DOSAGE: The usual dosage for adults is 250 mg every 6 hours, 333 mg every 8 hours or 500 mg every 12 hours. Doses may be increased up to 4 g/day according to the severity of the infection.
In children, the usual dosage is 30 to 50 mg/kg/day with age, weight, and severity of the infection being taken into consideration to determine the appropriate dosage.
Erythromycin may be taken with or without food; however optimal blood levels of erythromycin are obtained when taken on an empty stomach (at least 30 minutes and preferably 2 hours before or after meals).
DRUG INTERACTIONS: Erythromycin when used with antiarrhythmic drugs such as, amiodarone (Cordarone), bretylium (Bretylol), disopyramide (Norpace), dofetilide (Tikosyn), procainamide (Pronestyl), quinidine (Quinaglute, Quinidex, Quinora) and sotalol (Betapace) exaggerates the effect of the antiarrhythmic drugs which may give rise to abnormal heart rhythms such as torsades de pointes.
Theophyllines such as theophylline (Theo-Dur), oxtriphylline (Choledyl SA), and aminophylline (Phyllocontin) reduce erythromycin blood levels by increasing elimination of erythromycin by the kidneys, which may reduce the effectiveness of erythromycin. Conversely, erythromycin inhibits the metabolism (breakdown) of theophyllines by the liver and causes an increase in blood levels of theophylline. High theophylline levels may give rise to side effects such as seizures and disturbances in heart rhythm. Therefore, the dose of theophyllines should be reduced or theophylline levels in the blood should be measured in patients taking erythromycin.
Combining erythromycin with ergotamine or ydroergotamine has been associated with acute ergot toxicity. This combination should be avoided.
Erythromycin prevents digoxin (Lanoxin) from being eliminated by the kidneys; this in turn causes increased levels of digoxin in the blood. Increased levels of digoxin can cause disturbances in heart rhythm. Therefore, it is important to monitor and adjust digoxin doses when treating with erythromycin.
Erythromycin prevents the elimination of warfarin (Coumadin) from the body which can raise the levels of warfarin in the blood. Warfarin is an anticoagulant or blood thinner, and an increase in its level in blood can increase the risk of bleeding. It is important to monitor the effects of warfarin and adjust warfarin doses when treating with erythromycin.
Erythromycin inhibits the breakdown of HMG-CoA reductase inhibitors (statins) such as atorvastatin (Lipitor), lovastatin (Mevacor) and simvastatin (Zocor) by the liver leading to increased levels of statins in the blood. High levels of statins could result in severe myopathy (muscle damage) with rhabdomyolysis (r (rapid breakdown of skeletal muscle) that may damage the kidneys or even lead to death. Erythromycin also can elevate blood levels of some anti-seizure drugs such as carbamazepine (Tegretol) by preventing the breakdown of the anti-seizure drug by the liver. Therefore, doses of the anti-seizure drugs may need to be reduced during treatment with erythromycin. Erythromycin also increases blood levels of sildenafil (Viagra). The dose of sildenafil should be reduced when treating with erythromycin.
Grapefruit juice may prevent the breakdown of erythromycin, resulting in elevated levels of erythromycin in the blood. Therefore, it is important to avoid eating grapefruit or drinking grapefruit juice during treatment with erythromycin.
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