Following oral administration, calan is quickly and completely absorbed from the digestive tract. Calan has a bioavailability of about 64%. After oral administration, peak plasma concentrations of Calan are reached in 1 to 2 hours.
Cytochrome P450 3A4 (CYP3A4) extensively metabolizes calan in the liver to produce inactive metabolites. The primary metabolite, norverapamil, has pharmacologic properties that are comparable to those of verapamil.
About 70% of the dose of verapamil and its metabolites are excreted in the urine, with the remaining 30% passing primarily through the feces.
Verapamil has an elimination half-life of 3–4 hours.
For specific dosing advice, speak to your healthcare provider.
Calan can interact with other medications. Tell your doctor about all the medications you are taking, including over-the-counter drugs and supplements.
Calan can interact with the following medications:
* grapefruit juice
Calan can also interact with certain herbs and supplements. Tell your doctor about all the herbs and supplements you are taking. Herbs and supplements that can interact with Calan include:
* St. John’s wort
* Horse chestnut seed extract
Be sure to tell your doctor about all the medications and herbs and supplements you are taking before starting Calan.
The most common side effects of Calan include:
Some side effects of Calan can be serious. If you experience any of the following side effects, call your doctor immediately:
* slow or irregular heartbeat
* shortness of breath
* chest pain
* swelling of the ankles, feet, or legs
a rare but serious side effect of Calan is a condition called AV block, which can be life-threatening. Call your doctor immediately if you experience any of the following symptoms:
Dosage and Administration
Calan should be administered twice daily at an 80 mg starting dose. Depending on how you react to the medication, your doctor may change the dose you are given. The maximum daily dose advised is 480 mg.
Taking Calan with or without food is an option. Calan should be taken with food if you have stomach discomfort.
Take your missed Calan dose as soon as you remember. Skip the missed dose and carry on with your regular dosing schedule if it is almost time for your next dose. Never take two Calan doses at the same time.
Call your doctor or visit the closest emergency room if you accidentally take too much Calan.
Store Calan away from heat and light at room temperature. Keep Calan away from children and animals.
This information is provided solely for educational purposes and does not represent medical advice. The information presented here is not meant to replace consultations with a healthcare professional. A healthcare professional should always be consulted before beginning or changing any treatment. This medication guide does not include all interactions that might occur. Consult your physician, nurse, or pharmacist if you have any concerns about the medications you are taking.