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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 cost-effectiveness 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 cross-sectional evaluation of blood pressure (BP) control in a hypertension clinic was undertaken among 150 Nigerian patients aged 61±12 years (55% females), with a duration of treatment on a particular drug class or combination of 9±3 months. The initial blood pressure was 176±20/108±11 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%), P<0.0001, and ACE-inhibitors (ACEIs) (24%), P<0.0001, but a slight reduction in the use of methyldopa, and fixed drug combinations (P<0.01) compared to the previous study. The fall in systolic blood pressure on D (r=0.65, P<0.001) or CCB (r=0.48, P<0.02) was significantly correlated with the initial systolic blood pressure, but not age. More patients achieved normotension BP<140/90 mmHg on CCB monotherapy (71%), than D monotherapy (56%). Combination therapy with ACEIs+D or methyldopa+thiazides normalized BP in 63 and 68%, respectively. Pulse pressure, a surrogate marker for cardiovascular complications and mortality in essential hypertension, was significantly reduced (P<0.01) equally by all treatments, with 95% confidence intervals ranging from −28 to −1 mmHg. However, hypertensive-diabetic (HT-DM) patients (n=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 BP<130/85 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 cost-effective 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.

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Adigun, A., Ishola, D., Akintomide, A. et al. 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. J Hum Hypertens 17, 277–285 (2003). https://doi.org/10.1038/sj.jhh.1001538

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