Eclampsia and pre-eclampsia
Michael S. Marsch, Janet M. Rennie, Phillipa A. Groves in Clinical Protocols in Labour, 2020
The signs and symptoms of pre-eclampsia are many and include: visual disturbance; flashing lights; headache; epigastric pain; raised blood pressure (BP); hyper-reflexia; clonus; changes in optic fundi; epigastric or liver edge tenderness; and oedema. BP should be recorded with the cuff at the level of the heart. The diastolic pressure is taken as abolition of heart sounds. Post-delivery the hydralazine should be reduced after 4 h by 1mg/h. If the BP rises during this reduction nifedipine 5-10 mg sublingually may be used as required to control BP. Urine output measurement and urinalysis should be performed hourly. BP measurements should be taken every 15 min using an automated blood pressure recorder and checked manually using a sphigmomanometer and stethoscope every hour. Intensive therapy unit charts should be filled in at least hourly. The hourly fluid intake, urine output and fluid balance, BP central venous pressure, oxygen saturation and blood results should all be recorded, filling in important events.
Write short notes on the mode of action of drugs that lower blood pressure
Nathaniel Knox Cartwright, Petros Carvounis in Short Answer Questions for the MRCOphth Part 1, 2018
Elevated blood pressure (BP) accelerates microvascular and macrovascular disease. Antihypertensive agents are widely prescribed. They include: β -blockers (e.g. atenolol): – the precise antihypertensive action of β -blockers is poorly understood – reduce cardiac output, alter baroreflex sensitivity and block peripheral adrenoreceptors – it is possible that their antihypertensive effect is central α -blockers (e.g. prazosin): – reduce BP by blocking post-synaptic α -receptors, causing vasodilatation calcium channel blockers (e.g. nifedipine): – act by blocking calcium influx through the slow transmembrane calcium channels – dihydropyridine calcium channel blockers such as nifedipine cause vasodilatation alone; non-dihydropyridine calcium channel blockers such as verapamil are also negative ionotropes angiotensin-converting enzyme (ACE) inhibitors (e.g. ramipril): – block the conversion of angiotensin I to angiotensin II – reduction in angiotensin II levels leads to reduced salt and water retention and vasodilatation – particularly useful in diabetic patients in whom they may protect against nephropathy angiotensin II antagonists (e.g. losartan): – used in those intolerant of ACE inhibitors, these drugs directly inhibit angiotensin II – actions are identical to ACE inhibitors nitrates (e.g. glyceryl trinitrate): – reduce blood pressure through a direct vasodilatating action on smooth muscle central-acting antihypertensives (e.g. methyldopa): – mode of action is uncertain.
Additional trials
Norman M Kaplan in Hypertension in the Elderly: Pocketbook, 1999
Two trials not included in the Blood Pressure Lowering Treatment Trialists’ Collaboration analysis because of methodological problems have been published, both from China. In the Shanghai Trial of Nifedipine in the Elderly (STONE) (Gong et al., 1996) the patients were entered sequentially and not randomly into the active (nifedipine) or placebo groups, thereby giving rise to possible bias. None the less, the data are quite consistent with the other trials in the elderly, showing significant reductions in stroke and overall mortality with nifedipine (15 deaths in 817 patients) compared to placebo (26 deaths in 815 patients).
The effects of nifedipine on respiratory mechanics investigated by theend-inflation occlusion method in the rat
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2017
Alessandro Rubini, Vincenzo Catena, Daniele del Monte, Gerardo Bosco
Context: Calcium channel blockers may theoretically exhibit relaxing effects not only on vascular smooth muscle but also on airway smooth muscle. Objective: To investigate possible effects of nifedipine on respiratory mechanics in the rat. Methods: Respiratory system mechanical parameters were measured by the end-inflation occlusion method in the rat in vivo before and after the intraperitoneal administration of nifedipine. Results: We found that nifedipine affects respiratory mechanics, inducing a reduction of airway resistance and of respiratory system elastance, probably because of a relaxing action on airway and parenchimal smooth muscle cells. Conclusion: Should these results be further confirmed by human investigations, a possible role of nifedipine in pharmacological respiratory system’s diseases treatment may be suggested.
Nifedipine and telmisartan for the treatment of hypertension: the TALENT study
Published in Expert Review of Cardiovascular Therapy, 2011
Giuseppe Derosa, Pamela Maffioli
A combination of two drugs as initial treatment in patients with a high or very high cardiovascular risk profile is recommended. Nifedipine extended release (GITS) is a calcium-channel antagonist known to be metabolically neutral, to mildly slow the development of atherosclerosis in hypertensive subjects and to significantly decrease cardiovascular risk in diabetic patients. Telmisartan is highly selective for the angiotensin receptor 1, it gives a greater improvement in glycemic and lipid control compared with irbesartan, and it proved its superiority in improving insulin sensitivity compared with eprosartan. The TALENT study was aimed to determine whether combining low-dose nifedipine GITS at and telmisartan reduced ambulatory and clinic blood pressure more than the two components in monotherapy in hypertensive patients at high cardiovascular risk. The study shows that combination treatment with nifedipine GITS and telmisartan provides a greater and earlier blood pressure reduction than the combination components in monotherapy.
Plateau hypoxia attenuates the metabolic activity of intestinal flora to enhance the bioavailability of nifedipine
Published in Drug Delivery, 2018
Juanhong Zhang, Yuyan Chen, Yuemei Sun, Rong Wang, Junmin Zhang, Zhengping Jia
Nifedipine is completely absorbed by the gastrointestinal tract and its pharmacokinetics and metabolism may be influenced by microorganisms. If gut microbes are involved in the metabolism of nifedipine, plateau hypoxia may regulate the bioavailability and the therapeutic effect of nifedipine by altering the metabolic activity of the gut microbiota. We herein demonstrated for the first time that gut flora is involved in the metabolism of nifedipine by in vitro experiments. In addition, based on the results of 16S rRNA analysis of feces in rats after acute plateau, we first confirmed that the plateau environment could cause changes in the number and composition of intestinal microbes. More importantly, these changes in flora could lead to a slower metabolic activity of nifedipine in the body after an acute plateau, resulting in increased bioavailability and therapeutic efficacy of nifedipine. Our research will provide basis and new ideas for changes in the fecal flora of human acutely entering the plateau, and contribute to rational drug use of nifedipine.
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