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Cardizem SR (diltiazem) is a calcium channel blocker administered to treat angina, hypertension, and certain varieties of arrhythmia. Cardizem SR relaxes the smooth muscle of arterial walls, increasing their inner diameter, allowing blood to flow with less restriction and lowering blood pressure. Cardizem SR also encourages the heart to slow the speed and strength of individual heartbeats, producing a further reduction in blood pressure.

Cardizem SR has also seen off-label use as an effective migraine prevention treatment. Additionally the medication is being used in the treatment of anal fissures.

The SR in this product stands for sustained release, an all-day formula that slowly releases the medication. Because of the way this tablet is formulated, it is important that it be swallowed whole and not be crushed, chewed, dissolved, or otherwise damaged. Patients unable to swallow whole tablets may want to speak with a doctor or pharmacist about other options.

Getting the Most from Cardizem SR

Cardizem SR is administered by tablets or capsules, and may be taken with or without food according to doctor instruction.

In both angina and hypertension, a starter dose of Cardizem SR is one 120 to 180 mg tablet by mouth once a day. In both cases it will take about 14 days for full benefit to be seen; dosage adjustments should not be made before then. After 14 days at lower doses, dosage may be increased, if needed, up to 480 mg, again taken once per day.

In hypertension, Cardizem SR should be producing full benefit in 14 days. It's not unusual for other hypertension treatments to be taken along with Cardizem SR. Use may continue for as long as the medication provides benefit, but be aware that other medications can influence Cardizem SR; adjustments may be necessary when other medications are added, removed, or modified.

In treating angina, it's most important to be aware that Cardizem SR reduces the frequency and duration of angina attacks, but does not necessarily stop them altogether and will do nothing to address chest pain currently being experienced. For this reason a doctor may prescribe other medications to alleviate acute chest pain.

Important Precautions

Due to the potential for additive effects, caution is warranted in patients receiving Cardizem SR along with any agents known to affect cardiac function.

Cardizem SR is a substrate and an inhibitor of the cytochrome P-450 3A4 enzyme system. Other drugs that are specific substrates, inhibitors, or inducers of this enzyme system may have a significant impact on the efficacy and side effect profile of Cardizem SR. Patients taking other drugs that are substrates of CYP450 3A4, especially patients with renal or hepatic impairment, may require dosage adjustment when starting or stopping them in order to maintain optimum therapeutic blood levels.

Incidence of side effects while taking Cardizem SR is comparable to those experienced by patients taking placebo. Less than 3% of patients taking Cardizem SR reported:

• Edema
• Headache
• Nausea
• Rash
• Dizziness
• Weakness
• Fatigue

The above symptoms are not cause for concern unless severe enough to be disruptive.

Cardizem SR lowers blood pressure; as such, patients may experience side effects mimicking that of low blood pressure, even though the blood pressure dropped from too-high to normal. Patients should be alert for the warning signs and be prepared to deal with them:

• Lightheadedness
• Severe nausea
• Clammy skin
• Blurry vision
• Depression
• Severe fatigue
• Severe Dizziness
• Loss of consciousness

The above can often be managed with a bit of care; moving slowly, getting up from a resting position slowly, reducing emotional stress and so forth can help. If the side effects are simply from a change in blood pressure they should stop occurring after a few days, and of course blood pressure readings will say blood pressure is within normal range. If modifying behavior doesn't work, blood pressure readings say blood pressure is too high or low, or if severe consequences like loss of consciousness are experienced, emergency medical attention should be sought.