Amlodipine (Norvasc )
ingested, amlodipine becomes completely absorbed in the small
intestine. Neither absorbability nor bioavailability of the drug
changes when administered with food.
Renal elimination of ten inactive metabolites formed in the liver is
the only way of excretion. Users with renal insufficiency experience
just a slight difference in the main pharmacokinetic parameters of
amlodipine. It ensures safe treatment of the elderly, who often have
some degree of renal dysfunction. One should be cautious when using
amlodipine to cure patients with liver cirrhosis.
Amlodipine is mainly used to treat primary hypertension and other
forms of arterial hypertension.
Amlodipine can be prescribed as initial treatment for myocardial
ischemia caused by a permanent obstruction (stable angina) or
coronary artery spasms (Prinzmetal's angina or variant angina
pectoris). It may also work well in cases when the presence of a
vasospastic (vasoconstrictive) agent is possible.
Amlodipine is easily tolerated. Clinical placebo trials, involving
patients with hypertension and angina, showed that the most common
side effects: headache, edema, fatigue, nausea, flushing and
dizziness. Any characteristic of clinically significant
abnormalities on laboratory tests in the test amlodipine were noted.
The trials didn’t reveal any discrepancies in the results of
Although elderly patients may have a higher concentration of
amlodipine in plasma, its half-life remains unchanged. Amlodipine is
equally well tolerated by both elderly and younger patients.
Therefore, a regular drug therapy is recommended.
patients with renal failure 10% of amlodipine is recovered in urine
in unchanged form, as inactive metabolites. Changes in plasma
concentrations of amlodipine are affected by the degree of renal
failure. To treat such patients regular doses of amlodipine can be
used. Amlodipine cannot be eliminated during dialysis. The half-life
of amlodipine is increased in patients with impaired liver function.
The recommended dose for such cases has not been established.
Therefore, additional safety measures should be taken.
Pregnancy and breast-feeding
Safety level of amlodipine administration during pregnancy and
lactation has not yet been established. Pregnant animal studies show
no signs of amlodipine’s toxicity except childbirth delay and labor
increase in rats at a dose 50 times as high as the maximum
recommended human dose. Thus, the usage during pregnancy is
recommended only in cases where the benefits a mother and a child
may get outweigh the potential risks.
There are no document supported cases of amlodipine overdose. Since
the absorption of amlodipine is slow, gastric lavage might be
carried out in some cases. Available data suggest that a strong
overdose can cause excessive peripheral vasodilation, which can
result in replacement and prolonged systemic hypotension. Clinically
significant hypotension caused by amlodipine overdose requires
active measures to be taken to support the cardiovascular system,
including the monitoring of cardiac and respiratory function and
limb lifting. Particular attention should be paid to maintaining
blood volume and the amount of urine. Vasopressors can be used to
restore vascular tone and blood pressure, provided there are no
contraindications. Since amlodipine is largely protein bound,
dialysis is unlikely to be of any help.
Amlodipine can be safely used in combination with thiazide
diuretics, beta-blockers, ACE inhibitors, long-acting nitrates,
sublingual nitroglycerin, NSAIDs, antibiotics, and oral hypoglycemic
drugs. Additional research has shown that the simultaneous use of
amlodipine and digoxin neither alters the level of digoxin in serum
nor renal excretion of digoxin, and administration of cimetidine
does not affect the pharmacokinetics of amlodipine. In vitro studies
indicate that amlodipine has no effect on protein binding of such
drugs as digoxin, phenytoin, warfarin, and indomethacin.
usual starting dose for hypertension and angina pectoris is 5 mg one
time per day. This dose may be increased to 10 mg, depending on an
individual patient response.