ABSTRACT
BACKGROUND: Recently, sildenafil was introduced to treat pulmonary arterial hypertension (PAH); however, there are currently few studies on the pharmacokinetics of sildenalfil in children. Therefore, we aimed to carry out a pharmacokinetic study of sildenafil in children with PAH using a single dose. METHODS: Twelve children diagnosed with PAH, consisting of with ten males and two females, were recruited for the study after obtaining written consent from their parents or guardians. Blood samples were obtained predose and at 0.25, 0.5, 1, 2, 4, 8 and 12 hours after the oral administration of 1 mg/kg of sildenafil using an extemporal pediatric formulation developed in our laboratory. The samples were analyzed using a previously validated high performance liquid chromatography method. RESULTS: A pharmacokinetic analysis using the WinNonlin 3.1 program that considered the Akaike information criterion (AIC) for selecting a more adjustable model was performed. The following pharmacokinetic parameters were obtained: maximal concentration (Cmax): 366±179 ng/mL, time to maximal concentration: 0.92±0.30 hours, elimination half-life (t1/2): 2.41±1.18 hours, total clearance (CLtot/F): 5.85±2.81 L/hour, volume of distribution (Vd/F): 20.13±14.5 L, absorption rate constants (Ka): 0.343 hour-1, elimination rate (Ke): 0.35 hour-1, area under curve from zero to infinity: 2061±618 ng/mL/hour. The data of all patients adjusted to the model of one compartment were corroborated using AIC. CONCLUSIONS: The parameters Ka, Ke and t1/2 were found to be similar to those reported in adults; however, the values of Cmax and Vd/F were significantly higher. Based on these findings, we propose that treatment regimen of sildenafil be adjusted in children with PAH.
Subject(s)
Hypertension, Pulmonary/blood , Hypertension, Pulmonary/drug therapy , Sildenafil Citrate/pharmacokinetics , Vasodilator Agents/pharmacokinetics , Administration, Oral , Adolescent , Age Factors , Anthropometry , Biological Availability , Child , Child, Preschool , Cohort Studies , Dose-Response Relationship, Drug , Drug Administration Schedule , Female , Humans , Hypertension, Pulmonary/diagnosis , Male , Mexico , Prospective Studies , Severity of Illness Index , Sex Factors , Sildenafil Citrate/administration & dosage , Vasodilator Agents/administration & dosageABSTRACT
In this study, we have identified and evaluated the cardiovascular anomalies associated with Williams-Beuren syndrome in children.In a retrospective, lineal, and observational study, we reviewed the files of children who were seen from 1980 through 2005 (25 years) after a clinical diagnosis of Williams-Beuren syndrome.Forty children were diagnosed with this syndrome at the National Institute of Pediatrics in Mexico City. Of these, 32 (80%) were found to have congenital heart defects. The male-to-female ratio was 1.3:1 and ages ranged from 6 months to 15 years (mean, 4.4 years) at the time of diagnosis. All of the patients had morphologic and genetic characteristics typical of the syndrome.We emphasize the cardiovascular aspects from a clinical point of view. Supravalvular aortic stenosis was our most frequent finding, in 18 of 32 patients (56%); gradient differences in these patients ranged from 14 to 81 mmHg. Five patients showed combined lesions, the most frequent being supravalvular aortic stenosis in combination with pulmonary artery brachial stenosis, or with atrial and ventricular defects. Patients with incomplete atrioventricular defect and bicuspid aortic valve, as were seen at our hospital, have not to our knowledge been reported in other studies.One of the patients was scheduled for balloon dilation; another was scheduled for surgery; a 3rd patient was operated on twice for the placement of an aorto-aortic bridge; another underwent ventricular septal defect closure; and yet another underwent aortoplasty, this last dying shortly after surgery.
