Dermatological pharmacology: systemic drugs

In recent years there has been an evolution in the systemic therapy of skin disease, in particular immunosuppressive agents, retinoids and, most lately, biological drugs and new classes of drugs for advanced skin cancer. Developments in drug monitoring include measurement of thiopurine methyl transferase enzyme activity before prescribing azathioprine, to screen for patients at risk of severe bone marrow depression, and monitoring recipients of methotrexate with procollagen III peptide or Fibroscans to detect hepatic fibrosis. Biologics including anti-tumour necrosis factor α therapy offer a new and effective treatment for severe psoriasis in patients who have failed to respond to conventional systemic drugs, but risks include reactivation of tuberculosis. Oral retinoid therapy has expanded to include alitretinoin, a new oral drug for severe hand eczema, and stringent requirements have been introduced for females treated with isotretinoin due to the high risk of birth deformity which is common to these drugs. It is important that physicians are aware of the adverse effects of treatment and that patients are carefully selected screened and monitored to minimize any risk.