GlaxoSmithKline’s nucleoside reverse transcriptase inhibitor (NRTI) abacavir (Ziagen) has received approval for once daily dosing for HIV treatment from the European Medicines Agency. This approval adds to the growing list of anti-HIV drugs that can be taken once daily, reducing pill burden and increasing patient satisfaction and possibly adherence.
Abacavir was approved in Europe at a dose of 300mg twice daily in July 1999. This week’s approval of once daily abacavir at a dose of 600mg follows on from the results of the ZODIAC trial, published earlier this year, which demonstrated equivalence in safety and effectiveness between once and twice daily formulations, when combined with 3TC.
The co-formulation Kivexa, already approved for marketing as Epzicom in the United States, contains 600mg abacavir and 300mg 3TC. This combination is likely to become a widely-used option in first-line and subsequent antiretroviral therapy regimens once it receives European approval, probably next year. Kivexa is current available in the United Kingdom on a named-patient basis.
Abacavir has been shown to be a highly potent drug for use in first-line anti-HIV therapy, although it is also useful in patients who have failed one or more drug regimens. It can be taken with or without food.
The drug’s most significant side-effect is a potentially life-threatening hypersensitivity reaction that occurs within the first few weeks of therapy in around four per cent of patients. This is characterised by flu-like symptoms, notably fever, which generally worsen with additional drug doses. Permanent discontinuation of abacavir is usually recommended.
More common side-effects of abacavir include nausea, vomiting, fatigue and lethargy, although these are usually mild and resolve within the first few weeks of therapy.