Etanercept: therapeutic use in patients with rheumatoid arthritis.

Tumour necrosis factor (TNF) plays a central part in the pathophysiology of rheumatoid arthritis (RA). TNF initiates signal transduction by interacting with surface bound TNF receptors. Soluble tumour necrosis factor receptors (sTNFRs) act as natural inhibitors of TNF activity. Etanercept, recombinant p75 sTNFR:Fc fusion protein, has received approval from the US Food and Drug Administration for patients with RA and juvenile RA (JRA) who have failed treatment with at least one other drug. Etanercept has demonstrated excellent safety and efficacy in large scale, randomised, double blind, placebo controlled trials of patients with RA and JRA who are refractory to other disease modifying anti-rheumatic drugs. The therapeutic effects mediated by etanercept are rapid and sustained. Combining etanercept with methotrexate was found to be safe and more effective than treatment with methotrexate alone in the treatment of RA. These clinical findings demonstrate that etanercept can result in symptomatic improvement in patients with RA and JRA. Etanercept is an important new addition to the treatment of these diseases.

Etanercept therapy in rheumatoid arthritis. A randomized, controlled trial.

BACKGROUND: In a phase II study, etanercept (recombinant human tumor necrosis factor receptor [p75]:Fc fusion protein) safely produced rapid, dose-dependent improvement in rheumatoid arthritis over 3 months. OBJECTIVE: To confirm the benefit of etanercept therapy of longer duration and simplified dosing in patients with rheumatoid arthritis. DESIGN: Randomized, double-blind, placebo-controlled trial with blinded joint assessors. SETTING: 13 North American centers. PATIENTS: 234 patients with active rheumatoid arthritis who had an inadequate response to disease-modifying antirheumatic drugs. INTERVENTION: Twice-weekly subcutaneous injections of etanercept, 10 or 25 mg, or placebo for 6 months. MEASUREMENTS: The primary end points were 20% and 50% improvement in disease activity according to American College of Rheumatology (ACR) responses at 3 and 6 months. Other end points were 70% ACR responses at 3 and 6 months and other measures of disease activity at 3 and 6 months. RESULTS: Etanercept significantly reduced disease activity in a dose-related fashion. At 3 months, 62% of the patients receiving 25 mg of etanercept and 23% of the placebo recipients achieved 20% ACR response (P < 0.001). At 6 months, 59% of the 25-mg group and 11% of the placebo group achieved a 20% ACR response (P < 0.001); 40% and 5%, respectively, achieved a 50% ACR response (P < 0.01). The respective mean percentage reduction in the number of tender and swollen joints at 6 months was 56% and 47% in the 25-mg group and 6% and -7% in the placebo group (P < 0.05). Significantly more etanercept recipients achieved a 70% ACR response, minimal disease status (0 to 5 affected joints), and improved quality of life. Etanercept was well tolerated, with no dose-limiting toxic effects. CONCLUSIONS: Etanercept can safely provide rapid, significant, and sustained benefit in patients with active rheumatoid arthritis.

Warfarin-fluconazole. II. A metabolically based drug interaction: in vivo studies.

Consistent with expectations based on human in vitro microsomal experiments, administration of fluconazole (400 mg/day) for 6 days to six human volunteers significantly reduced the cytochrome P450 (P450)-dependent metabolic clearance of the warfarin enantiomers. In particular, P4502C9 catalyzed 6- and 7-hydroxylation of (S)-warfarin, the pathway primarily responsible for termination of warfarin's anticoagulant effect, was inhibited by approximately 70%. The change in (S)-warfarin pharmacokinetics caused by fluconazole dramatically increased the magnitude and duration of warfarin's hypoprothrombinemic effect. These observations indicate that co-administration of fluconazole and warfarin will result in a clinically significant metabolically based interaction The major P450-dependent, in vivo pathways of (R)-warfarin clearance were also strongly inhibited by fluconazole. 10-Hydroxylation, a metabolic pathway catalyzed exclusively by P4503A4, was inhibited by 45% whereas 6-, 7-, and 8-hydroxylations were inhibited by 61, 73, and 88%, respectively. The potent inhibition of the phenolic metabolites suggests that enzymes other than P4501A2 (weakly inhibited by fluconazole in vitro) are primarily responsible for the formation of these metabolites in vivo as predicted from in vitro kinetic studies. These data suggest that fluconazole can be expected to interact with any drug whose clearance is dominated by P450s 2C9, 3A4, and other as yet undefined isoforms. Overall, the results strongly support the hypothesis that metabolically based in vivo drug interactions may be predicted from human in vitro microsomal data.

Severe reversible neutropenia following treatment of prostate cancer with flutamide.

Flutamide was administered to a patient in conjunction with orchiectomy for stage D2 prostate cancer. Subsequently, profound neutropenia developed with a neutrophil count of 0.28 x 10(9)/l. Bone marrow aspirate showed granulocyte hypoplasia and maturation arrest consistent with drug induced injury. Neutrophil count returned to normal after discontinuation of flutamide and administration of a short course of granulocyte colony-stimulating factor. Other medications were continued with no effect on neutrophil count. The appearance of the bone marrow and the return of neutrophils after the discontinuation of flutamide indicate that flutamide may have contributed to neutropenia.