theophylline, Respbid, Slo-Bid, Theo-24, Theolair (cont.)

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Medical and Pharmacy Editor:

Verapamil may reduce blood levels of lithium (Eskalith, Lithobid) in some patients. For unclear reasons some patients who took both verapamil and lithium have noticed increased side effects of lithium without increases in their blood levels of lithium.

The use of "statins" (for example, simvastatin or lovastain) in combination with verapamil has been associated with reports of myopathy/rhabdomyolysis because verapamil reduces the break down of these statins in the liver. The dose of simvastatin in patients on verapamil should not exceed 10 mg daily and the dose of lovastatin (Mevacor, Altoprev) should not exceed 40 mg daily. Lower starting and maintenance doses of other statins (for example, atorvastatin [Liptor]) may be required since verapamil also may increase the plasma concentration of these drugs also. Rifampin and phenobarbital increase the elimination of verapamil, potentially reducing the effect of verapamil.

PREGNANCY: Safety of verapamil during pregnancy has not been established. Verapamil crosses the placenta and enters the fetus.

NURSING MOTHERS: Safety in nursing mothers has not been established. Verapamil is excreted in human milk.

SIDE EFFECTS: Verapamil can cause dizziness, weakness or fainting because of a slow heart rate or low blood pressure. Other side effects include swelling of the lower extremities, rash, headache, nausea, and constipation. Verapamil also can cause mildly abnormal liver tests that usually return to normal with discontinuation of the medication. Verapamil may reduce heart rate. Verapamil also can cause excessive lowering of blood pressure in rare instances. Verapamil can aggravate heart failure, especially in patients with poor function of their heart muscle.

Reference: FDA Prescribing Information

Last Editorial Review: 2/29/2012

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