CYP3A4 and myopathy: Drug interactions between CYP3A4 substrates such as simvastatin and CYP3A4 inhibitors are potentially clinically important and have been reported to potentially enhance the risk of myopathy and rhabdomyolysis (Walker, 1989; Todd and Goa, 1990; Berland et al, 1991; Smith et al, 1991; Garnett, 1995; Meier et al, 1995; Goodman & Gilman's, The Pharmacological Basis of Therapeutics, 2000).