PMID- 24692764
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20140402
LR  - 20211021
IS  - 0011-393X (Print)
IS  - 0011-393X (Linking)
VI  - 68
IP  - 5
DP  - 2007 Sep
TI  - Steady-state serum phenytoin concentrations after nasogastric tube administration 
      of immediate-release phenytoin tablets and extended-release phenytoin capsules: 
      an open-label, crossover, clinical trial.
PG  - 325-37
LID - 10.1016/j.curtheres.2007.10.007 [doi]
AB  - BACKGROUND: When phenytoin is prescribed for administration via nasogastric tube, 
      immediate-release OR) phenytoin tablets are crushed before use and 
      extended-release (ER) phenytoin capsules are opened and only the granules are 
      used. However, it is unknown whether the same dose of these 2 different 
      formulations will result in the same steady-state serum phenytoin concentration. 
      OBJECTIVE: The aim of this study was to determine whether ER phenytoin capsules 
      can be used interchangeably with IR phenytoin tablets for prophylaxis of 
      posttraumatic seizures. METHODS: Inpatients at the neurosurgical ward at Prasat 
      Neurological Institute, Bangkok, Thailand, between October 2004 and October 2005 
      were enrolled in the study. All patients were initially prescribed IR phenytoin 
      tablets 300 mg/d as a maintenance dose for prophylaxis of posttraumatic seizures. 
      The serum phenytoin concentration was measured after >/=5 days of treatment with IR 
      phenytoin tablets 300 mg/d (two 50-mg tablets every 8 hours) that had been 
      crushed before being administered concomitantly with a blenderized diet through 
      the nasogastric tube. Without a washout period, the dosage form was changed to ER 
      phenytoin capsules (three 100-mg capsules QD). The capsules were opened and the 
      contents were administered concomitantly with the blenderized diet through the 
      nasogastric tube for >/=5 days. The serum phenytoin concentration was again 
      determined. The patients were closely monitored for seizures and adverse events 
      (AEs). RESULTS: Thirty-three patients enrolled in the study and 17 (10 women, 7 
      men; mean [SD] age, 62.94 [15.94] years [range, 18-89 years]) completed the 
      study. The mean (SD) serum phenytoin concentrations after administration of 
      phenytoin tablets and capsules were 6.03 (5.92) mug/mL and 3.80 (2.71) mug/mL, 
      respectively (P = 0.019). The mean serum phenytoin concentrations, adjusted for 
      low serum albumin concentrations after administration of tablets and capsules, 
      were calculated and reported to be 10.33 (11.60) mug/mL and 6.28 (4.76) mug/mL, 
      respectively (P = 0.035). The maximum phenytoin metabolic rate (Vmax) (assuming 
      the substrate concentration at which the rate of metabolism is one half Vmax = 4 
      mg/L) after the administration of phenytoin tablets and capsules was 8.37 (2.42) 
      mg/kg . d(-1) and 10.38 (6.48) mg/kg . d(-1), respectively. These values were not 
      significantly different. All patients were seizure-free and no AEs were observed. 
      CONCLUSION: The steady-state serum phenytoin concentration was significantly 
      lower with ER phenytoin capsules 300 mg/d than IR phenytoin tablets 300 mg/d 
      administered via nasogastric feeding tube concomitantly administered with a 
      blenderized diet in these neurosurgical patients. Key words: phenytoin 
      nasogastric tube feeding extended-release capsule immediate-release tablet.
FAU - Panomvana, Duangchit
AU  - Panomvana D
AD  - Department of Pharmacy (Clinical), Faculty of Pharmaceutical Sciences, 
      Chulalongkorn University, Bangkok, Thailand.
FAU - Khummuenwai, Napanan
AU  - Khummuenwai N
AD  - Department of Pharmacy (Clinical), Faculty of Pharmaceutical Sciences, 
      Chulalongkorn University, Bangkok, Thailand.
FAU - Sra-Ium, Supasil
AU  - Sra-Ium S
AD  - Department of Pharmacy, Ramathibodi Hospital, Bangkok, Thailand.
FAU - Towanabut, Somchai
AU  - Towanabut S
AD  - Department of Medicine, Neurological Institute, Bangkok, Thailand.
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Curr Ther Res Clin Exp
JT  - Current therapeutic research, clinical and experimental
JID - 0372621
PMC - PMC3969937
EDAT- 2007/09/01 00:00
MHDA- 2007/09/01 00:01
PMCR- 2007/09/01
CRDT- 2014/04/03 06:00
PHST- 2007/06/11 00:00 [accepted]
PHST- 2014/04/03 06:00 [entrez]
PHST- 2007/09/01 00:00 [pubmed]
PHST- 2007/09/01 00:01 [medline]
PHST- 2007/09/01 00:00 [pmc-release]
AID - S0011-393X(07)00088-4 [pii]
AID - 10.1016/j.curtheres.2007.10.007 [doi]
PST - ppublish
SO  - Curr Ther Res Clin Exp. 2007 Sep;68(5):325-37. doi: 
      10.1016/j.curtheres.2007.10.007.