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Biomedical subjects

A Baruzzi

Publications and source records attributed to A Baruzzi.

At least 73 records · Page 4Linked to original sources
PubMed1989

Increased dosage of carbidopa in parkinsonian patients on low carbidopa-levodopa regimen. Effect on levodopa bioavailability.

The effect of a 2.5-fold increase in daily carbidopa intake on the bioavailability of levodopa was studied in six patients with Parkinson's disease on a low chronic regimen of carbidopa-levodopa (Sinemet) at the fixed ratio of 1:10. The extent of levodopa absorption, expressed as the area under the 11-h plasma levodopa concentration-time curve (AUC0-11 h), was not enhanced by the higher carbidopa dose. A significant increase in the AUC was found for the levodopa metabolite 3-O-methyldopa at the higher carbidopa intake. Clinical performances of individual patients were identical with both carbidopa-levodopa ratios. From these data, an adequate inhibition of peripheral decarboxylation and hence a good bioavailability of levodopa may be expected in patients taking low doses of carbidopa-levodopa, using currently available commercial preparations.

Aged↗
PubMed1988

Carbamazepine and phenytoin. Comparison of cognitive effects in epileptic patients during monotherapy and withdrawal.

We compared the cognitive effects of carbamazepine and phenytoin with neuropsychological tests exploring intelligence, vigilance, attention, memory, and visuomotor performances in 25 epileptics (13 receiving carbamazepine and 12 receiving phenytoin) and 26 matched normal controls. Patients were seizure free for at least two years and taking prolonged monotherapy. We also evaluated the effects of drug withdrawal by retesting patients three months after reduction at half drug dose and three months and one year after complete withdrawal. Our findings suggest that phenytoin affects the cognitive functions more than carbamazepine does, although the negative effects of both drugs are reversible by complete therapy withdrawal.

Carbamazepine↗
PubMed1988

Neuroendocrinological evidence of an anti-dopaminergic effect of flunarizine.

The effect of a one month treatment with flunarizine (5 mg/day) on pituitary responsiveness to gonadotrophin-releasing hormone (GnRH), thyrotrophin-releasing hormone (TRH) and arginine infusion was assessed in 17 adolescents (11 M, 6 F) treated with the drug to prevent migraine attacks. Basal prolactin concentrations as well as the prolactin response to TRH were significantly (p less than 0.05) increased after flunarizine treatment. Flunarizine had no effect on the folliclestimulating and luteinising hormone response to GnRH stimulation, growth hormone response to arginine infusion or thyrotrophin response to TRH stimulation. Our data suggest that flunarizine may interfere with the hypothalamic-pituitary-prolactin axis decreasing dopaminergic inhibitory tonus.

Adolescent↗
PubMed1987

Simple and rapid GLC method for the determination of orphenadrine in human plasma.

A rapid and specific method has been developed for the determination of orphenadrine concentration in plasma. It involves a one-step sample preparation using n-hexane/isopropyl alcohol (98:2) extraction, and analysis by gas chromatography on a wide bore capillary column using nitrogen/phosphorus detection. This procedure considerably simplifies previously reported assays and is specific and sensitive enough for the determination of orphenadrine in plasma of patients on chronic therapy.

Chromatography, Gas↗
PubMed1987

Influence of meal ingestion time on pharmacokinetics of orally administered levodopa in parkinsonian patients.

The influence of meal ingestion time on rate and extent of oral levodopa absorption was evaluated in a group of 17 patients, after administration of their usual second daily dose of levodopa plus carbidopa (Sinemet 10:1) or benserazide (Madopar 4:1). Standard meals were consumed by the patients after they had fasted 15-17 h, on one occasion 30 min before ingestion of the levodopa "study dose" and, at another time, 2 h after ingestion of the same dose. This study dose, ranging from 50 to 250 mg levodopa, was given to the patients at 11 a.m., 4 h after their first morning dose. Time to peak plasma levodopa concentration increased threefold (from 45 +/- 23 to 134 +/- 76 min, p less than 0.001), when levodopa was administered after meals. Area under the 6-h plasma concentration-time curve for levodopa was decreased in 10 subjects, unchanged in three and higher in four after ingestion of meals, the latter finding probably resulting from an erratic absorption even at fasting. On the whole, levodopa absorption proved significantly lower (p less than 0.01), on the average 15%. Similarly, peak plasma levodopa concentrations were lower in 12 patients, unchanged in two, and higher in three, with an overall significant decrease (p less than 0.001) of 30% on the average. The data confirm the importance of meal ingestion time in relation to levodopa dose as a determinant of drug absorption.

Aged↗
PubMed1986

Altered serum protein binding of carbamazepine in disease states associated with an increased alpha 1-acid glycoprotein concentration.

