Dr. Abu Bakar Abdul Majeed
The Sun, June 13,1995
LOOKING AT THE CURRENT TREND IN human behaviour, especially in relation to men's over-indulgence in the redundant activity elegantly called smoking, a rethink on the subgroupings of Homo Sapiens appear to be in order.
For example, data from the World Health Organization (WHO) indicated that towards the end of the last decade, there were over a billion smokers.
In developed countries, a third of those above 15 years of age were smokers. This figure is unfortunately higher in developing countries where half of the adult population smoke. During the Ninth World Conference on Tobacco and Health in Paris last year, it was revealed that between 50-60% men and 2-10% women in the Asia Pacific region were smokers.
Closer to home, it is estimated that three million Malaysians above 15 years old are smokers, in which almost 85% of them are male.
Looking at these mammoth figures, and in view of the altered physiology of regular smokers, we have to accept the fact that these people, too, deserve a classification of their own. When cigarette smoke is inhaled, the smokers not only obtain a generous dose of nicotine, carbon monoxide, tar, hydrogen cyanide and ammonia, but their lungs also absorb a cocktail of over 4, 000 poisonous gaseous and particulate compounds.
The daily onslaught of these chemicals on the various body systems of smokers are bound to change their physiological properties. Thus, it is time to formalise tobaccophiles as a distinctly separate subgroup of Homo sapiens, perhaps Homo sapiens nicotinus.
Having said that, doctors, pharmacists and smokers beware! When prescribing, dispensing and using medications, a few special considerations need to be taken into account.
Some drugs may be incompatible with the act of smoking. Any one of the chemicals inhaled with cigarette smoke may enhance or attenuate the effects of the prescribed drugs. It appears that the primary impact of smoking on drug activity is through the effects of fat-soluble polycyclic or polynuclear aromatic hydrocarbons, which include the pyrenes, anthracenes and phenantrenes.
These chemicals enhance the activity of the liver oxidizing enzymes, leading to a more rapid inactivation of drugs. Other components of tobacco smoke that can further induce enzymatic activity are nicotine, cadmium and pesticide residues.
Some other substances such as carbon monoxide, hydrogen cyanide, acrolein and the various alkaloids may inhibit these enzymes. Indeed, studies on these incompatibility problems have revealed numerous interesting findings.
As most of us know, antibiotics are frequently prescribed for the treatment of infectious diseases. The antibiotic oxacillin is normally combined with the anti-ulcer drug omeprazole to treat peptic ulcers due to Helicobacter pylori.
Smoking has been shown to impede the effects of this combined therapy and patients have been found to be less likely to recover. Similarly, the actions of other anti-ulcer drugs such as ranitidine and cimetidine appear to be antagonised by smoking.
Thus, ulcer healing is delayed and relapse is more likely to happen, as smoking itself stimulates acid secretion.
Another group of drugs frequently used are oral contraceptives. Women need to be aware that smoking increases the risk of cardiovascular diseases associated with oral contraceptives use.
For example, one study has shown that combined smoking and oral contraceptive use contribute substantially to the number of heart attack cases occurring among American women aged between 35 to 44 years.
In fact, the American Food and Drug Administration requires that packages of oral contraceptives contain a printed leaflet: "Women who use oral contraceptives should not smoke".
In order to counter this type of incompatibilities, health care providers should regularly discuss smoking with their patients. Repeated discussions are valuable among both non-smokers who can be discouraged from starting to smoke, and smokers, who are more likely to quit if confronted repeatedly.
Despite the best efforts of the medical community, some young women will continue to smoke and use oral contraceptives at the same time. These women should be warned about the additional risks involved. Preferably, when prescribing oral contraceptives for women who will continue to smoke, health care providers should prescribe contraceptives providing low doses of estrogen and progestin.
Psychotropics or drugs acting on the brain have also been found to be incompatible with smoking. Although studies are somewhat contradictory in this area, smoking has been found to increase the rate of inactivation of some anti-anxiety drugs, such as diazepam(Valium). The net effect of this is decreased drowsiness. Patients will be less likely to sleep.
Drugs which are used as major tranquilisers are also susceptible to the effects of cigarette smoke. Smokers may require a higher dose in order to achieve the desirable effects.
The effect of smoking on the anti-asthmatic drug theophylline is one of the best documented clinical cases of drug vis-à-vis smoking incompatibilities. There is a 40% increase in the elimination of this particular drug in smokers compared to non-smokers. As a result, smokers may need their theophylline dose increased by 15-20% of that required by a non-smoking patient.
In conclusion, the combined effect of drug and smoking is still a grey area. For health-care providers, the factors of drug dosage and smoking will never be that easy. There are no such thing as known quantities or even known chemical activities when dealing with cigarette smoke. Tobacco contents, pesticide exposures and all the variables related to the physical act of smoking (degree of inhalation and size of cigarette) are unknown and inconsistent. Therefore, the best advice to patients undergoing therapy is still STOP SMOKING!
