60 MG, 90 MG, 180 MG,
240 MG, 300 MG,
60 MG, AND 420 MG
Muscle contraction is governed by the flow of calcium through what are called "voltage-gated calcium channels." When these channels are blocked by drugs, less calcium can flow through the channels. This results in a weaker muscle contraction. Blood calcium levels are not altered by this blockade.
The voltage-gated calcium channels that one might wish to block are located in heart muscle and in blood vessels. The use of calcium channel blockers would lead to a more relaxed and therefore dilated blood vessels which, in turn, translates to lower blood pressure. The heart ends up with less resistance to pump against, meaning that the heart does not have to work as hard. In situations where the heart muscle might be overworked, this might lead to a more efficient and healthier heart.
Diltiazem also affects the electrical conduction of the heart such that electrical conduction is slowed. This means that the heart rate also slows, allowing for a longer filling time for the heart between pumps.
Diltiazem is most commonly used in the treatment of hypertrophic cardiomyopathy in the cat. In this condition, the heart muscle becomes stiff and inflexible plus the filling chambers of the heart become smaller. The muscle-bound heart cannot fill normally for these reasons and since it cannot fill normally, it sends forth less blood with each pump. To meet the oxygen demands of the body, the heart pumps faster since it is pumping out less blood per pump.
By using a calcium channel blocker such as diltiazem, the heart may fill more efficiently.
Diltiazem might also be used in the treatment of hypertension.
The most commonly reported side effect in the cat is vomiting. Other side effects include: low blood pressure and consequent listlessness, slow heart rate and heart arrythmias.
Diltiazem should not be used with beta-blockers (heart medications which might compound the low blood pressure side effect) such as atenolol or propranolol.
Cimetidine (an antacid) may increase the blood levels of diltiazem (making the effects of diltiazem stronger). Ranitidine, another anacid, also has this effect but not as strongly.
- Diltiazem should not be used in conditions where reduced strength of heart contraction or further slowing the heart rate could be dangerous. Such situations might include congestive heart failure, AV blockage-type heart arrhythmias, or low blood pressure.
- Diltiazem should be avoided in patients with liver impairment or kidney failure. If use cannot be avoided, dose changes will likely be needed.
- Diltiazem should not be used in pregnancy.
- Diltiazem should be stored at room temperature and protected from light.
Page posted: 12/22/10