Drugs for Allergies

Numerous drugs can be used to treat allergics which play no part in altering the underlying cause of the condition. Thus tranquillizers may be prescribed if the patient is distressed; skin rashes may be treated with creams, arthritis with pain-killers and stomach upsets with various remedies aimed at slowing down, speeding up or altering the acidity of the alimentary tract.

These are all what we call ‘symptomatic’ treatments. That is, they are geared solely to suppressing the symptoms and are not a cure. Basically, this sort of drug therapy assumes less and less importance as the detection of specific allergens and their avoidance is increased.

There are, however, three classes of drugs intended to alter the status of allergic disease and so diminish or eradicate symptoms. These are a) antihistamines, b) steroids and c) mast cell stabilizers.

ANTIHISTAMINES
Antihistamines are possibly the best known and most widely used of all allergy remedies.

Histamine is released when mast cells break down. It is responsible for the redness, swelling and itching typical of allergic rashes. It also causes tissue swelling as in bronchospasm and pain as in migraine.

Antihistamines are generally very safe; any inherent problems stem mainly from their side-effect of drowsiness. Patients vary in their response. Newer preparations such as terfenadine (Triludan) and astemizloe (Hismanal) have attempted to eradicate the drowsiness and have been fairly successful. Other preparations seek to exploit it and promethazine (Pheneragan) and trimeprazine (Vallergan) are used as sedatives for children.

Other brand-names you may encounter are: Tevegil, Optimine and Fabahistin.

Antihistamines may provide helpful short-term relief for allergy sufferers. One important point, however: they will mask the effect of skin testing and should be discontinued several days before undergoing any such tests.

STEROIDS
Mention the word steroids and most people now recoil in horror. Yet, apart from antibiotics, probably no class of drug has saved more lives. Why all the fuss? The side-effects can be pretty awful – fat deposits (‘moon face’), infertility, loss of skin tissue and osteoporosis (brittle bones) – but they usually only develop when the drugs have been taken long term.

The fact is, steroids may produce dramatic recoveries but, again, no cure. When they are stopped the illness often roars back into view, sometimes worst than before (this is called the ‘rebound’ phenomenon).

A one-off dose of Depomedrone or Kenalog can prompt wonderful relief from severe and debilitating hay fever or an unbearable rash, for as long as three weeks at a stretch (though usually for about 10 days). Often the use of these drugs amounts to practical logistics – say where the patient is a busy and committed business person who cannot for some reason follow a more fundamental plan of avoidance and desensitization as described elsewhere in desensitization as described elsewhere in this book. Naturally, such ‘emergencies’ should not be repeated often.

The common steroid you will encounter is prednisolone. Other names for it include ‘cort’, referring to the origin of these hormones (the adrenal cortex – the outer layer of the adrenal gland).

It is often forgotten that the contraceptive pill is steroidal (oestrogen and progesterone). Cholesterol is a distant relative.  

MAST CELL STABILIZERS
The breakthrough drug in this class was sodium cromoglycate (SCG). First used in asthma (as Intal), it was found to be an excellent prophylacitic since it prevented the breakdown of mast cells and the consequent release of histamine. It therefore operates one step ahead of antihistamines. Providing the patient takes it regularly it can diminish the frequency and intensity of bronchospasm, though once the symptom comes on it is useless for relief.

It was logical to try it for rhinitis and a nasal insufflation called Rhynacrom was developed. There were high hopes that this drug might be of benefit for food allergics and Fisons (the license holders) brought Nalcrom onto the marker. Unfortunately, it was a failure. It loses its effect very quickly and has little or no long-term therapeutic benefit. Nevertheless. It does work short-term and can be of great benefit to patients who need to attend special occasion dinners such as weddings and anniversaries, or even to use it before a sinful ‘blow-out’ when the restrictions of structured dieting become too much. Take 3 to 6 capsules on the day in question and, to be quite safe, on the following day, too.

Ketotifen (Zantac) is a newer mast cell stabilizer. Its long-term efficacy is uncertain. It has antihistamine properties and therefore causes drowsiness. Finally, of course, all drugs can be allergenic. They are all xenobiotics. Just because they are used to treat allergy does not mean they might not be overload culprits themselves.