The protein binding of carbamazepine (CBZ) in vitro was assessed in sera from 47 patients with various diseases known to alter alpha 1-acid glycoprotein (AAG) concentration and from 20 drug-free normal control subjects. In the patient group, AAG and albumin (HSA) concentrations ranged from 6 to 74 mumol/l and from 377 to 652 mumol/l, respectively; in the controls, protein concentrations were less variable, ranging from 11 to 26 mumol/l for AAG and from 623 to 754 mumol/l for HSA. In both the patient and the combined patient and control groups, free CBZ fractions were inversely correlated with the serum AAG concentration (r = -0.62). No significant relationship could be found between the free CBZ fraction and the serum HSA concentration. The free CBZ fraction was moderately but significantly decreased in patients with AAG levels above 26 mumol/l (the highest value found in controls) as compared either to patients with a normal AAG concentration or to control subjects (19 +/- 5% vs 23 +/- 4% and 23 +/- 2%), despite the finding of a higher HSA concentration in the control group. The data confirm AAG as an important determinant of interindividual variability in serum CBZ binding.

Adult↗
PubMed1986

L-5-hydroxytryptophan versus placebo in childhood migraine prophylaxis: a double-blind crossover study.

L-5HTP was tested versus placebo in a double-blind crossover study of 27 migraine children aged 6-12 years, who recorded their headaches in a headache diary for 1 month. Twenty-one patients subsequently started the trial. The mean daily dose of L-5HTP was 5 mg/kg body weight, and each treatment period with either L-5HTP or placebo lasted 12 weeks. In group A (L-5HTP-placebo; 10 patients) and group B (placebo-L-5HTP; 11 patients) both L-5HTP and placebo led to a significant reduction of the migraine index and frequency of migraine attacks during the 3rd month of each treatment period. However, we found a treatment X period interaction because the efficacy determinants decreased significantly during the first and the second treatment periods in both groups irrespective of the sequence of treatments. No differences were found between L-5HTP (first period of group A) and placebo (first period of group B).

Child↗
PubMed1986

Withdrawal of phenobarbital and carbamazepine in epileptic patients: a preliminary neuropsychological report.

We systematically investigated the neuropsychological effects of controlled withdrawal of antiepileptic therapy with a battery of tests exploring intelligence, vigilance, attention, memory and sensori-motor performance. 16 patients without seizures for at least 2 years, 9 on therapy with phenobarbital (PB) and 7 with carbamazepine (CBZ), were examined 4 times over a period of 21 months. No significant correlation was found between drug levels and performance in the tests. The slight differences found between the PB and CBZ groups at full doses disappeared completely one year after withdrawal.

Adolescent↗
PubMed1985

Propranolol plasma levels and relief of migraine. Relationship between plasma propranolol and 4-hydroxypropranolol concentrations and clinical effects.

The relationship between propranolol and 4-hydroxypropranolol plasma concentrations and relief of migraine was assessed in 17 patients during treatment with oral racemic propranolol hydrochloride in doses of 40 to 240 mg/day. Propranolol decreased the migraine index more than 70% in 13 patients: five patients at a dosage of 40 mg/day, five patients at a dosage of 120 mg/day, and three patients at a dosage of 240 mg/day. Three patients did not achieve a good improvement of migraine at any of the doses used. The relief of migraine was not directly related to the propranolol and 4-hydroxypropranolol plasma concentrations.

Adult↗
PubMed1985

Alpha 1-acid glycoprotein concentration and serum protein binding of carbamazepine and carbamazepine-10,11 epoxide in children with epilepsy.

The relationship between the serum protein binding of carbamazepine (CBZ) and carbamazepine-10,11 epoxide (CBZ-E) and the concentration of alpha 1-acid glycoprotein (AAG) and albumin (HSA) was examined in 39 CBZ-treated epileptic children aged 4 months to 12 years. A significant inverse correlation was found between the free fraction of both compounds and serum AAG, even though changes in AAG concentration explained only part of the variation in binding. No correlation was found between the free fraction of CBZ and CBZ-E and HSA, probably due to the small intersubject variation in HSA concentration. In vitro experiments showed that both CBZ and CBZ-E were bound to HSA and to a lesser extent to AAG. At equivalent HSA concentrations, the binding of CBZ and its metabolite increased proportionately with increasing AAG concentration within the range occurring clinically.

Carbamazepine↗
PubMed1985

Determination of total and free plasma carbamazepine concentrations by enzyme multiplied immunoassay: interference with the 10,11-epoxide metabolite.

The performance of the enzyme multiplied immunoassay technique (EMIT) in the measurement of total and free plasma carbamazepine (CBZ) levels was assessed in 140 clinical specimens and compared with a reference high pressure liquid chromatography (HPLC) technique. Free drug was measured in plasma filtrates obtained by the Free Level system. Both total and free CBZ levels as determined by EMIT correlated strongly with corresponding HPLC values (r = 0.88 and 0.92, respectively). Plasma CBZ concentrations, however, were higher by EMIT than by HPLC. The degree of CBZ overestimation by EMIT was relatively small (about 14%) in whole plasma but quite considerable (35% on average) in the filtrates. As a result, estimated values of free CBZ fraction were also higher for EMIT than for HPLC. Separate experiments in vitro suggested that the discrepancies between the two methods were due to cross-reaction of the EMIT reagent with the 10,11-epoxide metabolite of CBZ. The greater degree of overestimation for the free drug can be explained by the higher proportion of less protein-bound metabolite in the filtrates. These results need to be taken into account in the interpretation of free CBZ level data from laboratories using different techniques.

Carbamazepine↗