An HPLC assay for daptomycin in serum

The lipopeptides have a unique mode of action.1 Although they are active against all clinically important Gram-positive bacteria,2 they display no activity against Gram-negative organ-isms.3,4 Daptomycin has been licensed for the treatment of com-plicated skin and skin structure infections, and for right-sided endocarditis. The approved dosage in the UK is 4 mg/kg daily. For Staphylococcus aureus bacteraemia and endocarditis, a dosage of 6 mg/kg daily is advised (British National Formulary 55, March 2008). However, possibly an even higher dosage, of up to 12 mg/kg daily, may be required for the treatment of deep-seated staphylococcal infections.5 As with all newly licensed drugs, it is important to be able to measure the serum concen-trations in patients with altered physiologies. This will allow for an understanding of the drug’s pharmacokinetics and for the management of patients with multiple organ failure. The aim o