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[Rectal absorption of phenobarbital in children as affected by different vehicles]
Insights
Rectal administration of phenobarbital in infants showed faster absorption rates when using sodium-phenobarbital and suppositories with lower melting points. Vehicle hydroxyl values also influenced absorption speed, with an overall rectal absorption ratio of 74%.
Area of Science:
- Pediatric Pharmacology
- Pharmaceutics
- Drug Delivery Systems
Background:
- Phenobarbital is a common anticonvulsant used in infants.
- Rectal administration is a viable route for pediatric drug delivery.
- Optimizing rectal absorption is crucial for effective phenobarbital therapy in neonates.
Purpose of the Study:
- To evaluate the impact of different suppository bases and drug formulations on phenobarbital rectal absorption in infants.
- To determine the influence of suppository melting point and hydroxyl values on absorption kinetics.
- To compare the bioavailability of rectally administered phenobarbital with intravenous administration.
Main Methods:
- Sixty-eight infants received phenobarbital or sodium-phenobarbital (7-15 mg/kg) via suppositories with varying melting points and hydroxyl values (Witepsol H 12, W 35, E 76).
- Serum concentrations were analyzed using kinetic analysis.
- Bioavailability was assessed by comparing the area under the serum concentration curve (AUC) after rectal and intravenous administration in a subset of 8 infants.
Main Results:
- Rectal absorption rate was significantly higher with sodium-phenobarbital compared to phenobarbital.
- Suppositories with lower melting points (32.5°C) resulted in faster absorption than those with higher melting points (37.5°C).
- Increased hydroxyl values in the suppository vehicle accelerated phenobarbital absorption.
- The mean absorption ratio (bioavailability) after rectal administration compared to intravenous was 74%.
Conclusions:
- Sodium-phenobarbital formulation and suppository characteristics (melting point, hydroxyl value) significantly affect rectal absorption rates in infants.
- Lower melting point suppositories and those with higher hydroxyl values enhance phenobarbital absorption.
- Rectal administration of phenobarbital offers substantial bioavailability, making it an effective delivery route in pediatric patients.
Abstract:
68 infants received 7--15 mg phenobarbital and sodium-phenobarbital/kg body weight by suppositories of different melting-points and hydroxyl-values (Witepsol H 12, W 35, E 76). The kinetic analysis of the serum concentration curve shows that the rate of rectal absorption is significantly increased if sodium-phenobarbital instead of phenobarbital is applied. The absorption rate is faster using suppositories with a lower melting-point (32.5 degrees C) compared to suppositories with a higher one (37.5 degrees C). Increasing the amount of hydroxyl values in the vehicle the absorption rate of phenobarbital becomes faster. Comparing the area under the serum concentration curve after intravenous and rectal application in 8 infants the absorption ratio was 74%.