Central effects of the calcium antagonist, nifedipine

Solubilization and co-solubilization of carbamazepine and nifedipine in mixed micellar systems: insights from surface tension, electronic absorption, fluorescence and HPLC measurements

We present single and simultaneous solubilization of carabamezipine and nifedipine in mixed micelles.

Role of cinnarizine and nifedipine on anticonvulsant effect of sodium valproate and carbamazepine in maximal electroshock and pentylenetetrazole model of seizures in mice

OBJECTIVE

To study the effect of calcium channel blockers (CCBs) cinnarizine and nifedipine on maximal electroshock (MES)-induced and pentylenetetrazole (PTZ)-induced convulsions and also their effect in combination with conventional antiepileptic drugs (CAED).

MATERIALS AND METHODS

For this study, Swiss albino mice were used. Effects of cinnarizine (30 mg/kg), nifedipine (5 mg/kg), sodium valproate (300 mg/kg) and carbamazepine (8 mg/kg) alone and in combination were studied in MES and PTZ seizure models. Abolition of hind limb tonic extension was an index of anticonvulsant activity in MES, while for PTZ seizures, failure to observe even a single episode of tonic spasm for 5 s duration for 1 h was the index. With this, percentage protection was calculated and statistical analysis was carried out using Fisher's exact test (Ovvind Langsrud software, German version).

RESULTS

In MES seizures, augmented effects were obtained when cinnarizine was combined with sodium valproate, i.e. 100%. In PTZ-induced seizures, augmented effects were obtained when nifedipine was combined with sodium valproate, i.e. 100%. Thus, cinnarizine added to sodium valproate therapy produces significant protection against MES seizures while nifedipine added to sodium valproate therapy produces significant protection against PTZ seizures.

CONCLUSION

The results provide a lead for potential benefit of adding CCBs to sodium valproate in the treatment of epilepsy, which needs to be explored further.

Effects of nicardipine and clonidine on cognitive functions and electroencephalography in hypertensive patients

The aim of this study was to investigate the cognitive and electroencephalography (EEG) short-term effects of a calcium antagonist, nicardipine, compared to placebo and clonidine (which, having known sedative effects, acted as a negative control) for 15 days in elderly hypertensive patients with memory complaints. Nicardipine and clonidine were compared with placebo in a double-blind, randomized, three-way cross-over controlled study after a 2-week placebo run-in period. This was a phase II clinical study carried out on out-patients in a single research centre. Fifteen elderly (63 +/- 10 years) hypertensive patients, without dementia but with memory complaints, were included. Psychomotor performance and cognition were assessed using both an extensive battery of validated psychometric tests (which evaluated attention and vigilance, body sway and memory) and an EEG profile. Cardiovascular parameters measured were blood pressure and heart rate. No detrimental effects of nicardipine were found on attention, vigilance, body sway or memory. Nicardipine produced a significant increase in alpha EEG energies, which may indicate possible alerting effects. In contrast, clonidine induced well-known deleterious sedative effects in psychometric tests and in EEG analysis (decrease in alpha and increase in delta and theta waves). The two drugs produced equivalent decreases in blood pressure at steady state. In conclusion, clonidine induced well-known sedative effects, while nicardipine did not impair central nervous system activity and may have had some short-term alerting effects in elderly hypertensive patients with memory complaints. This study supports the hypothesis of a dissociation between blood pressure and direct drug effects on the central nervous system.

Effect of combined atenolol and nifedipine administration on psychomotor performance in normal subjects

The aim of the present study was to evaluate the central effects of single doses of the beta-adrenoceptor antagonist atenolol and the calcium antagonist nifedipine retard, alone and in combination, in normal subjects. Twelve normal males received single oral doses of atenolol 100 mg, nifedipine retard 20 mg, atenolol 100 mg and nifedipine retard 20 mg in combination, diazepam 5 mg (active control), and each of two matching placebos in a double-blind, randomised fashion. Psychomotor performance was assessed using digit symbol substitution, letter cancellation (LCT), continuous attention, choice reaction time, finger tapping, immediate recall and short-term memory. Two flash fusion and critical flicker fusion thresholds were measured and subjective assessments made using visual analogue scales (VAS). Diazepam 5 mg significantly worsened LCT scores at 4h, significantly impaired alertness at 2 h and 4 h, and tended to increase reaction time and impair continuous attention and physiological measurements. Atenolol 100 mg alone significantly reduced alertness at 2 h and 4 h, and also tended to impair physiological measurements. Nifedipine retard 20 mg produced no significant psychomotor effects. Combined atenolol and nifedipine retard administration produced a small but significant improvement in continuous attention and a reduction in body sway, with no adverse effects being evident on performance or subjective awareness. The results suggest that no significant adverse effects on psychomotor performance are produced by single doses of atenolol 100 mg and nifedipine retard 20 mg when given together in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Vigilance impairment after a single dose of benzodiazepines

While outpatients or other users of therapeutic drugs have to be informed about the risk of impaired functioning during driving or work, the prescribing physician needs to be familiar with the side effects of alternative drugs in order to select the most suitable treatment. With this aim, several types of benzodiazepine anxiolytics in low anxiolytic doses (diazepam 5 mg or 10 mg, nitrazepam 5 mg, oxazepam 10 mg, medazepam 10 mg, and alprazolam 0.2 or 0.5 mg-per 2m2 body surface) were tested under laboratory conditions for their effects on vigilance performance. In a double-blind design, 145 healthy volunteers performed a 60 min vigilance test (composed of discriminatory reactions to acoustic stimuli and a secondary visual tracking task) and four short psychomotor tests (lasting 1-7 min each) before and after a single dose of drug or placebo. Subjects described their perception of the drug effect with the help of a mood check list, and fatigue, sleepiness, and effort scales. Only diazepam 5 mg and 10 mg, alprazolam 0.5 mg, and nitrazepam 5 mg caused significant deterioration in vigilance performance along with perceived sleepiness and the need for a greater effort to overcome it. The onset of diazepam effect was quicker, whereas alprazolam effect lasted longer. No effect was noted in the short psychomotor tests except for the Bourdon Cancellation Test, where the first phase of diazepam effect was registered.

