Biomedical subjects

S R Burrow

Publications and source records attributed to S R Burrow.

3 recordsLinked to original sources

PubMed1979

Phenytoin cumulation kinetics.

Four male subjects were given phenytoin orally in single or twice-daily doses. Subjects were on 2 or 3 different dosing rates from 260 to 600 mg phenytoin sodium daily. Predose blood samples were obtained almost daily. The resulting serum levels, measured by gas-liquid chromatography, ranged from 1 to 18 micrograms/ml. Serum phenytoin concentration-time data were fit to a 1-compartment open model with zero-order input and Michaelis-Menten elimination. The resulting computer-generated parameter estimates (Vmax, 5.28 to 8.41 mg/kg/day; Km, 0.83 to 4.18 mg/1; Vd, 0.74 to 0.97 1/kg) are in agreement with the ranges of values in the literature. The time course of phenytoin cumulation is compatible with the presence of a major elimination pathway exhibiting Michaelis-Menten kinetic behavior.

Administration, Oral↗

PubMed1978

Dose-dependent pharmacokinetic behavior of lidocaine in the conscious dog.

The apparent steady state blood concentration of lidocaine in dogs depends on the animal's lidocaine treatment history. For example, an infusion of 50 microgram/Kg/min X 240 min followed immediately by an infusion of 125 microgram/Kg/min X 240 min yields steady state lidocaine levels which are consistent with a linear drug dispositional system. However, when the sequence of these infusions is reversed the apparent steady state level during the low infusion rate step is much greater than those predicted from the steady state level observed during the high infusion rate (assuming a linear dispositional model). These data suggest that high dose lidocaine infusion treatment alters the dog's ability to clear lidocaine during a subsequent low infusion rate treatment period.

Animals↗

PubMedDate not supplied

Bupivacaine and other amide local anesthetics inhibit the hydrolysis of chloroprocaine by human serum.

The rate of hydrolysis of chloroprocaine by human serum was studied in the presence and absence of a number of aminde local anesthetics and their metabolites. Bupivacaine (2.4 microgram/ml) and etidocaine (2.3 microgram/ml) caused 38% and 21% inhibition respectively of the rate of chloroprocaine hydrolysis. Circulating concentrations of these drugs have been reported in this range by several investigators following epidural doses of 150 to 400 mg of either drug. Mepivacaine, lidocaine, and two lidocaine metabolites (glycine xylidide and monoethylglycine xylidide) were only inhibitory at levels much greater than those seen in blood following the usual local anesthetic doses of the parent compounds. Since serum is an important site of chloroprocaine metabolism in man, the probability of chloroprocaine intoxication may be increased when it is administered with local anesthetics such as bupivacaine and etidocaine.

Anesthetics, Local↗