In Nigeria, cost of drugs can account for up to sixty percent (60%) of health expenditure (Salako, 1992), in contrast to only about 10-20% in developed nations. The reason is that until recently, health was heavily subsidized and even free in some parts of the country where the party in power claimed to pursue a welfarist agenda. However, a careful scrutiny of the health budget will show that not all the drugs need to be purchased and many of those that are purchased do not necessarily give the users any substantive value for their money. Part of the problem is the intense promotional activities of marketers of pharmaceuticals, which are often more concerned with boosting sales of their drugs than promoting genuine scientific knowledge (Lexchin, 1987).

Consequently, health care professionals unwittingly rely on the information on drugs provided in the advertisement by marketing companies rather than on the scientific literature (Avorn et at, 1989; Lexchin, 1992). Advertisement– induced knowledge has been implicated in incorrect use of medicinal drugs in many developing countries (Dikshit and Dikshit, 1996) as a result of inadequate prescription guides. There is some evidence (Assad and Mirza, 1999, Okoro and Davies, 2000) that providing accurate and comprehensive drug information is not a priority for many marketing companies doing business in third world countries. Indeed, the United States Office of Technology Assessment estimated that up to two-thirds of medicines sold in developing countries by Multinational Drug Companies have probably been packaged with incomplete or misleading prescription guides (Frankel, 1993), thus precipitating irrational use of drugs as well as increasing the cost of health care.

In order to minimise this problem, the Nigerian Government organised in 1994 a workshop for senior medical educators and teachers of pharmacology in the country. At the workshop, the participants were asked to draw up a programme that would incorporate into the curriculum, the teaching of essential drug concepts with a view to inculcating the principle and practice of rational drug use as well as economic prescription model in future doctors and pharmacists.

In 1998, a pharmaceutical company also launched an educational programme, ostensibly as part of its contribution to the rational drug use programme. The educational programme was in the form of an essay competition and was designed specifically for penultimate and final year medical and pharmacy students as well as intern doctors and pharmacists. The objective of the programme, as stated by the company, was to draw attention to the peculiarities of hypertension in blacks that should be taken into consideration in the choice of anti-hypertensive drugs for Nigerians. For this reason, the company listed two essay topics for the 1999 competition for two categories of competitors, namely (1) medical interns and students and (2) intern pharmacists and pharmacy students. The essay topics were: (a) Quality of life in hypertension: Evaluation of therapeutic alternatives, for medical interns and students. (b) Pharmaco-economics and hypertension: Implications for the black hypertensives, for intern pharmacists and pharmacy students.

In the advertisement announcing the 1999 essay competition (fig. 1) the sponsors of this educational programme who were also the makers and distributors of a fixed drug combination of prazosin O.5mg and 0.25mg polythiazide per tablet indicated conspicuously and for effect, that this medication is the “antihypertensive tailored for the black patient” (fig. 1).

Background Pharmacology of Prazosin

Prazosin is an anti-hypertensive drug available as a single formulation and prazosin as a fixed combination which contains prazosin and polythiazide in doses as earlier indicated (fig. 1). Generally, prazosin is a highly selective aladrenergic antagonist that lowers blood pressure on the basis of its blockade of this receptor type at arterial smooth muscle. Its neutral effect on blood lipids and glucose metabolism reported in many studies (Alderman and Madhaven, 1981; Murphy et at, 1982) initially enhanced its popularity and preference over thiazides because of safety concerns. At that time, it was believed that the adverse effects of thiazides on electrolytes, particularly hypokalaemia, were in some way linked to the lack of reduction in cardiac mortality in hypertensive patients treated with thiazides. However, this problem has now been laid to rest because subsequent studies (Ajayi et al, 1989; Salako et al, 1998; Matterson et at, 1993; Flack and Cushman, 1996; Kapuku et al, 1998) in many parts of the world, including Nigeria, have shown that when correctly used, thiazides effectively lower blood pressure without any clinically relevant electrolyte and metabolic consequences.

Furthermore, while prazosin (single formulation) is made available in many countries by the Marketers referred to - in fig. 1, prazosin is only available and marketed as a fixed drug combination in Nigeria (Mims, 1983 - 1989; 1999; BNF, 1991). The maximum recommended daily dose for the treatment of hypertension is 16 tablets, i.e. 8 mg prazosin combined with 4 mg polythiazide (Ibid). On the other hand, polythiazide on its own is not marketed in Nigeria but is available to prescribers in the UK (BNF, 1991). The recommended daily dose for polythiazide in the treatment of hypertension is 1-4 mg, although prescribers are advised to start with as low as 0.5 mg which is often sufficient to control blood pressure in most cases (Ibid).