Drug Interaction Report

CONTRAINDICATED: Concomitant use of systemic vitamin A derivatives (e.g., retinoids) with tetracyclines may increase the risk of pseudotumor cerebri, also known as benign intracranial hypertension. These agents have each been individually associated with the development of pseudotumor cerebri and may have additive effects if administered concurrently. This interaction has been suspected in reported cases involving the use of some retinoids (e.g., isotretinoin) in combination with a tetracycline.

MANAGEMENT: Coadministration of most systemic vitamin A derivatives with tetracyclines is considered contraindicated. One publication recommends a drug-free period, or washout, between the two medications. The authors suggest a 7-day washout period if the patient has normal renal and liver function, is using the tetracycline for acne, and is changing from a tetracycline to a vitamin A derivative. All patients should be counseled to contact their healthcare provider immediately if they develop signs or symptoms of pseudotumor cerebri such as papilledema, headache, nausea, vomiting, and/or visual disturbances. The patient should be advised to discontinue the retinoid and tetracycline antibiotic and be referred for immediate neurological evaluation and care if pseudotumor cerebri is suspected as this could result in permanent vision loss.

GENERALLY AVOID: The combined use of ethanol and isotretinoin may result in a disulfiram-like reaction. The mechanism has not been established.

MANAGEMENT: Alcohol consumption should be avoided during isotretinoin therapy.

GENERALLY AVOID: The oral bioavailability of quinolone and tetracycline antibiotics may be reduced by concurrent administration of preparations containing polyvalent cations such as aluminum, calcium, iron, magnesium, and zinc. Therapeutic failure may result. The proposed mechanism is chelation of quinolone and tetracycline antibiotics by di- and trivalent cations, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. Reduced gastrointestinal absorption of the cations should also be considered.

MANAGEMENT: Concomitant administration of oral quinolone and tetracycline antibiotics with preparations containing aluminum, calcium, iron, magnesium, and/or zinc salts should generally be avoided. Otherwise, the times of administration should be staggered by as much as possible to minimize the potential for interaction. Quinolones should typically be dosed either 2 to 4 hours before or 4 to 6 hours after polyvalent cation preparations, depending on the quinolone and formulation. Likewise, tetracyclines and polyvalent cation preparations should typically be administered 2 to 4 hours apart. The prescribing information for the antibiotic should be consulted for more specific dosing recommendations.