Minocycline

Absorption of minocycline is impaired by the concomitant administration of antacids, iron, calcium, aluminium, magnesium and zinc salts (interactions with specified salts, antacids and kaolin). Dosages should be maximally separated.

Tetracyclines depress plasma prothrombin activity and reduced dosages of concomitant anticoagulants may be necessary.

Increased risk of ergotism.

Both can induce hyperpigmentation.

Minocycline should not be used with penicillins.

Administration of isotretinoin should be avoided shortly before, during and shortly after minocycline therapy. Each drug alone has been associated with pseudotumor cerebri (benign intracranial hypertension).

Absorption of minocycline decreased by quinapril (which contains magnesium carbonate).

Absorption of minocycline decreased by sucralfate and bismuth salts.

As with other tetracyclines, minocycline may cause hyperpigmentation at various body sites. Hyperpigmentation may present regardless of dose or duration of therapy but develops more commonly during long term treatment. Patients should be advised to report any unusual pigmentation without delay and minocycline should be discontinued. This is generally reversible on cessation of therapy.

If photosensitivity occurs, patients should be warned to avoid direct exposure to natural or artificial light and to discontinue therapy at the first sign of discomfort.

As with other tetracyclines, bulging fontanelles in infants and benign intracranial hypertension in juveniles and adults have been reported. Presenting features were headache and visual disturbances including blurring of vision, scotoma and diplopia. Permanent vision loss has been reported. Treatment should cease if evidence of raised intracranial pressure develops.

Tetracyclines can cause weak neuromuscular blockade – use with caution in Myasthenia Gravis.

Results of animal studies indicate that tetracyclines cross the placenta and are found in foetal tissues and can have toxic effects on the developing foetus (often related to retardation of skeletal development). Evidence of embryotoxicity has also been noted in animals treated early in pregnancy. Minocycline should not therefore be used in pregnancy unless considered essential.

The use of drugs of the tetracycline class during tooth development (last half of pregnancy) may cause permanent discoloration of the teeth (yellow-grey brown). This adverse reaction is more common during long-term use of the drugs but has been observed following repeated short-term courses. Enamel hypoplasia has also been reported.

Tetracyclines have been found in the milk of lactating women who are taking a drug in this class. Permanent tooth discoloration may occur in the developing infant and enamel hypoplasia has been reported.

Light headedness, visual disturbances, dizziness, tinnitus and vertigo have occurred with minocycline and patients should be warned about the possible hazards of driving or operating machinery during treatment.