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Biomedical subjects

L E Mather

Publications and source records attributed to L E Mather.

At least 163 records · Page 9Linked to original sources
PubMed1979

A pharmacokinetic approach to postoperative pain: continuous infusion of pethidine.

In an attempt to improve postoperative pain management an intravenous infusion of pethidine was designed to provide stable therapeutic blood concentrations. Ten female patients undergoing elective abdominal hysterectomy were studied. After commencement of the infusion, blood pethidine concentrations increased rapidly and exceeded 0.46 microgram/ml after four hours. The mean steady-state concentration of 0.67 microgram/ml was reached by twenty-four hours. This infusion regimen resulted in the abolition of severe pain after three hours and analgesia continued for the duration of the two day study. Significant blood concentrations of the metabolite norpethidine were found although clinically no toxic effects were observed. Side effects of pethidine were infrequent. Controlled continuous intravenous infusion of pethidine produced stable blood concentrations and provided excellent pain control.

Adult↗
PubMed1979

Cardiovascular and subjective central nervous system effects of long-acting local anaesthetics in man.

Intravenous infusions of etiodocaine 50, 75 and 100 mg and bupivacaine 75 mg were carried out over ten minutes in healthy young adult males. Cardiovascular sequelae were generally trivial at all doses. A collection of subjective central nervous system symptoms were described which may be regarded as early warning of impending local anaesthetic toxicity. Plasma concentrations of etidocaine were proportional to dose and ranged from 2 micrograms/ml to 5 micrograms/ml at the termination of the infusion. Plasma concentrations of bupivacaine were similar to those from the same dose of etidocaine but declined more slowly on cessation of infusion.

Acetanilides↗
PubMed1978

Simultaneous quantitation of morphine and paraben preservatives in morphine injectables.

A high-performance liquid chromatographic method for the simultaneous determination of morphine sulfate, methylparaben, and propylparaben in morphine sulfate injection was developed. A reversed-phase system, based on an octadecylsilane stationary phase, was used with a binary solvent mobile phase consisting of methanol--phosphate buffer (pH 4.0) containing methanol (5%) delivered at a constant rate (0.6:0.4 ml/min) using a two-pump system. The detector response at 254 nm was linear with the amount injected over a wide range, allowing rapid and reproducible quantitation of each component.

Chromatography, High Pressure Liquid↗
PubMed1977

Bupivacaine (Marcaine): an evaluation of its tissue and systemic toxicity in humans.

In countries other than the U.S.A., dosages of bupivacaine have been limited to 100 mg without epinephrine and 150 mg with epinephrine. A review of 7,688 regional block procedures employing bupivacaine in concentrations of 0.25, 0.5, and 0.75%, and in dosages as high as 600 mg, indicated that such stringent restrictions: (1) are unwarranted, (2) make comparisons with other local anesthetic agents difficult, and (3) are in need of revision.

Adolescent↗
PubMed1976

Systemic availability of orally administered meperidine.

A comparison of the areas under the plasma concentration-time curves after intravenous and oral administration of meperidine in 4 normal subjects indicated that 48% to 56% of the oral dose avoided "first-pass" metabolism and was systemically available. Similar estimates were obtained by applying the Loo-Riegelman method for calculating drug absorption viz, 47% to 60%. Oral availability predicted from a knowledge of drug clearance (blood) after intravenouration-time curves after oral administration exhibited irregularities and double peaks possibly indicative of the action of meperidine on the gut or a recycling process.

Administration, Oral↗
PubMed1976

The effects of adding adrenaline to etidocaine and lignocaine in extradural anaesthesia II: Pharmacokinetics.

