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Biomedical subjects

B E Rodda

Publications and source records attributed to B E Rodda.

At least 19 recordsLinked to original sources
PubMed1977

GLC determination of acetohexamide and hydroxyhexamide in biological fluids.

A sensitive and specific GLC assay was developed for acetohexamide and hydroxyhexamide, its major metabolite, in plasma and urine. The assay uses tolbutamide as a mass internal standard. Compounds are extracted from acidified plasma or urine with toluene, converted to methylated derivatives with dimethyl sulfate, and measured by GLC using a flame-ionization detector. With GLC-mass spectrometry, the compounds measured are the N-methylsulfonamides resulting from GLC pyrolysis. Plasma and urine data are presented from a bioavailability study to demonstrate the utility of this method.

Acetohexamide↗
PubMed1977

Subjective responses and excretion patterns of dextroamphetamine after the administration of therapeutic doses.

Twelve male medical and graduate students received dextroamphetamine sulfate in doses of 0, 5, 10, and 15 mg/70 kg body weight. The study was conducted in a double-blind manner, and treatments were assigned according to randomized, complete block design. The drug was given orally and subjects were instructed not to eat 3 1/2 h prior to administration. After administration, total urine output was collected for 12 h; no attempt was made to control urinary pH to more realistically approach the general clinical usage of amphetamines. The urine was pooled into two 6-h segments and analyzed for amphetamine concentration. Subjective impressions of the treatments were also evaluated by means of the Cornell Medical Index Questionnaire. Results showed that approximately 30% of the total dose was excreted unchanged within 12 h after administration. The amount excreted agreed very closely with the doses given and paralleled the scores for subjective impressions by the subjects. None of the subjects felt that their driving would be impaired for any of the doses administered. This study indicates that under ordinary conditions (in which pH is not artificially controlled), therapeutic doses of dextroamphetamine can be detected in urine for up to 12 h after oral administration.

Administration, Oral↗
PubMed1976

Influence of cannabidiol on delta-9-tetrahydrocannabinol effects.

Experiments investigating the possible interaction of tetrahydrocannabinol (THC) and cannabidiol (CBD), two major components of marihuana, were conducted under controlled laboratory conditions in a double-blind manner. In one study, 15 male volunteers were given placebo or 25 mug/kg of THC together with either placebo or 150 mug/kg of CBD by inhalation of the smoke of a single cigarette. All four treatments were assigned to each subject according to a series of Latin-square designs. CBD significantly attenuated the subjective euphoria of THC. Psychomotor impairment due to THC was not significantly altered by the simultaneous administration of CBD, but a trend indicating a decrease in THC-like effects was observed after the combination. When administered alone CBD was inactive for all the parameters measured. In a second study, 8 male subjects were given CBD (0 or 150 mug/kg) by smoke inhalation 30 min before THC (0 or 25 mug/kg) in a second cigarette. In contrast to the simultaneous administration of both drugs, CBD pretreatment did not alter the effects of THC on the parameters observed.

Adult↗
PubMed1976

Effects of dextroamphetamine on psychomotor skills.

Twelve healthy male volunteers were given 0, 5, 10, 15 mg/70 kg dextroamphetamine orally in a randomized double-blind fashion. Blood pressure increased linearly with dose while heart rate was unchanged. Although selected individual tests of stance stability and motor function improved in a dose-related fashion, a generalized improvement in performance was not found. Delayed Auditory Feedback (DAF) failed to show improvement in mental performance after dextroamphetamine.

Acoustic Stimulation↗
PubMed1976

Effects of marihuana-dextroamphetamine combination.

Under a double blind, randomized, complete block design, subjects were given either placebo and 10 mg/70 kg dextroamphetamine sulfate (A) orally followed 1 1/2 hr later by a marihuana cigarette (M) prepared to deliver 50 mug/kg delta-9-tetrahydrocannabinol (THC). Statistical analyses suggested that heart rate and blood pressure increased in an additive manner when both drugs were given. Electrocardiogram changes, when present, were nonspecific in character and appeared to be associated with marihuana. In a second study, psychomotor performance was evaluated by a similar design using doses of 10 mg/70 kg of A and M prepared to deliver 25 mug/kg THC. Impairment was related to smoking of M, and no difference could be distinguished between M alone and M-A combination. Subjective evaluation, as measured by the modified Cornell Medical Index (CMI) demonstrated only additive effects for the combination.