Central effects of the diuretic, bendrofluazide

1. Central effects of the diuretic, bendrofluazide (2.5, 5 and 10 mg) were studied in 12 healthy volunteers. Two placebos and an active control drug, oxazepam (15 mg), were included. Single doses were administered double-blind at 10.00 h. The effects of drugs on performance and subjective feelings were assessed before and from 1.5-2.5 and 3.5-4.5 h after ingestion, and recording of the electrical activity of the brain (EEG) and body sway carried out. 2. Performance was assessed using digit symbol substitution, continuous attention, letter cancellation, choice reaction time, finger tapping, immediate and short-term memory, together with critical flicker fusion and two flash fusion. Subjects assessed their mood and well-being on a series of 12 visual analogue scales. The EEG was recorded with eyes open while the subjects carried out a mental arithmetic task, and with eyes closed, when they were required to relax. Body sway was recorded with eyes open and with eyes closed. 3. Bendrofluazide (10 mg) increased the number of errors at letter cancellation and reduced the rate of finger tapping (P < 0.05), while oxazepam increased the number of errors and reduced accuracy at continuous attention (P < 0.01), and increased the number of involuntary rest pauses during tapping (P < 0.05). 4. There were no effects of drugs on subjective assessment of mood. 5. No changes in the electrical activity of the brain were observed with bendrofluazide. In recordings with eyes open, oxazepam reduced delta (0.5-3 Hz), theta (3.5-7 Hz) and alpha 2 (10.5-13 Hz) while increasing beta 1 (13.5-21 Hz) activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Psychomotor performance and antihypertensive treatment

1. The aim of treatment of hypertension is prevention of cardiovascular complications without adverse drug reactions. Psychomotor performance can be measured objectively yet there remains uncertainty concerning the psychomotor effects of antihypertensive drugs during chronic treatment. This uncertainty is partly due to the confounding adverse effects of cerebrovascular disease and hypertension itself. There are as yet insufficient good quality data on psychomotor effects with which to differentiate between the commonly used agents. However, in general, the beneficial effect of lowering blood pressure tends to more than offset any adverse effects of the agent used.

Central effects of combined bendrofluazide and atenolol administration. A single dose study in normal subjects

Twelve normal male subjects received single oral doses of atenolol 100 mg (AT), bendrofluazide 5 mg (BFZ), combined atenolol 100 mg and bendrofluazide 5 mg (AT/BFZ), diazepam 5 mg (Dz), or one of two matching placebos, on each of 6 study days. Tests of psychomotor performance [digit symbol substitution (DSST), letter cancellation (LCT), continuous attention, choice reaction time (CRT), finger tapping, short-term memory, body sway], physiological measurements [critical flicker fusion (CFF), two-flash fusion (2FF)] and subjective assessments using visual analogue scales (VAS), were performed at 2 and 4 hours post-ingestion. Dz (active control) significantly worsened VAS scores at 2 h (+0.68) and reduced DSST scores at both 2 h (-15.0) and 4 h (-11.0). AT and BFZ given alone, each produced significant worsening of VAS at 2 h [AT +1.0; BFZ +1.38], but had no significant effects on performance. In combination however, AT/BFZ at 4 h produced significant impairment of DSST scores (-10.4), reduced finger tapping (-16.5) and increased involuntary rest pauses (+16.5). Despite these effects, no change in VAS scores occurred. In summary, we have demonstrated significant impairment of psychomotor performance in normal subjects with the AT/BFZ combination, which was not evident with the single agents and which occurred in the absence of a change in subjective awareness. These central effects may have important clinical implications for patients taking combined antihypertensive medication.

The effects of anti-hypertensive medication on learning and memory

1. The aim of the study was to investigate whether there were differential effects of three different anti-hypertensive medications (cilazapril, atenolol, nifedipine) on cognitive function. 2. A sub-group of patients participating in a large clinical trial of these three drugs, randomly allocated between the three drug conditions, received cognitive assessment at two points before the commencement of treatment and then after 12 and 24 weeks of treatment. Seventy-six patients began treatment, and 55 completed the full course. 3. Tests of learning and memory were designed specially for the study, with a different but comparable version administered on each assessment occasion, in a fixed order. 4. No significant differences between drug groups were found in any index of learning or memory, at any testing occasion. The results were the same whether or not treatment non-completers were included in the analysis.

Quality of life in the treatment of hypertension. The effect of calcium antagonists

The effects of calcium antagonists on psychological well-being, cognitive function, activity and physical symptoms in hypertensive patients are reviewed. Effects on these aspects of quality of life appear to differ according to whether a dihydropyridine calcium antagonist such as nifedipine is employed or verapamil, which is a phenylalkylamine derivative. Nifedipine has been associated with a self-assessment of impaired cognitive function in 2 clinical trials. Nifedipine was also associated with more symptomatic complaints than both atenolol and verapamil in different studies. The problems with nifedipine centred on oedema, flushing and palpitations. Verapamil was associated with constipation. Compared with other classes of antihypertensive drugs, the position of calcium antagonists with respect to the maintenance of patients' quality of life is presently unclear. Verapamil has been associated with improved quality of life compared with propranolol (a beta-blocker) and nifedipine. Verapamil appears to have similar effects on quality of life as atenolol and the angiotensin converting enzyme (ACE) inhibitor, captopril. The position of nifedipine remains unclear.