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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing recognition of the importance of calcium in the pathogenesis of cardiovascular disease has stimulated research into the use of calcium channel blocking agents for treatment of a variety of cardiovascular diseases. The favorable efficacy and tolerability profiles of these agents make them attractive therapeutic modalities. Clinical applications of calcium channel blockers parallel their tissue selectivity. In contrast to verapamil and diltiazem, which are roughly equipotent in their actions on the heart and vascular smooth muscle, the dihydropyridine calcium channel blockers are a group of potent peripheral vasodilator agents that exert minimal electrophysiologic effects on cardiac nodal or conduction tissue. As the first dihydropyridine available for use in the United States, nifedipine controls angina and hypertension with minimal depression of cardiac function. Additional members of this group of calcium channel blockers have been studied for a variety of indications for which they may offer advantages over current therapy. Once or twice daily dosage possible with nitrendipine and nisoldipine offers a convenient administration schedule, which encourages patient compliance in long-term therapy of hypertension. The coronary vasodilating properties of nisoldipine have led to the investigation of this agent for use in angina. Selectivity for the cerebrovascular bed makes nimodipine potentially useful in the treatment of subarachnoid hemorrhage, migraine headache, dementia, and stroke. In general, the dihydropyridine calcium channel blockers are usually well tolerated, with headache, facial flushing, palpitations, edema, nausea, anorexia, and dizziness being the more common adverse effects.
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PMID:Differential effects of 1,4-dihydropyridine calcium channel blockers: therapeutic implications. 332 59

Computed tomographic (CT) findings of cerebral and cerebellar calcification are described in three American adults with raised serum lead levels and known exposure to lead for 30 or more years. Calcification patterns were punctiform, curvilinear, speck-like, and diffuse and were found in the subcortical area, basal ganglia, vermis, and cerebellum. Admission serum lead levels ranged from 54 to 72 micrograms/dl (normal, 0-30 micrograms/dl). Nonspecific neurologic manifestations consisted of dementia, diminished visual acuity, peripheral neuropathy, syncope, dizziness, nystagmus, easy fatigue, and back pain. Two patients developed chronic renal disease and hypertension; in both cases, serum parathormone was elevated. Blood, calcium, and phosphorus were normal in all three. No other structural abnormalities were observed with CT. Although the pathophysiologic mechanism of these findings remains poorly understood, it is suggested that chronic lead exposure should be included in the differential diagnosis of unexplained intracranial calcifications in adults.
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PMID:Intracranial calcification in adults with chronic lead exposure. 348 74

Excessive accumulation of intracellular calcium in Duchenne muscular dystrophy (DMD) may be a necessary step in the process that causes muscle damage in this disease. Because of this possibility, a controlled trial of the calcium channel blocking agent nifedipine was undertaken. One hundred and five patients were randomized and treated in a double-blind manner for 18 months. Muscle strength, contractures, functional ability, cardiopulmonary changes, and laboratory data were monitored. The dose of nifedipine was 0.75-1 mg/kg/day in the first 6 months and 1.5-2 mg/kg/day for the next 12 months. Satisfactory blood levels of nifedipine were attained. The study had a power greater than 0.99 to detect a slowing of the illness to 25% of its original rate of progression. No significant improvement was demonstrated in the treated group. One or more of the frequent mild side effects of flushing, dizziness, and leg edema, often associated with the use of nifedipine in adults, occurred transiently in approximately one-half of the patients in the nifedipine group and in 21% of the placebo group. Four patients died, two on nifedipine and two on placebo. This study demonstrates that nifedipine is safe to administer in children, but that it is without beneficial effect on the course of DMD.
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PMID:Clinical investigation in Duchenne dystrophy. VI. Double-blind controlled trial of nifedipine. 355 Apr 55