The addition of adrenaline to solutions of etidocaine or lignocaine for extradural administration resulted in significantly lower plasma koncentrations in both the arterial blood (14% decrease for etidocaine and 43% decrease for lignocaine) and venous blood (35% and 60% decreases for etidocaine and lignocaine respectively). The nett absorption over the first 4 h after administration, measured from the area under the plasma concentration-time curve, was decreased by the addition of adrenaline (18% and 30% decreases for etidocaine and lignocaine respectively). Both drugs were absorbed in a biexponential manner, having similar fast absorption rates but with etidocaine having a longer absorption half-life in the slow absorption phase. It is concluded that the addition of adrenaline reduces the fraction of the dose being absorbed during the first (fast) phase rather than influencing the absorption rate constants.

Absorption↗
PubMed1976

Effects of extradural block: comparison of the properties, circulatory effects and pharmacokinetics of etidocaine and bupivacaine.

Five healthy, unmedicated male volunteers, aged 19-25 yr, participated in a double-blind, crossover study. Each subject received, on separate occasions and via a catheter placed at L2, 1.5% etiodocaine HCl20 ml with adrenaline 5 mug/ml, or 0.75% bupivacaine HCl 20 ml with adrenaline 5 mug/ml for extradural analgesia. In addition, in order to calculate the absorption rate of the local anaesthetic agent, each subject received on two further occasions etidocaine HCl 75 mg and bupivacaine HCl 75 mg respectively by i.v. infusion, over a period of 10 min. Spread of sensory analgesia to four segments above and below the site of injection was faster with etidocaine (13 +/- 3 min) (mean +/- SD) than with bupivacaine (22 +/- 8 min). Two-segment regression occurred later for bupivacaine (260 +/- 57 min) than for etidocaine (180 +/- 96 min). Caudal spread of analgesia was more extensive with etidocaine than with bupivacaine. The onset of motor blockade tended to be faster with etidocaine (5.8 +/- 3.0 min), than with bupivacaine (10.0 +/- 3.5 min); regression of motor blockade by one unit was longer with etidocaine (306 +/- 103 min) than bupivacaine (238 +/- 75 min). Sudomotor block occurred earlier with etidocaine (4.0 +/- 2.1 min) than bupivacaine (13.7 +/- 4.8 min). Significant changes in cardiac stroke work and stroke volume occurred. For etidocaine these measurements remained below control values for 120-210 min after injection. The mean maximum arterial plasma concentration of etidocaine was 1.52 +/- 0.64 mug/ml, at 14 +/- 2 min and of bupivacaine was 1.35 +/- 0.63 mug/ml, achieved at 20 +/- 4 min. The systemic absorption of both drugs occurred in a biphasic pattern with a fast and slow half-life of 0.3 and approximately 8 h respectively.

Acetanilides↗
PubMed1976

The effects of adding adrenaline to etidocaine and lignocaine in extradural anaesthesia I: block characteristics and cardiovascular effects.

The addition of adrenaline 5 mug/ml, 1 : 200 000 to 1% etidocaine hydrochloride administered extradurally (L2-3) shortened significantly the onset time for sensory blockade, particularly with respect to the spread of the analgesia from the injection site, and shortened the already rapid onset of motor block. Etidocaine hydrochloride 1% plain caused a slower onset of block, laster longer and produced more profound analgesia over the caudal dermatomes than did 2% lignocaine hydrochloride. The motor block from plain etidocaine was more profound in its extent and lasted longer than that caused by lignocaine. With regard to cardiovascular variables, there were no significant differences between subjects receiving the plain etidocaine and the plain lignocaine. However, subjects receiving etidocaine with adrenaline exhibited increased cardiac stimulation and a decrease in total peripheral resistance over the first 150 min.

Acetanilides↗
PubMed1976

Arterial and venous plasma levels of bupivacaine following epidural and intercostal nerve blocks.

Arterial and peripheral venous plasma levels of bupivacaine were determined in 30 patients following epidural anesthesia using 150 and 225 mg, as well as following intercostal nerve block with 400 mg. Arterial levels were consistently higher than levels in simultaneously sampled venous blood, and the highest levels occurred with bilateral intercostal nerve block. No evidence of systemic toxicity was observed. The results suggest that bupivacaine may have a wider margin of safety in man than is now stated.

Adult↗