A Cure for the Common Cold

What about a cure for the common cold ?

Over the last ten years we have learned a great amount about the structure of some of the common cold viruses and how they attack the lining of the nose. The rhinovirus which causes 30-40% of all infections has been studied in most detail and we now know that the virus attaches to the ICAM receptor (intercellular adhesion molecule, a type of glue molecule which holds cells together) before gaining entry to the nasal cells. The virus has many "pockets" or canyons" on its surface which attach to the ICAM receptor. Some new medications, such as PLECONARIL, are based on the structure of the ICAM receptor and they stick to the "canyon" receptors on the virus and prevent it from attaching to ICAM receptor on the nasal cells. This method of preventing the virus from entering the cell works well in the test tube where the concentration of medication can be maintained but does not work very well in the nose where the ICAM medication is rapidly cleared from the nose.

Unfortunately the USA regulators turned down an application for pleconaril to be registered as a medicine in 2002 because it interfered with the actions of the contraceptive pill. PLECONARIL may not be licensed as a treatment for common cold but it may still have a future as a treatment for more serious illnesses such as viral meningitis.

There is also some interest in developing a PLECONARIL nasal spray as a treatment for common colds, as this may overcome some of the problems associated with PLECONARIL tablets.

There may never be a cure for the common cold!

It is very unlikely that we are going to see a cure for the common cold because of the following problems-

• Common cold is not a single disease but a syndrome of symptoms caused by many different viruses. Defeating smallpox with a single vaccine was a relatively easy task compared to developing multiple vaccines for common cold

• By the time you know you have a cold it is probably too late to treat, as antivirals need to be taken 24-48 hours after onset of symptoms

• Any new medications must be extremely safe as they will be widely used

• Any minor side effects will not be tolerated for treatment of colds

• If the medication is really effective it will be reserved for hospital use to treat life-threatening infections. If the medicine is used widely the viruses will quickly evolve resistance in the same way bacteria have overcome antibiotics.

Golden age for common cold

We are living in a golden age for respiratory viruses such as common cold and influenza. As our cities grow more and more crowded the provide an ideal environment for the viruses to jump from one nose to another with an almost limitless supply of new noses to infect.

The density of population in cities and rapid tansport also make us at reisk from new deadly viris infections such as Severe acute respiratory syndrome (SARS) and new deadly strains of virus.