Side Effects of Detrol (tolterodine)

Detrol (tolterodine) is a cholinergic (acetylcholine) receptor blocker used to treat disorders of the urinary bladder that affect urination. 

Urine coming from the kidneys fills the bladder and causes it to stretch like a balloon. As it stretches, pressure in the bladder increases and when the bladder reaches a certain level of stretch, an urge to urinate is felt. Nerves in the muscular wall of the bladder release acetylcholine, a chemical that attaches to receptors on the muscle cells and causes the cells to contract (tighten). 

This contributes further to the increase in pressure within the bladder and the desire to urinate. Normally, urination is under conscious control but in some individuals normal control as well as normal sensation are lost. The desire to urinate may be felt when there is little urine in the bladder, and urination may occur without warning or control. 

By blocking the effect of acetylcholine on the muscle cells, Detrol slows the build-up of pressure in the bladder, reduces the sensation to urinate, and prevents uncontrolled urination. 

Common side effects of Detrol include:

• dry mouth,
• dry eyes,
• headache,
• upset stomach,
• dizziness,
• drowsiness,
• constipation, and
• blurred vision. 

Caution is recommended for patients with narrow-angle glaucoma, obstruction to the flow of urine, or poor emptying of the stomach since Detrol may worsen these medical conditions.

Drug interactions of Detrol include the following, which raise Detrol blood levels and lead to side effects:

• erythromycin,
• clarithromycin,
• ketoconazole,
• itraconazole,
• cyclosporine,
• vinblastine, and
• miconazole. 

At doses much greater than those used in humans, Detrol causes fetal abnormalities in animals, but there are no studies with Detrol in pregnant women. Detrol should only be given to pregnant women if benefits are felt to outweigh potential risks. 

It is unknown if Detrol is secreted into breast milk. Nursing mothers should either not breastfeed or discontinue Detrol.

The most common side effects of tolterodine are:

• dry mouth,
• dry eyes,
• headache,
• upset stomach,
• dizziness,
• drowziness, and
• constipation.

Tolterodine also may cause blurred vision. Caution is recommended for patients with narrow-angle glaucoma, obstruction to the flow of urine, or poor emptying of the stomach since tolterodine may worsen these medical conditions.

The Phase 2 and 3 clinical trial program for Detrol Tablets included 3071 patients who were treated with Detrol (N=2133) or placebo (N=938). The patients were treated with 1, 2, 4, or 8 mg/day for up to 12 months. No differences in the safety profile of tolterodine were identified based on age, gender, race, or metabolism.

The data described below reflect exposure to Detrol 2 mg bid in 986 patients and to placebo in 683 patients exposed for 12 weeks in five Phase 3, controlled clinical studies. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The adverse reaction information from clinical trials does, however, provide a basis for identifying the adverse events that appear to be related to drug use and approximating rates.

Sixty-six percent of patients receiving Detrol 2 mg bid reported adverse events versus 56% of placebo patients. The most common adverse events reported by patients receiving Detrol were:

• dry mouth,
• headache,
• constipation,
• vertigo/dizziness, and
• abdominal pain.

Expected side effects of antimuscarinic agents are:

• dry mouth,
• constipation,
• abnormal vision (accommodation abnormalities),
• urinary retention, and
• xerophthalmia.

Dry mouth was the most frequently reported adverse event for patients treated with Detrol 2 mg bid in the Phase 3 clinical studies, occurring in 34.8% of patients treated with Detrol and 9.8% of placebo-treated patients. One percent of patients treated with Detrol discontinued treatment due to dry mouth.

The frequency of discontinuation due to adverse events was highest during the first 4 weeks of treatment. Seven percent of patients treated with Detrol 2 mg bid discontinued treatment due to adverse events versus 6% of placebo patients. The most common adverse events leading to discontinuation of Detrol were dizziness and headache.

Three percent of patients treated with Detrol 2 mg bid reported a serious adverse event versus 4% of placebo patients. Significant ECG changes in QT and QTc have not been demonstrated in clinical-study patients treated with Detrol 2 mg bid. Table 5 lists the adverse events reported in 1% or more of the patients treated with Detrol 2 mg bid in the 12-week studies. The adverse events are reported regardless of causality.

Table 5: Incidence* (%) of Adverse Events Exceeding Placebo Rate and Reported in > 1% of Patients Treated with Detrol Tablets (2 mg bid) in 12-week, Phase 3 Clinical Studies

Post-marketing Surveillance

The following events have been reported in association with tolterodine use in worldwide post-marketing experience:

General: anaphylaxis and angioedema;

Cardiovascular: tachycardia, palpitations, peripheral edema;

Central/Peripheral Nervous: confusion, disorientation, memory impairment, hallucinations.

Reports of aggravation of symptoms of dementia (e.g., confusion, disorientation, delusion) have been reported after tolterodine therapy was initiated in patients taking cholinesterase inhibitors for the treatment of dementia.

Because these spontaneously reported events are from the worldwide post-marketing experience, the frequency of events and the role of tolterodine in their causation cannot be reliably determined.

CYP3A4 Inhibitors

Ketoconazole, an inhibitor of the drug metabolizing enzyme CYP3A4, significantly increased plasma concentrations of tolterodine when coadministered to subjects who were poor metabolizers, Variability in Metabolism and Drug-Drug Interactions). For patients receiving ketoconazole or other potent CYP3A4 inhibitors such as other azole antifungals (e.g., itraconazole, miconazole) or macrolide antibiotics (e.g., erythromycin, clarithromycin) or cyclosporine or vinblastine, the recommended dose of Detrol is 1 mg twice daily.

Drug-Laboratory-Test Interactions

Interactions between tolterodine and laboratory tests have not been studied.