Dose response and length of action of nifedipine capsules and tablets in patients with essential hypertension: a randomised crossover study

Personalized medicine: the impact on chemistry

An effective strategy for personalized medicine requires a major conceptual change in the development and application of therapeutics. In this article, we argue that further advances in this field should be made with reference to another conceptual shift, that of network pharmacology. We examine the intersection of personalized medicine and network pharmacology to identify strategies for the development of personalized therapies that are fully informed by network pharmacology concepts. This provides a framework for discussion of the impact personalized medicine will have on chemistry in terms of drug discovery, formulation and delivery, the adaptations and changes in ideology required and the contribution chemistry is already making. New ways of conceptualizing chemistry's relationship with medicine will lead to new approaches to drug discovery and hold promise of delivering safer and more effective therapies.

Dose-response relationships with antihypertensive drugs

A variety of antihypertensive drugs have been introduced into clinical practice at excessively high dose. Examples include most thiazide diuretics, propranolol, oxprenolol, atenolol, methyldopa, hydralazine and captopril. These very high doses have usually resulted from studies in which doses have been increased at regular intervals until the desired antihypertensive effect has been achieved or until unacceptable adverse effects have resulted. Frequently the starting doses were too high and the intervals between dose adjustment too short. In many cases these large doses resulted in unnecessary adverse effects--the adverse biochemical effects of thiazide diuretics, nephrotic syndrome, taste disturbances and neutropenia with captopril, the lupus syndrome with hydralazine and the central nervous system effects of methyldopa. Parallel group design with single doses and sufficient statistical power to distinguish between the upper and lower ends of the antihypertensive dose-response relationship should replace the dose-escalating design.

Acute and sustained changes in sodium balance during nifedipine treatment in essential hypertension

PURPOSE

To assess the changes in sodium excretion and sodium balance after initiation of nifedipine treatment and after withdrawal of nifedipine.

PATIENTS

Eight patients with uncomplicated mild to moderate essential hypertension were entered in a single-blind, placebo-controlled study of 39 days' duration.

METHODS

Two 7-day periods while on a fixed sodium intake of 150 mmol/day approximately 3 weeks apart. After 4 days of a placebo and fixed sodium intake, patients were given nifedipine GITS (gastrointestinal therapeutic system) once a day and carefully studied for the following 4 days. Thereafter, patients continued to receive nifedipine GITS, and approximately 3 weeks later they were studied again for a week while on a fixed sodium intake. Nifedipine administration was stopped and changes occurring after withdrawal were studied.

RESULTS

Nifedipine caused a significant increase in sodium excretion with a cumulative loss of sodium of 38 mmol per subject within the first 4 days of treatment. The withdrawal of nifedipine treatment caused a significant decrease in sodium excretion and a cumulative retention of sodium of 42 mmol per subject within the first 4 days of withdrawal.

CONCLUSION

Nifedipine causes an acute and a sustained reduction in sodium balance in patients with essential hypertension. This prolonged effect may contribute to the mechanism whereby nifedipine lowers blood pressure.

Nifedipine and hypertension: roles of vasodilation and sodium balance

Nifedipine reduces blood pressure predominantly by reducing systemic vascular resistance due to a direct vasodilating action on the arterioles. This peripheral vasodilation appears greater the more severe the hypertension. Nifedipine also causes a long-term loss of sodium, which may be an additive mechanism for the blood pressure fall. In patients who are not controlled on nifedipine alone, studies have demonstrated an additive effect of beta blockers and converting-enzyme inhibitors on blood pressure. There is controversy about whether diuretics have an additive effect on blood pressure in patients already on nifedipine.

Determinants of antihypertensive response to calcium antagonists in systemic hypertension

Calcium antagonists are an important group of drugs in the treatment of systemic hypertension. Examination of the factors that determine the magnitude of antihypertensive response to calcium antagonists is of interest for clinical and basic pathophysiologic reasons. Possible factors influencing response include drug dose, plasma drug concentration, plasma renin activity, baseline blood pressure, nonionized calcium in blood and inside vascular smooth muscle cells, patient age and patient race. Published studies have examined the determinants of antihypertensive response. The striking fact about many of these studies is that they fail to control for other possible factors that might influence response. This article reviews the methods used and the results of 23 different studies that examined the determinants of response to calcium antagonists. Possible relationships between plasma renin activity, intra- and extracellular calcium levels, and the antihypertensive response, are of interest from a pathophysiologic point of view. From a clinician's standpoint, the only determinants that matter are the dose of the drug and the degree of elevation of the blood pressure. In this regard, calcium channel blocking drugs are no different from other drugs that act by peripheral vasodilation.