The use and safety of doxycycline hyclate and other second-generation tetracyclines

Tetracyclines have long been used to treat a wide variety of medical conditions, especially in the field of dermatology. Unfortunately, safety concerns, especially gastrointestinal (GI), have always been present. Other safety concerns have included tooth development in children, candidiasis, vestibular concerns, photosensitivity/phototoxicity, and more unusual adverse effects such as uncontrolled hypertension. This article first discusses the pharmacological development of the tetracyclines from the first to the second generation versions with an emphasis on the safety concerns, especially with regards to doxycycline hyclate (DH). Second, the adverse effects of the tetracyclines are discussed. Third, the favorable side effect profile of DH delayed release capsules (Doryx) is compared with DH powder contained in tablets (Vibramycin). Fourth, the increased use with a continued favorable safety profile is also discussed concerning the subantimicrobial dosing of DH for acne. Fifth, the safety of periodontic uses of DH is discussed. Last, the favorable safety profiles of the 2006 approved uses of an anti-inflammatory dose of 40 mg doxycycline for rosacea and an extended-release minocycline tablet for acne are also discussed.