FDA Drug and Device Approvals: May 27, 2004

Yael Waknine

May 27, 2004

The U.S. Food and Drug Administration (FDA) has approved rifaximin for travelers' diarrhea, tinidazole for protozoal and anaerobic infections, a new indication for gemcitabine HCl, the Oculaid/Stableyes Ocular Tension Ring for use in cataract surgery, and the Precision Spinal Cord Stimulator System for chronic pain.

Rifaximin (Xifaxan) Antibiotic for Traveler's Diarrhea

On May 26, the FDA approved rifaximin (Xifaxan, made by Salix Pharmaceuticals, Inc.) as the first nonsystemic, gut-selective, oral antibiotic treatment for travelers' diarrhea (TD) caused by noninvasive strains of Escherichia coli. Rifaximin is available in 200-mg tablets and is intended for use in patients aged 12 years and older.

Unlike systemically absorbed agents currently in use, only 0.4% of rifaximin is absorbed into the bloodstream, thus reducing the potential for development of antimicrobial resistance and other systemic concerns such as drug-drug interactions. Rifaximin is well tolerated and adverse effects are mild.

Rifaximin should not be used in patients with diarrhea complicated by fever or blood in the stool, or diarrhea due to pathogens other than E. coli. It should be discontinued and alternative antibiotic therapy sought if diarrhea symptoms get worse or persist for more than 24 to 48 hours.

Tinidazole (Tindamax) for Protozoal and Anaerobic Infections

On May 26, the FDA approved the antiparasitic agent tinidazole (Tindamax, made by Presutti Laboratories), a compound related to metronidazole. Available in 250-mg and 500-mg tablets, it is indicated for the treatment of trichomoniasis, giardiasis, intestinal amebiasis, and amebic liver abscess.

Tinidazole is a second-generation 5-nitroimidazole compound that has been shown in studies to have a low adverse effect profile, in vitro activity, and a long duration of action (12- to 14-hour half-life).

For trichomoniasis and giardiasis, the treatment regimen is a one-time tinidazole dose of 2 g. Amebiasis is to be treated with tinidazole 2 g daily for three days, and amebic liver abscess requires 2 g daily for three to five days. The tinidazole dosing regimens for giardiasis, amebiasis, and amebic liver abscess are shorter than that of metronidazole.

Clinical studies have shown the effectiveness of tinidazole to be 92% to 100%, 80% to 100%, and 86% to 93% in the treatment of trichomoniasis, giardiasis, and amebiasis, respectively.

New Indication for Gemcitabine HCl (Gemzar) for Metastatic Breast Cancer

On May 19, the FDA approved a third indication for gemcitabine HCl (Gemzar, made by Eli Lilly), allowing its use in combination with paclitaxel (Taxol, made by Bristol-Myers Squibb) as first-line therapy for women with metastatic breast cancer. The combination is intended for use after failure of prior anthracycline-containing adjuvant chemotherapy or in the event that anthracyclines are clinically contraindicated.

The FDA based its approval on results of a phase III study in which patients diagnosed with metastatic breast cancer and treated with the gemcitabine/paclitaxel combination experienced a significant delay in mean time to disease progression compared with those treated with paclitaxel alone (5.2 months vs. 2.9 months; P < .0001).

Oculaid/Stableyes Capsular Tension Ring

On April 27, the FDA approved the Oculaid Capsular Tension Ring (CTR), also known as the Stableyes CTR (both made by Ophtec USA, Inc.). The device is indicated for the stabilization of weakened, broken, or missing zonules that are suspected or observed during cataract extraction using phacoemulsification and continuous curvilinear capsulorhexis techniques in patients aged 12 years and older.

The plastic ring comes in two sizes and is approximately 0.15 to 0.2 mm thick, with a gap on either side to allow proper positioning.

The Oculaid CTR is contraindicated in patients with torn or compromised lens capsular bags that would fail to provide adequate support for the ring, or perforated or damaged lens capsules.

Precision Spinal Cord Stimulator System for Chronic Pain

The Precision Spinal Cord Stimulator System (made by Advanced Bionics Corporation) was approved by the FDA on April 27 for use as an aid in the management of chronic intractable pain of the trunk and/or limbs, including unilateral or bilateral pain associated with failed back surgery syndrome, intractable low back pain, and leg pain.

The device consists of an implanted neurostimulation device (signal generator) that transmits electrical signals to the spinal cord through an insulated lead wire, and an external battery-operated remote control.

Spinal cord stimulation should not be used on patients who are considered by their physician to be poor surgical risks, are pregnant, are unable to operate the system, or who fail to receive effective pain relief during trial stimulation.

Reviewed By Gary D. Vogin, MD


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