Behavioral effects of chronic, orally administered diuretic and verapamil in baboons

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)

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.

General activity in baboons measured with a computerized, lightweight piezoelectric motion sensor: effects of drugs

A small, 1-oz activity-monitoring device is described for measuring motor activity continuously for periods of up to 42 days. The monitor employs a piezoelectric sensor that detects extremely small accelerations induced by movements. The monitor can be placed on collars or harnesses (e.g., for rabbits, cats, dogs, nonhuman primates, etc.). The use of the monitor is described within numerous laboratories studying the behavioral pharmacology of drugs in individually caged laboratory baboons. Patterns of daily activity were reliably recorded over periods of several months, and reflected the normal activity patterns of animals. The activity monitor recorded reliable, drug-induced changes in general activity that paralleled the known effects of the same drugs on learned behaviors. Low doses of the stimulants cocaine and d-amphetamine both increased general activity. Marked reductions in general activity were observed following both the administration of delta-9-tetrahydrocannabinol and an antihypertensive drug combination of diuretic and verapamil.

Behavioral performance effects of verapamil in normotensive and renovascular hypertensive baboons

Behavioral performances of normotensive and hypertensive adult male baboons were tested before, during, and following chronic oral dosing with verapamil. Performances during a five-color simultaneous match-to-sample task were measured for two doses (2.0, and 3.2 mg/kg/day) and vehicle. Each dose was administered for 21 consecutive days preceded and followed by 14-day baseline and recovery periods, respectively. Choice reaction times increased by 9% during the lower dose of verapamil, compared to vehicle; choice reaction times were unchanged at the higher dose. At baseline and during vehicle administration, the yellow and white stimuli were the most difficult to discriminate correctly; discrimination of these colors was slightly impaired by the lower, but not the higher dose of verapamil. Verapamil's behavioral effects were not modulated by blood pressure changes since both baboon groups showed equivalent changes in behavioral performance, but only renovascular hypertensive baboons showed blood pressure decreases. Verapamil appears to be an effective hypotensive and does not produce profound psychomotor impairment at clinically used doses during the first weeks of treatment.

Chronic hydrochlorothiazide and verapamil effects on motor activity in hypertensive baboons

Spontaneous motor activity was measured in six baboons during chronic oral dosing with a diuretic (hydrochlorothiazide/triamterene), a calcium channel blocker (verapamil), and a combination of the two drugs. Piezoelectric monitors sensitive to movement were attached to leather collars and were worn continuously by the baboons throughout the protocol. Baboons were made hypertensive during a preexperimental period by either 1) chronic administration of deoxycorticosterone acetate (DOCA)-salt or 2) surgical renal artery stenosis. Total inactive periods/day increased over baseline levels during diuretic alone and increased further during diuretic + verapamil combined. The total number of inactive periods/day returned toward baseline levels in the subsequent conditions of verapamil alone and baseline recovery. Activity levels decreased during combination dosing mainly during morning hours (0700-1100 h). Overall changes in activity occurred in the second week of dosing; this time period was found earlier to maximally decrease blood pressure and to impair behavioral performances.