Prostin VR Pediatric
"The U.S. Food and Drug Administration today approved TOBI Podhaler (tobramycin inhalation powder) for the management of cystic fibrosis
Cystic fibrosis is a genetic disease that affects about 30,000 pediatric and adult patients in the United "...
Prostin VR Pediatric
Prostin VR Pediatric Sterile Solution
Alprostadil (prostaglandin E1) is one of a family of naturally occurring acidic lipids with various pharmacologic effects. Vasodilation, inhibition of platelet aggregation, and stimulation of intestinal and uterine smooth muscle are among the most notable of these effects. Intravenous doses of 1 to 10 micrograms of alprostadil per kilogram of body weight lower the blood pressure in mammals by decreasing peripheral resistance. Reflex increases in cardiac output and rate accompany the reduction in blood pressure.
Smooth muscle of the ductus arteriosus is especially sensitive to alprostadil, and strips of lamb ductus markedly relax in the presence of the drug. In addition, administration of alprostadil reopened the closing ductus of new-born rats, rabbits, and lambs. These observations led to the investigation of alprostadil in infants who had congenital defects which restricted the pulmonary or systemic blood flow and who depended on a patent ductus arteriosus for adequate blood oxygenation and lower body perfusion.
In Infants with restricted pulmonary blood flow, about 50% responded to alprostadil infusion with at least a 10 torr increase in blood pO2 (mean increase about 14 torr and mean increase in oxygen saturation about 23%). In general, patients who responded best had low pretreatment blood pO2 and were 4 days old or less.
In infants with restricted systemic blood flow, alprostadil often increased pH in those having acidosis, increased systemic blood pressure, and decreased the ratio of pulmonary artery pressure to aortic pressure.
Alprostadil must be infused continuously because it is very rapidly metabolized. As much as 80% of the circulating alprostadil may be metabolized in one pass through the lungs, primarily by beta- and omega-oxidation. The metabolites are excreted primarily by the kidney, and excretion is essentially complete within 24 hours after administration. No unchanged alprostadil has been found in the urine, and there is no evidence of tissue retention of alprostadil or its metabolites.
Pharmacokinetics in Special Populations
Pediatric: Alprostadil plasma concentrations were measured in 10 neonates (gestational age of 34 weeks in 2 infants and 38 to 40 weeks in 8 infants) receiving steady-state intravenous infusions of alprostadil to treat underlying cardiac malformations. Infusion rates of alprostadil ranged from 5 to 50 (median, 45) nanograms/kilogram/minute, resulting in alprostadil plasma concentrations ranging between 22 and 530 (median, 56) picograms/milliliter. The wide range of alprostadil plasma concentrations in neonates reflects high variability in individual clearances of alprostadil in this patient population.
Gender: The potential influence of gender on the pharmacokinetics of alprostadil has not been formally studied in healthy subjects. Two studies determined the pulmonary extraction of alprostadil following intravascular administration in 23 patients with ARDS. The mean (±SD) pulmonary extraction was 66% ± 20% in 17 male patients and 69% ± 18% in 6 female patients, suggesting that the pharmacokinetics of alprostadil are not influenced by gender.
Race: The potential influence of race on the pharmacokinetics of alprostadil has not been formally evaluated.
Pulmonary first-pass metabolism is the primary factor influencing the systemic clearance of alprostadil. Although the pharmacokinetics of alprostadil have not been formally examined in patients with renal or hepatic insufficiency, alterations in renal or hepatic function would not be expected to have a major influence on the pharmacokinetics of alprostadil.
The pulmonary extraction of alprostadil following intravascular administration was reduced by 15% (66 ± 32% vs 78 ± 2.4%) in patients with ARDS compared with a control group of patients with normal respiratory function who were undergoing cardiopulmonary bypass surgery. Pulmonary clearance was found to vary as a function of cardiac output and pulmonary intrinsic clearance in a group of 14 patients with ARDS or at a risk of developing ARDS following trauma or sepsis. In this study, the extraction efficiency of alprostadil ranged from subnormal (11%) to normal (90%), with overall mean of 67%.
Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.
Additional Prostin VR Pediatric Information
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Find out what women really need.