An HPLC method for analysis of clonazepam in serum

A sensitive, accurate, and precise method for the analysis of clonazepam in serum was developed. The drug and internal standard from serum extracts were methylated to obviate carbamazepine interference and then resolved on a 5 micron C18 HPLC column. The mobile phase could also be used for many other basic drugs.

Effects of tri-n-butyl phosphate on the peripheral nervous system of the Sprague-Dawley rat

Tri-n-butyl phosphate, a widely used plasticizer and solvent, was orally administered to male and female Sprague-Dawley rats for 14 consecutive days (low dose: 0.28 mL/kg; high dose: 0.42 mL/kg). Effects of this industrial chemical were investigated on the peripheral nervous system of these animals. A significant (P less than 0.05) reduction in conduction velocity of caudal nerve was observed in high dose male rats. Electron microscopic examination of sciatic nerve showed morphological changes such as retraction of Schwann cell processes surrounding unmyelinated fibres in both sexes of high dose groups.

The effect on heart rate of neuromuscular blockade reversal by pyridostigmine

Pyridostigmine without atropine, pyridostigmine with atropine or neostigmine with atropine were used to antagonise neuro-muscular blockade induced by d-tubocurarine in forty otherwise healthy, female patients recovering from gynaecological surgery. Pulse rates fell significantly (P less than 0.01, control heart rate 72 +/- 18 beats/min (M +/- SD) to 55 +/- 13 beats/min) at ten minutes after pyridostigmine (10 mg/70 kg), necessitating administration of atropine (1.25 mg/70 kg) by fifteen minutes after pyridostigmine. After an initial rise in rate, pulse rates also fell significantly (P less than 0.01, control heart rate 70 +/- 12 beats/min to 44 +/- 11 beats/min) at fifteen minutes after injection of neostigmine (2.5 mg/70 kg) with atropine (1.25 mg/70 kg). By contrast when pyridostigmine and atropine were used together, pulse rates rose and then fell, but mean values never fell below control during a twenty-minute observation period. It was concluded that pyridostigmine should not be given alone, but requires the use of atropine to prevent bradycardia. This combination may, however, provide a more stable heart rate than that seen with neostigmine and atropine in usual doses, when these drugs are used to antagonise d-tubocurarine.

Cutaneous and venous complications of pentazocine abuse

A 55-year-old man with a two-year history of intramuscular pentazocine abuse had classical cutaneous findings as well as secondary venous thrombosis, which, to our knowledge, is previously undescribed. Histologic evaluation, including direct immunofluorescent microscopy, did not establish the mechanism of tissue destruction.

Plasma protein binding and placental transfer of bupivacaine

The maternal venous and umbilical venous plasma concentrations of bupivacaine were determined at delivery following epidural administration of the drug to 31 women in labor. In each case the umbilical venous plasma concentration of bupivacaine was lower than the maternal venous plasma concentration. There was no significant difference between the concentration of unbound bupivacaine in umbilical venous and maternal venous plasma at delivery. The difference in umbilical and maternal plasma concentrations of bupivacaine appears to be a consequence of greater bupivacaine binding to maternal than to fetal total plasma protein. The intersubject variation of the ratio of bupivacaine concentration in fetal plasma/bupivacaine concentration in maternal plasma was found to be related to individual variation in the extent of protein binding of bupivacaine in maternal and umbilical plasma and correlated positively with the variation of the ratio of total protein concentration in umbilical and maternal plasma.

The effects of r- and K-selection on components of variance for two quantitative traits

The genetic and environmental components of variance for two quantitative characters were measured in the descendants of Drosophila melanogaster populations which had been grown for several generations at densities of 100, 200, 300, and 400 eggs per vial. Populations subject to intermediate densities had a greater proportion of phenotypic variance available for selection than populations from either extreme. Selection on either character would be least effective under pure r-selection, a frequent attribute of selection programs.