bowel movements or reduced gut movement.
• You have nerve-related conditions affecting body functions, such as autonomic neuropathy.
• You have controlled narrow-angle glaucoma, as careful monitoring is needed.
• You have liver problems, as dose adjustment or extra monitoring may be required.
• You have kidney problems, so the medication may remain in your body longer.
• You are taking medicines that strongly affect liver enzymes (such as certain antifungals, antibiotics, or antidepressants), as they may increase side effects.
• You plan to increase the dose, especially if you experience dry mouth, constipation, blurred vision, or dizziness.
• Frequent urination is due to other conditions like heart failure or kidney disease, as these should be treated first.
• You have symptoms of a urinary tract infection, such as burning while urinating, fever, or cloudy urine.
• You develop sudden swelling of the face, lips, tongue, or throat; this may indicate a serious allergic reaction.
• You are taking medications such as carbamazepine, rifampicin, or phenytoin, or herbal products such as St John's Wort, as they may reduce the effect of this medicine.
• You have heart problems, low potassium levels, a slow heartbeat, or are taking medicines that affect heart rhythm.
• You have lactose intolerance or problems digesting certain sugars, as this medicine contains lactose.
• You experience headache, stomach upset, or diarrhea after taking this medicine.

How Does It Work?

Interactions with other medicines

• Taking fesoterodine with other medicines that have similar anticholinergic effects (such as some antidepressants, medicines for Parkinson's disease, or certain antipsychotics) may increase side effects like dry mouth, constipation, sleepiness, blurred vision, or difficulty passing urine.
• Fesoterodine may reduce the effect of medications that promote gastrointestinal motility, such as metoclopramide.
• Strong medicines that block liver enzymes (CYP3A4 inhibitors), such as ketoconazole, itraconazole, clarithromycin, and ritonavir, as well as similar antiviral or antifungal drugs, can increase the level of fesoterodine in the body, thereby increasing the risk of side effects. In such cases, the dose of fesoterodine is usually kept low.
• Medicines that moderately affect liver enzymes, such as erythromycin, fluconazole, diltiazem, verapamil, or grapefruit juice, may slightly increase fesoterodine levels, but dose changes are usually not required.
• Medicines that strongly increase liver enzyme activity (CYP3A4 inducers) such as rifampicin, carbamazepine, phenytoin, phenobarbital, or St John's Wort can reduce the effect of fesoterodine, making it less effective. These combinations are generally not recommended.
• Some medicines that block another liver enzyme (CYP2D6 inhibitors) may increase fesoterodine levels in the body, potentially leading to more side effects. A lower dose may be needed in such cases.
• Fesoterodine does not reduce the effectiveness of oral contraceptive pills and does not interfere with birth control hormones.
• Fesoterodine does not significantly affect the action or blood-thinning effect of warfarin.
• Interaction studies with fesoterodine have been conducted only in adults; data in children are limited.

Interactions with food items

• Avoid excessive intake of grapefruit or grapefruit juice while taking Fesoterodine, as it may increase medicine levels in the body and raise the risk of side effects.
• Maintain adequate fluid intake, but avoid drinking large amounts of fluids at one time, as this may worsen overactive bladder symptoms.

Overdose

Missed a Dose