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Biomedical subjects

R Parini

Publications and source records attributed to R Parini.

25 records · Page 2Linked to original sources
PubMed1982

Influence of intrauterine maturation on the pharmacokinetics of amikacin in the neonatal period.

The effect of intrauterine maturation on amikacin disposition was studied in 29 preterm and term neonates. Mean gestational age (weeks) of the patients was 34.5 +/- 3.3 S.D. and their birth weight 1.980 +/- 920 g. After the last administration of the drug, amikacin decay was measured in plasma and urine for 100-250 h. The serum concentration versus time profiles were fitted by nonlinear regression analysis. The parameters of a 2- or 3-compartment model with elimination from the central compartment were calculated. Initial elimination T 1/2, volume of the central compartment, and steady state volume of distribution were significantly related to intrauterine maturation (respectively r = -0.76; -0.63; -0.57) whereas no significant linear correlation was found between clearance and gestational age (r = 0.19). Patients with gestational age less than 34 wk had a significantly reduced clearance when compared with the neonates with gestational age greater than 36 wk (0.78 +/- 0.17 versus 1.0 +/- 0.4 ml/h/kg, P less than 0.05). The ratio between the volumes of distribution showed that a higher amount of amikacin penetrates the peripheral compartments with increased gestational age. The renal clearance calculated in six patients averaged 66% of the total body clearance, suggesting that elimination of the drug can occur in the neonate via nonrenal routes. Analysis of the long term urinary elimination of amikacin showed that about 5% of the total amount of the drug administered in 5-8 days of treatment is retained in the organism. Although quantitatively small, this amount is relevant for the potential nephrotoxicity of the drug.

Amikacin↗
PubMed1982

Evaluation of the renal and auditory function of neonates treated with amikacin.

35 neonates (mean gestational age: 34.9 +/- (SD) 3.5 weeks; mean birth weight: 2,180 +/- 890 g) treated with amikacin were examined for possible ototoxicity and nephrotoxicity. Audiometric tests were performed at 14.2-30.0 months postconceptional age by cross-checking behavioural with brain stem-evoked response audiometry. Only 1 infant was found with a mild hearing loss with brain stem audiometry, which, however, could not be attributed to amikacin with certainty. The effect of the aminoglycoside on the kidney was studied both by monitoring serum creatinine and the urinary elimination of the lysosomal enzyme N-acetylglucosaminidase (NAG). No significant difference was found in serum creatinine between the group under investigation and a control group of untreated premature neonates. A transient elevation was found in NAG urinary excretion in the neonates treated with amikacin. These results lead to the conclusion that amikacin at the recommended dosages (7.5 mg/kg every 12 h) causes a subclinical and reversible tubular damage in the neonate despite the high serum concentrations of the drug. The clinical relevance of this finding is discussed.

Acetylglucosaminidase↗
PubMed1981

Theophylline distribution in the premature neonate.

Theophylline (T) tissue distribution was studied in 11 premature newborns treated with T for prematurity apnea, who had died from severe pathology. To investigate the pattern of distribution of T, in particular the role of the blood-brain barrier in this period of life, two animal species were employed (rat and guinea pig), differing widely in their postnatal development. T was administered to the animals acutely and chronically and the resulting data were compared to human findings. In human prematures no specific accumulation and a wide variety in tissue concentrations, as in tissue/blood ratios, were observed. In the rat, unlike the guinea pig, brain/blood ratios of T concentration declined as postnatal age rose, suggesting that development of the blood-brain barrier plays a major role.

Aging↗
PubMed1981

Theophylline metabolism during the first month of life and development.

The metabolic pathway of theophylline (T) was studied in 12 newborns, one young infant, six children, and three adult volunteers. T was injected IV, and blood and urine samples were assayed for T, caffeine (C), and their metabolites by a high-pressure liquid chromatography technique. We confirmed the methylation of T to C in newborn infants but not in older subjects. Demethylation of T to 3-methylxanthine was found in the young infant, in children, and in adults, but not in newborns. The major products excreted by neonates were T, 1-methyluric acid, and 1,3-dimethyluric acid. Children excreted a larger fraction of methyluric acids than adults. Renal and body clearance of T and C are reported and discussed in relation to the age.

Adult↗
PubMed1980

Plasma glutamic acid levels in premature newborn.

24 premature, newborn infants were investigated for plasma glutamic acid (GA) levels before and after a normal milk feed, to ascertain if the ingestion of GA present in the milk could result in an increase of its plasma level. No increases were detected in plasma between 5 and 90 min after the feed. These results may be important in respect to the problem of the possible toxicity of monosodium glutamate (MSG) added to baby foods.

Animals↗
PubMed1980

Multiexponential elimination of gentamicin. A kinetic study during development.

The long-term disposition of gentamicin (up to 100-240 h) was studied in 13 premature newborns (33 weeks mean gestational age) and in 7 infants and children (1 month to 8 years). The data fitted bi- or triexponential curves with terminal half-lives averaging 51 and 37 h. Newborns showed lower values of body clearance, central compartment and steady state volumes of distribution than infants and children (respectively, 12.8 vs. 50.4 ml/min/1.73 m2, 9.03 vs. 17.5 liters/1.73 m2, and 15.7 vs. 35.5 liters/1.73 m2). The ratio between the amount of gentamicin predicted at steady state in the tissue compartment and in the total body was also significantly lower in newborns than in the older group (0.4 vs. 0.52). These data provide pharmacokinetic demonstration of an age dependence in gentamicin tissue distribution and excretion during the early stages of human development.

Adult↗