Retinoid drug interactions

Adverse effects of tetracyclines include resistant bacteria, folliculitis, candidiasis, gastrointestinal upset, and phototoxic effects. Tetracyclines must not be combined with systemic retinoids because of the increased probability for development of intracranial hypertension. Tetracycline is used in the treatment of moderate to severe acne vulgaris. It is the least expensive of the tetracyclines and therefore often prescribed for initial therapy. A common initial approach includes tetracycline 1 g daily (500 mg twice daily), 1 hour before meals after 1 or 2 months, when marked improvement of inflammatory lesions is observed, the dose may be decreased to 500 mg every day, for another 1 or 2 months. Drawbacks to the use of tetracycline include also a drug-food interaction with dairy prodncts. 

Adapalene (6) is a naphthoic acid derivative with a methoxyphenyl adamant side-chain and is a commonly used antiacne drug [74]. Similar to the adion of tazarotene in its hydrolyzed form, tazarotenic acid, adapalene interacts seledively with RARP and RARy, and its activity on proliferation and differentiation can be blocked by a RARy antagonist [75]. In addition, adapalene has antiinflammatory potential due to its anti-API adivity [75]. Although its efficacy is similar to that of other retinoids, it has an improved therapeutic ratio due to its better tolerance (reviewed in Ref. [76]). 

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