Drug Interactions Alcohol: nessuna prescrizione verapamil Verapamil may increase blood alcohol concentrations and prolong its effects. Trough concentrations occur approximately hours after bedtime dosing while the patient is sleeping. Tedisamil treatment may implicate coadministration with class IV antiarrhythmics such as verapamil, P-glycoprotein inhibitor. Com provides free, accurate and independent advice on more than 24,000 prescription drugs, over-the-counter medicines natural products. Duration of treatment will depend on the underlying cause and history of recurrence. Atrial fibrillation or flutter with rapid ventricular response not otherwise controllable with digitalis preparations. Less serious side effects may include: constipation, skin rash or dizziness, headache, tired or warmth, itching, redness, or tingly feeling under your skin.