Pharmacology Update

The Latest Information on New Drugs and New Indications

Two new drugs for rheumatoid arthritis (ra) are now available and will enter the market with hefty price tags. Leflunomide (Arava-Hoechst), an oral RA medication, will cost $3000 per year while etanercept (Enbrel-Immunex), a parenteral tumor necrosis factor inhibitor, is priced at more than $10,000 per year. Another anti-TNF drug, infliximab (Remicade-Centocor), currently approved for treating Crohn’s disease, is being studied for use in RA in combination with methotrexate, at a cost of up to $40,000 per year. (Centocor’s plans hit a bump in the road recently when they were forced to issue a Dear Doctor letter regarding severe side effects of infliximab in patients retreated with the drug several years after their initial treatment.) In the suddenly crowded RA market, Immunex hopes to hit the ground running with plans to spend $100 million on marketing of etanercept and is already filing an application with the FDA for the indication of juvenile arthritis.

Statins may benefit all CAD patients, regardless of their baseline cholesterol levels. The LIPID study from Australia and New Zealand randomized more than 9000 patients with recent MIs or unstable angina to placebo or pravastatin (N Engl J Med 1998;339:1349-1357). Over a mean follow-up of six years, the pravastatin group had significantly lower rates of MI, CAD-related deaths, and overall mortality. The study group included patients with baseline cholesterol levels from the mid 150s to more than 270, all of whom benefited from treatment.

The number of approved angiotensin II receptor blockers (ARBs) has grown to six with the November FDA approval of telmisartan (Micardis-Boehinger). It joins losartan, valsartan, irbesartan, and candesartan as actively marketed drugs, while eprosartan and tasosartan, although approved, have not yet been launched. These drugs appear to be useful and safe anti-hypertensive agents, but now each is looking for a niche in this competitive market. Boehinger claims that telmisartan has the longest half-life of the group, making it a "true" once-daily drug.

Treating pneumoccocus is becoming difficult as more and more isolates are proving multidrug resistant. In a recent survey from more than 30 hospitals in the United States and Canada (Clin Infect Dis 1998;27:764-780), 16% of pneumococci were fully resistant to penicillin, and another 28% were intermediately sensitive. First- and second-generation cephalosporins fared a little better; for example, 38% of isolates were resistant to cefaclor. TMP/SMX was ineffective on 20% of isolates and resistance was also seen in macrolides, such as erythromycin, up to 14% of the time. Higher doses of some of these drugs may achieve effective MICs, and antipenicillinase drugs, such as augmentin, seem to be effective. The new quinolones may prove useful in this role as well. Culturing whenever possible and watching sensitivities to pneumococcus, especially in serious infections, is essential.

The American Academy of Pediatrics has added another vaccine to its recommended list for children. The recently approved rotavirus vaccine is effective in preventing diarrheal disease caused by this common virus, which is responsible for 50,000 hospitalizations each year. The rotavirus vaccine is given at 2, 4, and 6 months of age.

From the Future File—Promising work is being done on several unique approaches to common diseases. Researchers at Duke University have developed a selectively permeable microcapsule made from a polysaccharide hydrogel in which they have implanted dog islet cells. When implanted in the abdomens of rats, the cells remained viable, were not rejected, and improved glycemic control for about a week, at which time the effect was lost. Pennsylvania-based pharmaceutical company Magainin is testing pexigan, a unique broadspectrum antibiotic that is derived from the skin secretions of the African clawed frog. The antimicrobial peptide is being tested as a topical agent and appears to be active against more than 3000 aerobic and anaerobic bacteria, including the pathogens found in diabetic foot ulcers. Finally, promising work is being done on spinal cord injuries. Animal models from labs across the country are showing transmission of nerve impulses across repaired sections of severed spinal cords. Purdue University researchers are using polyethylene glycol to fuse surgically severed spinal cords while researchers at Yale University are using transplanted Schwann cells and olfactory ensheathing cells in damaged spinal cords.

Drug costs continue to escalate at a rate of 12-15% each year representing the fastest growing segment of the healthcare economy and straining the coffers of managed care organizations (MCOs). And as health care executives look to the future, there is no relief in sight. The FDA has streamlined many of it’s processes in recent years, resulting in faster approval times and doubling the number of new drugs approved each year compared to just five years ago. Newer drug technologies may be more efficacious, safer, or easier to take than the older medications they are replacing, but the cost is often 10-100 times the cost of the older medication. Increased use is also driving the increase in drug costs. New medications are often approved for completely new indications, creating demand for drugs where there was none before. More than $700 million of direct-to-consumer advertising this year has also increased demand as has the $3 billion spent by the pharmaceutical industry on marketing. The result is that not only are medications more costly, but more people are taking a greater number of medications than ever before. It is inevitable that consumers will start feeling the pinch as MCOs pass on the increased costs in the form of higher premiums, reduced coverage, or both.