Adult↗
PubMed1976

Influence of cannabidiol on secobarbital effects and plasma kinetics.

To investigate the possible metabolic interaction between cannabidiol (CBD) and secobarbital, 6 male volunteers received 150 mg/70 kg sodium secobarbital orally immediately after smoking a marihuana cigarette prepared to deliver 0, 150, or 500 mug/kg CBD. The study was performed in a double-blind manner with each of the three treatments being assigned to every subject. Clinical effects and plasma secobarbital concentrations were recorded at periodic intervals. CBD did not alter the summary parameters which describe the secobarbital plasma concentration time curve. Secobarbital half-life, peak concentration, time of peak concentration, and area under the curve were unchanged by the coadministration of CBD. Clinical effects of secobarbital were also unaltered by CBD pretreatment. Thus at the doses administered, CBD does not appear to inhibit secobarbital metabolism in man.

Adult↗
PubMed1976

Optimal visualization of esophageal varices.

Twelve patients with known esophageal varices and willingness to cooperate were included in the study. Medications administered were placebo, 2 mg of glucagon, and 30 mg of propantheline bromide. All medications were given double-blind and crossover. On the basis of this study the authors believe that for optimal visualization of esophageal varices the following is the procedure of choice: (1) the patient should remain horizontal (this is best done in the left lateral position for comfort and ease of expectoration) for ten minutes after swallowing high density barium; (2) the patient should "clear his throat" frequently and expectorate all saliva (barium sticks to the pharynx and makes the patient want to swallow and "clearing his throat" by forced expiration helps the patient to expectorate this coating and prevents swallowing); (3) filming should be done in expiration in the supine (left posterior oblique to table top) position; and (4) in equivocal cases the examination can be repeated with an anticholinergic drug if the patient has no contraindications to its use. The patient should empty his bladder just before administration of the drug. The intelligent use of these factors should result in a saving of both fluoroscopic time and film, and give the radiologist a safe optimal diagnostic yield.

Adult↗
PubMed1976

Analgesia, plasma levels, and dosage of propoxyphene.

It can be shown that both the mean plasma levels observed and the mean analgesic scores (effectiveness) are related to the dose of an orally effective analgesic agent, although wide individual variations exist. Based on the pharmacokinetic characteristics of propoxyphene, it can be predicted and confirmed that equilibrium (or steady state) plasma levels will be achieved after about six doses when administered on a q. 6h. schedule. Similar predictions indicate that an initial loading dose of 2 to 2 1/2 times the maintenance dose will produce more promptly plasma levels within or close to the equilibrium levels.

Analgesia↗
PubMed1975

Effects of marihuana combined with secobarbital.

Twelve male volunteers smoked a marihuana cigarette prepared to deliver 0 or 25 mug/kg tetrahydrocannabinol (THC) 50 min after ingesting a capsule containing either placebo or 150 mg/70 kg sodium secobarbital. Drugs were administered in a double-blind manner, and all treatments were assigned to each subject in a randomized complete block design. Objective and subjective tests designed to measure mental and motor performance indicated that marihuana impaired stability, hand-eye coordination, and mental performance. Secobarbital affected motor performance, manual coordination, and mental performance. In combination, marihuana and secobarbital had an additive effect on subjective responses and impairment in certain psychomotor performance tests.

Adult↗
PubMed1975

Problems and solutions to single-dose testing of analgesics: comparison of propoxyphene, codeine, and fenoprofen.

Discrepancies exist between reports arising from single-dose and multiple-dose studies intended to compare the efficacy of oral analgesics. D Differences in the pharmacokinetic characteristics of these drugs account for much of the discord. Codeine and fenoprofen rapidly achieve their ultimate plasma equilibrium levels (on a q. 6h. schedule), whereas, propoxyphene requires a longer period, doubtless due to its longer half-life and proportionately smaller maintenance dose. If the drugs are not to be compared during the steady state, then administration of appropriate loading doses permits satisfactory single dose comparisons at steady-state concentrations.

Analgesics↗