Shifting trends in the pharmacologic treatment of hypertension in a Nigerian tertiary hospital: a real-world evaluation of the efficacy, safety, rationality and pharmaco-economics of old and newer antihypertensive drugs

Abstract

The current prescription patterns for essential hypertension and the efficacy, safety, tolerability and costeffectiveness of the newer antihypertensive drugs were evaluated in Nigerian patients. The findings were compared with that of a previous study conducted in the same tertiary hospital 10 years earlier. A crosssectional evaluation of blood pressure (BP) control in a hypertension clinic was undertaken among 150 Nigerian patients aged 61712 years (55% females), with a duration of treatment on a particular drug class or combination of 973 months. The initial blood pressure was 176720/108711 mmHg and 22% of the patient had concurrent diabetes mellitus. Thiazide diuretics (D) alone or in combination remained the most commonly prescribed drugs in 56% of all patients. There were significant increases in the prescriptions of calcium channel blockers (CCBs) (51%), Po0.0001, and ACEinhibitors (ACEIs) (24%), Po0.0001, but a slight reduction in the use of methyldopa, and fixed drug combinations (Po0.01) compared to the previous study. The fall in systolic blood pressure on D (r ¼ 0.65, Po0.001) or CCB (r ¼ 0.48, Po0.02) was significantly correlated with the initial systolic blood pressure, but not age. More patients achieved normotension BPo140/90 mmHg on CCB monotherapy (71%), than D monotherapy (56%). Combination therapy with ACEIs+D or methyldopa+thia-zides normalized BP in 63 and 68%, respectively. Pulse pressure, a surrogate marker for cardiovascular complications and mortality in essential hypertension, was significantly reduced (Po0.01) equally by all treatments, with 95% confidence intervals ranging from À28 to À1 mmHg. However, hypertensive-diabetic (HT-DM) patients (n ¼ 33) exhibited no significant change in pulse pressure in response to treatment. Adverse drug reactions that occurred in 11% were impotence or postural dizziness with D, headache and pitting oedema with CCB, and dry cough with ACEI. Pharmaco-economic comparison of the drug classes revealed that for every US dollar ($) spent per month, the percentage of treated patients attaining normotension was 18.6 for D, 4.73 for CCB, 3.5 for ACEI+D and 13.6 for methyldopa+thiazides. A combination of ACEI+CCB or D was the preferred treatment for hypertensive-diabetic Nigerians, but only 24% attained a BPo130/85 mmHg. These results demonstrate a shift in trend to a more rational and efficacious treatment of hypertension over a 10 year period. This may be associated, at least in part, with the intensive and continuous education of the prescribers in rational drug use and the introduction of a hospital formulary. Methyldopa is still a highly efficacious and costeffective drug in this population. Black HT-DM Africans still constitute a subgroup who not only require more and costlier antihypertensive drugs, but whose BP control is suboptimal, and exhibit a poor therapeutic response to other risk factors (pulse pressure) that constitute a continuing risk for cardiovascular mortality.

Prescription pattern of anti-hypertensive drugs in a tertiary health institution in Nigeria

“…The choice of diuretic as the first line antihypertensive drug is consistent with other reports from Nigeria, 10,13,14 and in compliance with the current national 15 and JNC VII guidelines. 8 However, contrary to the traditional recommendations in most guidelines including the report of Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT), 16 calcium channel blocker was found to lower blood pressures more than diuretic when both were used as monotherapy.…”

Antihypertensive pharmacotherapy in a developing economy: pattern, acquisition costs and conformity to international guidelines in a tertiary-care setting

“…7,8 The observed trend regarding CCBs predominating as preferred drug overall is similar to reports from other hospitals with a primarily black population. 5 The low rate of normotension achieved by our patients on CCB monotherapy compared with other studies could be partially ascribed to a myriad of generic forms of nifedipine available in the market, the standard and efficacy of which cannot be guaranteed. Although diuretics were not commonly prescribed as first line monotherapy, the percentage of patients with controlled hypertension was highest in this group and also in the group with diureticbased regimen.…”

“…There is a favourable disposition to combination therapy in recent years particularly in patients with more difficult to control BP (often encountered in tertiary or referral settings). 5 There is rational justification for such therapy because the multifactorial nature of hypertension is addressed, BP control and achievement of target BP tends to be better, and the risk of side effects owing to use of maximal doses of monotherapeutic agents is reduced. Furthermore, hypertension in black people runs an aggressive course and control is achieved with multiple drug therapy rather than monotherapy.…”

“…12 The degree of control in our study is similar to reports from another tertiary centre in Nigeria. 5 The BP control is however still unacceptably low, and improvements in BP control are desirable to reduce CVD morbidity and mortality in our centre.…”

“…What is known about this topic K Recent hypertension guidelines advocate stricter BP control to minimize cardiovascular morbidity and mortality 4,5 K The use of combination therapy and consideration of comorbidities in choosing antihypertensive therapy are emphasized by these guidelines 4,5 K In developing countries, acquisition cost of drugs is an important determinant of drug compliance and thus adequate BP control 5 What this study adds K Using our tertiary referral centre as an example, BP control in black hypertensives at high risk of cardiovascular disease in subSaharan Africa remains suboptimal K Combination therapy is increasingly used in this cohort, but diuretic-based therapies, which are the most cost effective in our setting, are still underutilized K Acquisition cost of brand name ACEIs and CCB is prohibitively high for our patients, and we re-advocate the use of equally effective, but cheaper generic forms of these drugs Abbreviations: ACEI, angiotensin-converting enzyme inhibitor; BP, blood pressure; CCB, calcium channel blocker.…”