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Biomedical subjects

M Contin

Publications and source records attributed to M Contin.

60 records · Page 4Linked to original sources
PubMed1984

Stereoselective binding of propranolol enantiomers to human alpha 1-acid glycoprotein and human plasma.

The binding of propranolol enantiomers to human albumin (ALB), alpha 1-acid glycoprotein (alpha 1-AGP) and plasma was studied. (-) propranolol is more bound than (+)propranolol to alpha 1-AGP (P less than 0.001) and to plasma (P less than 0.05). In solutions containing ALB at a constant concentration (580 mumol/l) and alpha 1-AGP at increasing concentrations, the binding of both isomers increases but the stereo selectivity is evident throughout the alpha 1-AGP concentration range examined (25-100 mumol/l).

Adult↗
PubMed1984

Diurnal fluctuations in free and total steady-state plasma levels of carbamazepine and correlation with intermittent side effects.

The relationship between diurnal fluctuations in free (unbound) and total plasma carbamazepine levels and the appearance of intermittent side effects was investigated in nine epileptic patients receiving chronic therapy with carbamazepine, alone or in combination with phenobarbital. On a three-times-daily or four-times-daily dosing schedule, both total and free carbamazepine levels fluctuated considerably (on an average, 41 and 45%, respectively, around the mean). Side effects (particularly diplopia and nystagmus) were observed in five patients and showed an intermittent pattern in four. Side effects were never found at total carbamazepine levels less than 34 mumol/L but invariably appeared at levels greater than 38 mumol/L. At levels between 34 and 38 mumol/L adverse effects were inconsistently observed. The correlation between plasma carbamazepine levels and manifestations of toxicity was slightly stronger when free rather than total levels were considered. Side effects were always apparent at free levels greater than 7.2 mumol/L. These data underline the limitations of relying on a single drug level determination during the monitoring of carbamazepine therapy and emphasize the necessity of carefully adjusting the dosing schedule, to minimize the appearance of intermittent adverse effects.

Adolescent↗
PubMedDate not supplied

Free and total serum concentrations of carbamazepine and carbamazepine-10,11-epoxide in infancy and childhood.

Total and free serum concentrations of carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-E) at steady state were determined in 10 infants (ages 4-13 months), 10 preschool children (ages 3-5 years), and 11 school children (ages 7-11 years) receiving equivalent doses of CBZ alone. Free and total CBZ levels tended to increase with increasing age, while CBZ-E levels did not show any significant age dependency. As a result, CBZ-E/CBZ ratios were higher in infants and preschool children than in the older age group. The degree of plasma protein binding of CBZ and CBZ-E did not show any important differences among the various groups. These data provide evidence that, within a pediatric population, CBZ shows age-related dispositional changes which may be clinically important.

Age Factors↗
PubMedDate not supplied

Free concentration of carbamazepine and carbamazepine-10,11-epoxide in children and adults. Influence of age and phenobarbitone co-medication.

Total and free plasma concentrations of carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-E) were determined in 39 children (aged 3 to 10 years) and 79 adults (aged 15 to 65 years) receiving long term treatment with CBZ alone or in combination with phenobarbitone (PB). Compared with the corresponding age groups treated with CBZ alone, adults and children receiving PB co-medication showed lower total and free CBZ concentrations, similar CBZ-E concentrations and higher CBZ-E/CBZ ratios. Among patients on CBZ alone, children had at any given dose lower total and free CBZ and CBZ-E concentrations than adults. Lower CBZ levels in children than in adults were also found among patients receiving phenobarbitone in combination. CBZ-E/CBZ ratios did not differ significantly between children and adults. These data provide evidence that children show an elevated free CBZ clearance with a metabolic pattern different from that observed during phenobarbitone induction.

Adult↗
PubMedDate not supplied

Concentration-effect relationship of levodopa-benserazide dispersible formulation versus standard form in the treatment of complicated motor response fluctuations in Parkinson's disease.

We compared the kinetic-dynamic profile of a postprandial dose of levodopa-benserazide dispersible formulation to that of the standard form in eight patients with parkinsonism presenting delayed or irregular patterns of after-meal levodopa dose effects. Patients were studied on two occasions, one week apart, according to an intra-subject randomized cross-over design. Thirty minutes after the consumption of a standard meal, patients received their usual levodopa-benserazide postprandial dose, on one occasion in the standard formulation and on the other one in the dispersible form. Blood venous samples for analysis of plasma levodopa concentrations were drawn at 15-minute intervals for the first 2 hours, then half-hourly until 5 hours after dosing. Motor response to the levodopa test dose was assessed by the finger tapping test at the same times as blood was sampled. The only statistically significant finding was a shorter time to peak plasma levodopa concentration with the levodopa-benserazide dispersible formulation compared with the standard form, whereas comparisons of levodopa pharmacodynamics showed little advantage of either formulation. Considering that liquid formulations of levodopa are less practical, we suggest reserving dispersible levodopa-benserazide tablets for selected patients and carefully monitoring drug dose motor response.

Aged↗