Plasma concentrations of local anaesthetics after interscalene brachial plexus block.

Plasma concentrations of local anaesthetic agents have been measured after 40 interscalene brachial plexus blocks in 39 patients, using lignocaine, prilocaine, bupivacaine and etidocaine. Lignocaine produced greater concentrations than prilocaine, and bupivacaine greater concentrations than etidocaine. The addition of adrenaline resulted in much lower concentrations in the case of all four agents.

Determination of debrisoquine and its 4-hydroxy metabolite in biological fluids by gas chromatography with flame-ionization and nitrogen-selective detection.

Specific methods have been devised for the simultaneous determination of the guanidino-type antihypertensive agent debrisoquine and its 4-hydroxy metabolite in human urine, involving in situ derivatisation with acetylacetone, extraction of the resulting pyrimidines, and gas chromatography using a flame-ionisation detector or a nitrogen-specific detector. Using the latter, a similar procedure was also developed to measure debrisoquine in human plasma and whole blood following prior extraction at pH 13.5 with chloroform.

Observed and predicted accumulation of local anaesthetic agents during continuous extradural analgesia.

After lumbar extradural injections of ligocaine or etidocaine for surgical anaesthesia further accumulation in the plasma was minimal following top-up injections for pain relief after operation. The dose regimens were: 20 ml of 2% plain lignocaine HCl solution for surgical anaesthesia followed by 10 ml every 1 h until 4 h, and 20 ml of 1% plain etidocaine HCl solution for surgical anaesthesia followed by 10 ml every 2 h until 8 h. Plasma drug concentrations measured after initial doses were used to predict those following successive doses.

Why hypertensive patients vary in their response to oral debrisoquine.

The relation between dose, systemic availability, and response to oral debrisoquine was studied in 13 hypertensive patients receiving no other treatment. In 11 who received the same daily dose (40 mg) the fall in mean standing systolic blood pressure varied between 0-3 and 44-4 mm Hg. There was a ninefold difference in the daily urinary excretion and pre-dose plasma concentration of unchanged drug but an inverse correlation between daily urinary excretion of debrisoquine and its 4-hydroxy metabolite (r= -0-86), suggesting that a low recovery of debrisoquine occurs because of extensive metabolism.

Influence of intravenously administered ephedrine on splanchnic haemodynamics and clearance of lidocaine.

The effects of a 20 mg i.v. bolus of ephedrine sulphate on haemodynamics and plasma lidocaine concentrations were evaluated in eight volunteer subjects receiving a constant i.

Psychiatric and behavioral manifestations of normal pressure hydrocephalus. A case report and brief review.

Normal pressure hydrocephalus (NPH) may suggest its presence by behavioral symptoms. Initally, the symptoms often manifest themselves as depression with marked psychomotor retardation. Older patients without a prior psychiatric history who have soft, nonlocalizing neurological signs and fluctuating cognitive and memory deficits in association with prominent affective and/or psychotic symptomatology of recent onset, such as the case reported here, should raise the clinician's index of suspicion.

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.

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.

The interaction of radioiodinated thyrotropin with plasma membranes. Evidence for high affinity binding sites in the thyroid.

The binding of biologically active [125I]thyrotropin to purified plasma membranes prepared from bovine thyroid glands was studied. At 4 degrees C, specific binding reached a maximum after 2 h of incubation and a plateau was maintained for up to 20 h. Degradation of [125I]thyrotropin was undetectable after 2 h of incubation and was only 10% of the total after 20 h.

Survey of the development of laryngeal epithelium.

An overview of the developing laryngeal epithelium has been presented to establish the norm. The sequential relationships of the formation of the protective laryngeal covering, cellular and glandular, have been reviewed. The topographical distribution of the epithelial elements in the human larynx are illustrated in the adult and contrasted in the child.

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.

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.

Loose associations and disordered speech patterns in chronic schizophrenia.

The present research involves the development and utilization of a method to evaluate the free speech of chronic schizophrenic patients to measure aspects of thought disorder. Using this technique, two samples (one chronically hospitalized, the other nonhospitalized) of 15 chronic schizophrenic subjects each studied and compared. Severe types of looseness of association were not a prominent finding in the patients studied.

General derivation of the ideal intravenous drug input required to achieve and maintain a constant plasma drug concentration. Theoretical application to lignocaine therapy.

A constant plasma drug concentration can be achieved and maintained by the intravenous administration of an initial bolus loading dose in conjunction with a constant rate and an exponential intravenous drug infusion. The drug input required to achieve a constant plasma drug concentration is derived without making any assumptions about the nature of drug distribution within the body or elimination from the body.

Hemodynamic drug interaction: peridural lidocaine and intravenous ephedrine.

Hypotension following peridural anesthesia with lidocaine was treated by intravenous injection of ephedrine. The ephedrine relieved the cardiovascular depression, but was associated with a concomitant increase in plasma lidocaine concentrations. This increase may push the plasma lidocaine concentration into the toxic region.

General theory for rapidly establishing steady state drug concentrations using two consecutive constant rate intravenous infusions.

Steady state plasma drug concentrations can be achieved rapidly and safely by a drug input mode consisting of two consecutive constant rate intravenous infusions. A general method for calculating the relative rates of the two infusions is presented. The derivation is independent of the concepts of compartmental distribution and elimination of drugs within the body.