Description

Minocycline, 7-dimethylamino-6-demethyl-6-deoxytetracycline(Minocin, Vectrin), the most potent tetracycline currentlyused in therapy, is obtained by reductive methylationof 7-nitro-6-demethyl-6-deoxytetracycline. It was releasedfor use in the United States in 1971. Because minocycline,like doxycycline, lacks the 6-hydroxyl group, it is stablein acids and does not dehydrate or rearrange to anhydroor lactone forms. Minocycline is well absorbed orally togive high plasma and tissue levels. It has a very long serumhalf-life, resulting from slow urinary excretion and moderateprotein binding. Doxycycline and minocycline, alongwith oxytetracycline, show the least in vitro calcium bindingof the clinically available tetracyclines. The improved distributionproperties of the 6-deoxytetracyclines have been attributedto greater lipid solubility. Perhaps the most outstanding property of minocyclineis its activity toward Gram-positive bacteria, especiallystaphylococci and streptococci. In fact, minocycline hasbeen effective against staphylococcal strains that are resistantto methicillin and all other tetracyclines, includingdoxycycline. Although it is doubtful that minocyclinewill replace bactericidal agents for the treatment of lifethreateningstaphylococcal infections, it may become auseful alternative for the treatment of less serious tissueinfections. Minocycline has been recommended for thetreatment of chronic bronchitis and other upper respiratorytract infections. Despite its relatively low renal clearance,partially compensated for by high serum and tissuelevels, it has been recommended for the treatment of urinary tract infections. It has been effective in the eradicationof N. meningitidis in asymptomatic carriers.