Pharmacokinetics of Phenobarbital in Microenema Via Macy Catheter Versus Suppository.
The oral route is compromised for nearly all patients approaching death. When agitation, seizures, or other intractable symptoms occur, a quick, discreet, comfortable, and effective alternate route for medication delivery that is easy to administer in the home setting is highly desirable.



To characterize the early absorption profile, variability, and comfort of phenobarbital given in microenema suspensions delivered via the Macy Catheter(®) (MC) vs. the same dose given via suppository.



This was a randomized, open-label, crossover study comparing the early absorption profile of equal doses of phenobarbital administered rectally in three treatment phases: phenobarbital suppository and two different microenemas with phenobarbital tablets crushed and suspended in 6 mL (MC-6) or 20 mL (MC-20) of tap water.



Mean plasma phenobarbital concentrations at 10 minutes were 12× higher for MC-20 and 8× higher for MC-6 compared to suppository. Concentrations achieved in 30 minutes via MC-20 took almost three hours to achieve with suppository. Mean AUC values were higher for MC-20 and MC-6 (82% and 46%, respectively) vs. suppository (P < 0.05). There was less variability in absorption for MC-20 and MC-6 (1.4- to 1.9-fold difference) compared to a 4.4-fold difference via suppository. MC administrations were reported as "not uncomfortable" compared to suppositories, which were reported as "mildly uncomfortable" (P < 0.05).



These results suggest phenobarbital oral tablets crushed and suspended in water and administered via the MC is superior to suppository in delivering the medication reliably and rapidly.
Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA. Electronic address: lamf@uthscsa.edu.
Y W Francis
YW
Lam
WCCT Global, Cypress, California, USA.
Ansom
A
Lam
Hospi Corporation, Newark, California, USA.
Brad
B
Macy
D000285:Administration, Rectal; D000328:Adult; D019540:Area Under Curve; D002404:Catheterization; D018592:Cross-Over Studies; D005260:Female; D017051:Hospice Care; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D008297:Male; D010634:Phenobarbital / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D013488:Suppositories; D055815:Young Adult
D006993:Hypnotics and Sedatives; D013488:Suppositories; D010634:Phenobarbital
Rectal administration; hospice care; phenobarbital; suppository