How Come We Can't Cure The Cold?

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Indeed, the viral attack is practically over within the first couple of days of a cold, often before you realize that anything is wrong. To be effective, an antiviral cold drug would have to be taken as soon as you suspect you might be coming down with something. That's a tall order but not impossible. In the mid-1990s the German drug company Boehringer-Ingelheim developed an antiviral molecule, dubbed BIRR 4, that proved in clinical trials to significantly shorten most colds triggered by rhinoviruses and lessen their severity. The product worked by mimicking those molecular footholds used by rhinoviruses to gain entry into human cells. Spraying the nasal passages every few hours on the first day of a cold essentially fooled the virus into leaving the cells alone.

Sounds like a blockbuster drug, right? Wrong. Here's where those pesky business considerations come in. Once Boehringer's executives started doing the math, they quickly realized that BIRR 4 was not commercially viable. Its modest therapeutic effects, combined with the need to provide the drug so early in the infection process, severely limited its marketability. Two and a half years ago, Boehringer dropped further development of BIRR 4.

Another antiviral drug, called pleconaril, had the rug pulled out from under it last March when the U.S. Food and Drug Administration declined to approve it, citing concerns that pleconaril might interfere with the effectiveness of oral contraceptives and other drugs. To combat that problem, Viropharma, the biotech company that developed pleconaril, decided to reformulate the pill, turning it into a nasal spray, thereby lowering its dose and the chance that it might interfere with other drugs. Viropharma is now looking for another pharmaceutical company to help defray the costs of testing the new formula.

Of course, even if an effective antiviral drug is eventually developed, that takes care of only part of the problem. "You have to do more than just stop the virus," says Dr. Jack Gwaltney of the University of Virginia School of Medicine in Charlottesville. "You need to block these inflammatory processes too." Intriguingly, Gwaltney, who has studied the common cold for more than 40 years, has shown that although it's easy to become infected with a cold virus, about 25% of those who get infected suffer few if any symptoms. For whatever reason, their bodies do not go overboard fending off a viral attack. That suggests to him that you ought to be able to stop the virus and damp down the immune system without causing any major side effects and that any cure has to consist of a combination of drugs.

Gwaltney's favorite combo is a curious mix of high-and low-tech treatments: a quick squirt into the nose of the biotech drug interferon, followed by two over-the-counter pills--an anti-inflammatory like ibuprofen (such as Advil or Motrin) and a so-called first-generation antihistamine like chlorpheniramine (such as Chlor-Trimeton). The interferon primes the immune system to unleash its antiviral defenses while the ibuprofen and the chlorpheniramine keep the inflammatory processes under control.