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R Cronnelly

Publications and source records attributed to R Cronnelly.

27 records · Page 2Linked to original sources
PubMed1980

Reversed-phase, ion-pair liquid chromatography of quaternary ammonium compounds: determination of pyridostigmine, neostigmine and edrophionium in biological fluids.

A reversed-phase, ion-pair liquid chromatographic method for the quantitative determination of quaternary acetylcholinesterase inhibitors is described. The method uses an ion-pair extraction to isolate the drugs from biological material prior to liquid chromatographic separation and online UV detection at 214 nm. Quantiation down to 5 ng/ml and within-day precison with coefficient of variation (C.V.) of 1.5% (n = 10, x = 100 ng/ml) for neostigmine, C.V., 1.7% (n = 10, x = 80 ng/ml) for pyridostigmine and C.V., 1.5% (n = 10, x = 100 ng/ml) for edrophonium have been achieved. The assay was designed for pharmacokinetic studies of these drugs in anesthetized patients.

Chromatography, Liquid↗
PubMed1980

Pyridostigmine kinetics with and without renal function.

Pyridostigmine kinetics were examined under conditions of clinical use as an antagonist of nondepolarizing neuromuscular blockade in anesthetized patients with and without renal function. Pyridostigmine serum levels were assayed by gas-liquid chromatography, and data were fitted to a 2-compartment kinetic model. Pyridostigmine kinetics following renal transplantation (n = 5) were not different from those in patients with normal renal function. Renal function (n = 5) elimination half-life increased from 112 +/- 12 min (mean +/- SD) to 379 +/- 162 min, and serum clearance decreased from 9 +/- 2 ml/kg/min to 2 +/- 0.6 ml/kg/min in anephric patients (n = 4). We conclude that renal function accounts for 75% of pyridostigmine clearance.

Adult↗
PubMed1975

Studies of the neuromuscular blocking effects of BW 403C65 in frog and cat muscle.

BW 403C65, an isoquinolinium bisquaternary compound, was investigated for its neuromuscular blocking properties. In vitro in from preparations, low concentrations induced an increase in miniature endplate potentials (m.e.p.p.) frequency without altering their amplitude. With increasing concentrations m.e.p.p. frequency returned to control value and amplitude started to decrease concomitantly with the decreased sensitivity of the endplate to iontophoretically applied acetylcholine and depression of the twitch tension. Acetylcholine released at the neuromuscular junction was also decreased. In vivo in the cat preparation the intra-arterial injection of low doses of the drug produced an increase in the strength of the muscle twitch, and the development of contracture, as well as the appearance of post-drug repetition at the ventral roots. Greater doses produced a progressive decline in post-tetanic potentiation with prolonged return to control.

Acetylcholine↗
PubMed1975

Actions of a new muscle relaxant (AH8165) on neuromuscular transmission.

The effects of a new muscle relaxant, AH8165, on miniature endplate potential (MEPP) amplitude and frequency, endplate sensitivity to acetylcholine, and muscle twitch tension were studied in vitro in the frog sartorius muscle. Nerve terminal effects were studied in vivo in the cat soleus muscle and its ventral root fibers. AH8165 stimulates the nerve terminal, as evidenced by increased MEPP frequency and the appearance of post-drug repetitive activity. In the same concentration range at which MEPP frequency is increased, MEPP amplitude, endplate sensitivity to acetylcholine, and twitch tension are decreased. This suggests that AH8165 produces muscle relaxation by blocking postsynaptic cholinergic receptors. (Key works: Neuromuscular relaxants, AH8165.).

Acetylcholine↗