For lactating mothers it is not known whether clarithromycin is excreted in human milk. Interactions
Clarithromycin inhibits a liver enzyme, CYP3A4, involved in the metabolism of many other commonly prescribed drugs. Taking clarithromycin with other medications that are metabolized by CYP3A4 may lead to unexpected increases or decreases in drug levels. A few of the common interactions are listed below. Colchicine
Clarithromycin has been observed to have a dangerous interaction with colchicine as the result of inhibition of CYP3A4 metabolism and P-glycoprotein transport. Combining these two drugs may lead to fatal colchicine toxicity, particularly in people with chronic kidney disease. Statins
Taking clarithromycin concurrently with certain statins (a class of drugs used to reduce blood serum cholesterol levels) increases the risk of side effects, such as muscle aches and muscle break down (rhabdomyolysis). Calcium channel blockers
Concurrent therapy with calcium channel blocker may increase risk of low blood pressure, kidney failure, and death, compared to pairing calcium channel blockers with azithromycin, a drug similar to clarithromycin but without CYP3A4 inhibition. Administration of clarithromycin in combination with verapamil have been observed to cause low blood pressure, low heart rate, and lactic acidosis. Carbamazepine
Clarithromycin may double the level of carbamazepine in the body by reducing its clearance, which may lead to toxic symptoms of carbamazepine, such as double vision, loss of voluntary body movement, and nausea, as well as hyponatremia. HIV medications
Depending on the combination of medications, clarithromycin therapy could be contraindicated, require changing doses of some medications, or be acceptable without dose adjustments.
Tetany or tetanic seizure is a medical sign consisting of the involuntary contraction of muscles, which may be caused by disorders that increase the action potential frequency of muscle cells or the nerves that innervate them. Muscle cramps caused by the disease tetanus are not classified as tetany; rather, they are due to a lack of inhibition to the neurons that supply muscles. Tetanic contractions (physiologic tetanus) are a broad range of muscle contraction types, of which tetany is only one. Signs and symptoms
Tetany is characterized by contraction of distal muscles of the hands (carpal spasm with extension of interphalangeal joints and adduction and flexion of the metacarpophalangeal joints) and feet (pedal spasm) and is associated with tingling around the mouth and distally in the limbs. Causes
The usual cause of tetany is a deficiency of calcium. An excess of phosphate (high phosphate-to-calcium ratio) can also trigger the spasms. Underfunction of the parathyroid gland can lead to tetany. Low levels of carbon dioxide cause tetany by altering the albumin binding of calcium such that the ionized (physiologically influencing) fraction of calcium is reduced; one common reason for low carbon dioxide levels is hyperventilation. Low levels of magnesium can lead to tetany. Clostridium tetani toxin, via inhibition of glycine-mediated and GABA-ergic neurotransmission, may lead to tetany.An excess of potassium in grass hay or pasture can trigger winter tetany, or grass tetany, in ruminants. Osteomalacia and rickets due to deficiency of vitamin DMetabolic alkalosis with hypokalemia like Gitelman syndrome  and Bartters syndrome can cause tetany.