Two studies with healthy volunteers were carried out to correlate safety with pharmacokinetics of the calcium antagonistic drug N-(3,3-diphenylpropyl)-(1-phenylethyl)-amine (fendiline, Sensit) after single and multiple oral doses. In the first study single doses of 200, 400, 600, 800, 1000, and 1200 mg of fendiline hydrochloride were administered to 6 subjects per dose level. 3 additional subjects per dose level received placebo. No significant objective or subjective effects were noted in the dose range studied. The pharmacokinetic analysis revealed that doses higher than 800 mg were absorbed incompletely. In the second study initially 400 mg twice daily was given to 9 subjects. 3 additional subjects received placebo. Due to subjective intolerability (trembling, dizziness) after 5 days, the dose was reduced stepwise to 2 X 200 mg and was then continued for another 19 days. The pharmacokinetic evaluation revealed manifold interindividual differences in plasma levels for maximal concentrations (9-170 ng/ml) as well as for minimal concentrations (4-96 ng/ml). The absorption profile in both studies has linear and nonlinear components. Maximal plasma levels were reached after about 4 h. Terminal elimination half-lives were about 20 h.
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PMID:Tolerance and pharmacokinetics of oral fendiline. 356 58

The effects of bepridil, a calcium antagonist with a half-life of approximately 42 hr, were assessed in a double-blind, randomized, placebo-controlled crossover trial. Forty-four patients (39 men, five women) with exercise-induced angina pectoris and ST segment depression with exercise testing (modified Bruce protocol) were studied. Compared with placebo bepridil (400 mg daily) increased total exercise time, time to onset of angina, time to 1 mm of ST segment depression, time to 2 mm of ST segment depression, and total work achieved (all p less than or equal to .001). Both frequency of angina and nitroglycerin consumption decreased during the bepridil compared with the placebo period (p = .02 and .03, respectively). Minor side effects were noted during both the bepridil and placebo phases. Four patients experienced side effects that limited therapy (dizziness in three and abnormal results of liver function tests in one) and one patient died during the bepridil phase. This study suggests that bepridil, 400 mg daily, is effective for the treatment of exercise-induced myocardial ischemia and angina pectoris.
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PMID:Effect of bepridil in patients with chronic stable angina: results of a multicenter trial. 388 May 21

Calcium channel blockers are assuming increasingly important roles in the practice of emergency medicine. Two cases and a review of the literature relating to treatment of hypertensive emergencies with nifedipine are presented. Nifedipine has a rapid onset of action (buccal, 10-15 minutes; oral, 30-45 minutes) and peak effect (buccal, 30 minutes, oral, 60 minutes). The duration of effects is four to six hours regardless of the route of administration, with a mean arterial pressure reduction of 21.6% (248/134 mm Hg to 165/87 mm Hg). In patients with severe hypertension and left ventricular failure, a consistent reduction in systemic vascular resistance (2,088 dynes/sec/cm-5 to 1242 dynes/sec/cm-5) and cardiac index (2.76 l/min/m2 to 3.77 l/min/m2) has been reported. The patients in this study had severe hypertension (systolic blood pressure greater than 180 mm Hg, diastolic blood pressure greater than 120 mm Hg) and end organ involvement (including heart failure, left ventricular strain, headache, confusion, dizziness, and shortness of breath). Nifedipine (10 mg) was administered buccally with prompt reduction of blood pressure and resolution of the patients' symptoms. Nifedipine appears to be a safe, effective agent for the management of hypertensive emergencies. Its pharmacokinetic profile and routes of administration make it particularly valuable in the practice of emergency medicine.
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PMID:Nifedipine in the management of hypertensive emergencies: report of two cases and review of the literature. 406 18

Fifty-one patients with essential hypertension, 22 males and 29 females with a mean age of 51 (range, 28 to 65 years), were studied for more than 12 months in a controlled clinical trial with nitrendipine, a new calcium antagonist agent. No differences in age, severity of hypertension, and other risk factors between the two sexes were detected. Forty-four of 51 patients completed the study, and 38 (86.4%) achieved a normalization of blood pressure. Mean systolic blood pressure decreased from 196.0 +/- 12.9 mm Hg (means +/- SD) during placebo to 171.2 +/- 9.5 mm Hg (12.6%, p less than 0.001) after 12 months. Mean diastolic blood pressure at the same time decreased from 109.0 +/- 5.2 mm Hg to 88.5 +/- 3.6 mm Hg (18.8%, p less than 0.001). Heart rate also decreased slightly but significantly (p less than 0.01) after the fifth week. A significant change in weight was not observed throughout the trial. Plasma potassium remained unchanged during the year, and plasma sodium after a transient increase (p less than 0.001) in the fifth week returned very close to basal levels in the sixth month. Side-effects were observed in 17 patients, 5 of whom had to leave the trial, but in the rest they were usually mild and transient. These were mainly frontal and occipital headache, facial flushing, ankle and pretibial oedema, and dizziness. No relationship was detected between side-effects and body weight or plasma sodium disturbances. Preliminary data on a separate group of 27 elderly patients (66-83 years) showed a better and faster effect of nitrendipine given in low doses.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinical experience with long-term nitrendipine treatment in essential hypertension. 608 73

