Pharmaceutical Benefits Scheme
Certain medications listed on the PBS are available only for specific therapeutic indications or to patients meeting specific criteria where the PBAC has deemed that the cost-benefit analysis is favourable only in those indications/patients. These are noted as "restricted benefits" on the Schedule. Medicare Australia places the onus of policing restricted benefits on the prescribers themselves and the pharmacists dispensing (unless the listing is also 'Authority Required'). For example, the COX-2 inhibitor celecoxib is listed on the PBS as a restricted benefit for the symptomatic treatment of osteoarthritis and rheumatoid arthritis. Prescribers using celecoxib for other indications are expected to indicate "non-PBS" on the prescription, and/or the pharmacist dispensing the celecoxib should charge the patient the full cost.
Flutamide
Flutamide has been found to be equal to slightly more potent than cyproterone acetate and substantially more potent than spironolactone as an antiandrogen in bioassays. This is in spite of the fact that hydroxyflutamide has on the order of 10-fold lower affinity for the AR relative to cyproterone acetate. Hydroxyflutamide shows about 2- to 4-fold lower affinity for the rat and human AR than does bicalutamide. In addition, whereas bicalutamide has an elimination half-life of around 6 days, hydroxyflutamide has an elimination half-life of only 8 to 10 hours, a roughly 17-fold difference. In accordance, at dosages of 50 mg/day bicalutamide and 750 mg/day flutamide (a 15-fold difference), circulating levels of flutamide at steady-state have been found to be approximately 7.5-fold lower than those of bicalutamide. Moreover, whereas flutamide at this dosage has been found to produce a 75% reduction in prostate-specific antigen levels in men with prostate cancer, a fall of 90% has been demonstrated with this dosage of bicalutamide. In accordance, 50 mg/day bicalutamide has been found to possess equivalent or superior effectiveness to 750 mg/day flutamide in a large clinical trial for prostate cancer. Also, bicalutamide has been shown to be 5-fold more potent than flutamide in rats and 50-fold more potent than flutamide in dogs. Taken together, flutamide appears to be a considerably less potent and efficacious antiandrogen than is bicalutamide.