ABBOTT WITHDRAWAL OF OMNIFLOX FOLLOWS 50 SERIOUS ADVERSE REACTIONS

ABBOTT WITHDRAWAL OF OMNIFLOX FOLLOWS 50 SERIOUS ADVERSE REACTIONS since the oral antibiotic was launched in the U.S., FDA said in a press release issued following Abbott's June 5 announcement that the company is voluntarily withdrawing the broad-spectrum quinolone temafloxacin. "There have been approximately 50 reports of serious adverse reactions, including three deaths" since the product was introduced in mid-February, FDA said. Omniflox was approved Jan. 30 for the treatment of respiratory, skin, prostate and urinary tract infections. The adverse reactions associated with Omniflox include "several cases of severe low blood sugar, especially in very elderly patients with decreased kidney function," FDA said. "Among the severe reactions there were a number of cases of an unusual complex of adverse reactions consisting of hemolytic anemia (destruction of red blood cells) and other blood cell abnormalities," the agency said. "Also observed were patients with kidney dysfunction, about half of [whom] required renal dialysis. Other patients suffered liver dysfunction." In response to the findings, Abbott said in a June 5 press release that "it will voluntarily withdraw [Omniflox] from the worldwide market." Some of the reactions cited by FDA were reported outside the U.S. Omniflox is also marketed in Italy, the U.K., Germany, Ireland, Sweden and Argentina and is pending approval in 30 other countries. Abbott said it began the recall process on June 5. Omniflox labeling contains no indication of the types of reactions seen in the adverse reaction reports, except for concerns about renal impairment. Approved labeling notes that "most of the adverse events reported were mild to moderate in severity and transient in nature." Moreover, "the overall adverse reaction rate in healthy human subjects was no different between temafloxacin and placebo." For elderly patients, labeling states that "dosage adjustment is necessary only" with renal impairment ("The Pink Sheet" Feb. 10, T&G-2). "There has also been a substantial number of reports of allergic reactions, some of which have caused life-threatening respiratory distress," FDA said. Such reactions are quinolone class-related; the incidence with Omniflox was apparently unusually high. "Consumers who have the medication are advised to consult their physician and return any unused portions of the product to the place of purchase," FDA said. "Similar antibiotics of [Omniflox'] class have not been reported to be associated with comparable numbers of serious adverse reactions." The withdrawal of Omniflox means the loss of one of two new anti-infectives with which Abbott hoped to maintain its long- established antibiotics business. Biaxin (clarithromycin), an azalide antibiotic, was approved three months before Omniflox, on Oct. 31. NDAs for both agents were filed in December 1989. Abbott held Omniflox up as an example of improved efficiency in drug development: the drug was discovered in-house and "required only 22 months" from IND to NDA ("The Pink Sheet" April 8, 1991, p. 9). Abbott was promoting Omniflox as "coming soon" in December at the American Society of Hospital Pharmacists mid-year meeting in New Orleans and also had run journal teaser ads. The company signed a copromotion agreement with ICI in September to add marketing muscle behind the antibiotic ("The Pink Sheet" Sept. 9, 1991, T&G- 1). Abbott's action is the first sudden withdrawal of a drug due to postmarketing adverse reaction reports since 1986 when Hoechst's antidepressant Merital was pulled from the market. In that case, the increased reports of severe hemolytic anemia were discovered overseas. In the same year, Burroughs-Wellcome's antidepressant Wellbutin was withdrawn when an unusual seizure rate was found in a Phase IV trial conducted by the company. Wellbutrin returned to the U.S. market in July 1989. In 1986, Johnson & Johnson's nonsteroidal anti-inflammatory drug Suprol was relabeled as second-line therapy in the U.S. following its withdrawal due to side effectsseen in the U.K. J&J eventually withdrew the product in the U.S. as well.