The safety, tolerability and efficacy of PN 200-110, a new calcium antagonist with minimal negative inotropic effects, were studied in twelve patients with stable angina pectoris and coronary artery disease. The study design was single-blind and placebo-controlled and increasing doses of the drug were used on consecutive days to investigate a dose response relationship. Eleven patients completed the trial. Response to the drug was evaluated using symptom limited cycle ergometric exercise. PN 200-110 in all three tested doses of 2.5 mg, 5.0 mg and 10.0 mg significantly increased the resting heart rate (p less than 0.02) and the exercise time to the onset of angina pectoris (p less than 0.02). Doses above 2.5 mg did not appear to improve the exercise parameters evaluated. Four patients had side effects probably due to PN 200-110 but these were mild and included dizziness, headache and flushing. There were no abnormal results from haematological and biochemical screening or from urine testing. We conclude that PN 220-110 can be given safely to patients with coronary artery disease without producing deleterious effects on blood pressure either at rest or during exercise.
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PMID:Safety, tolerability and efficacy of PN 200-110, a new calcium antagonist in patients with angina and coronary heart disease. 624 Apr 5

Experience with flunarizine, a selective calcium-entry blocker, in the treatment of dizziness is reviewed. Clinical efficacy was predicted in pharmacological studies both in rabbits and humans: torsion swing or caloric induced nystagmus were significantly suppressed by flunarizine. Open therapeutic findings, using clinical and electronystagmographic or audiographic assessments as well, showed that flunarizine is of benefit to patients with vertigo of labyrinthine as well as of cerebrovascular origin. These results were confirmed in double-blind controlled trials. Flunarizine, either started with a loading dose gradually decreased thereafter, or given at a fixed 10 mg. dose schedule was proven to produce rapid improvement of dizziness and unsteadiness and to be tolerated very well.
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PMID:Flunarizine in the treatment of vertigo. 635 May 13

The pharmacokinetics, clinical efficacy, and adverse effects of three calcium-channel blocking agents--verapamil, nifedipine, and diltiazem--are reviewed. Verapamil, nifedipine, and diltiazem are absorbed well after oral dosing, but absolute bioavailability of each is reduced substantially by a first-pass effect. Each drug is metabolized extensively (verapamil and diltiazem to moderately active metabolites) by the liver. A substantial percentage of each drug is bound to plasma proteins, but the binding is of clinical importance only for nifedipine (92--98% protein bound). Intravenous verapamil has become the agent of first choice for treatment of acute paroxysmal supraventricular tachycardia (PSVT); use of chronic oral verapamil therapy for prophylaxis remains controversial. Verapamil and diltiazem have been evaluated with mixed results for atrial flutter and fibrillation. For treatment of myocardial ischemia, calcium-channel blockers may be of some value (possibly in combination with nitrates of B blockers). All three agents have been studied in patients with exertional angina with good results. Calcium-channel blockers appear to be equal with nitrates for treatment of variant angina. Patients with hypertropic cardiomyopathy have been treated with verapamil and nifedipine with promising results. Nifedipine has been effective for treatment of essential hypertension. Adverse effects of calcium-channel blockers have been relatively minor or infrequent. Diltiazem overall has the best side-effect profile, with adverse effects causing discontinuation of therapy in about 2--10% of patients; verapamil in intermediate (8--10%) and nifedipine the worst (17%) in this respect. The most common side effects generally are fatigue, headache, dizziness, skin rash, and peripheral edema. While they generally should be reserved for patients in whom more conventional therapy has failed (except those with PSVT), calcium-channel blockers appear to have a valid role as reserve agents for exertional and variant angina, cardiomyopathy, and hypertension.
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PMID:Update on calcium-channel blocking agents. 635 66


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