Magazine article Drug Topics

Three in One

Magazine article Drug Topics

Three in One

Article excerpt

Triple therapy to treat AIDS patients now available in one convenient tablet

Three nucleoside analog reverse transcriptase inhibitors (NRTIs), have been packaged into one tablet by Glaxo Wellcome Inc. The result is Trizivir, which contains 300 mg of abacavir (Ziagen), 150 mg of lamivudine (Epivir), and 300 mg of zidovudine (Retrovir).

Glaxo had already combined lamivudine and zidovudine into a twice-daily tablet, Combivir. The addition of abacavir, another twice-- daily medication, thus cuts the number of daily tablets from four to two for patients taking all three NRTIs. And pharmacokinetic data support the claim that Trizivir can be taken without regard to food or fluid intake.

Does a reduction of two tablets really make a difference for patients? "When we developed Combivir, we didn't really think it would make a significant difference," said Amy Keller, International Project Team Leader for the Trizivir project. "But according to patients, it has made a significant difference." The benefit from the patient's viewpoint depends upon "how many other medications the patient is taking [and] the kinds of medications the patient is taking," she said. For example, patients on medications that must be taken with water were more likely to appreciate the lack of food and water restrictions with Trizivir.

Alan Schorejs has been taking Trizivir since June 2000. "The nice thing is that it is only twice a day," he said. For Schorejs, who needs 10 hours' sleep a day, taking medications four times a day is, to say the least, inconvenient. "I have friends ... who take 20 tabs a day, three or four times a day," he added. For these patients, too, he feels a reduction of two tablets a day will be much appreciated.

Keller admitted that triple-NRTI therapy is not necessarily the current therapy of choice for patients infected with HIV. "Historically, the standard of care has been a protease inhibitor and two nucleosides," she said. More recently, a non-nucleoside RTI, efavirenz (Sustiva, DuPont Pharma), has been gaining popularity Keller does believe that triple-NRTI use is on the rise. "I think triple-nucleoside therapy is an area where we've seen an increase [in use]," she said, adding that the therapy has increased regularly by 5%-7%. "It's going to be an evolving paradigm."

A potential advantage of Trizivir is it may simplify dosing with multiple drugs. Keller noted the example of "quad therapy" Trizivir "gives three of four drugs in a very simple way."

One disadvantage to Trizivir is lack of flexibility in dosing. The product is not appropriate for patients who require dose adjustments, such as those with renal insufficiency (creatinine clearance > 50 ml/min), dose-- limiting side effects, or patients weighing less than 40 kg. Warnings to this effect are included in the product labeling. Another problem is that with all three drugs come all of the associated adverse reactions. In particular, abacavir can cause a potentially fatal hypersensitivity reaction in about 5% of patients. Signs and symptoms of this event may be confused with certain other disorders, such as gastroenteritis and acute onset respiratory diseases, according to the prescribing information for Trizivir.

Zidovudine therapy has resulted in hematologic toxicities in some patients. In at least one study, approximately 7% of patients had neutropenia, and another 3% were anemic. …

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