Drug Interaction Report
3 potential interactions and/or warnings found for the following 2 drugs:
- Antinaus 50 (promethazine)
- Phenytoin Sodium, Extended Release (phenytoin)
Interactions between your drugs
phenytoin promethazine
Applies to: Phenytoin Sodium, Extended Release (phenytoin), Antinaus 50 (promethazine)
MONITOR: Concurrent use of phenothiazines and phenytoin may increase the effect of phenytoin and decrease the effect of the phenothiazine. The mechanism is unknown and clinical data have been inconsistent.
MANAGEMENT: Close monitoring for clinical and laboratory evidence of phenytoin toxicity is indicated. Patients should be advised to notify their physician if they experience symptoms of possible hydantoin toxicity, including drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia.
References
- Houghton GW, Richens A (1975) "Inhibition of phenytoin metabolism by other drugs used in epilepsy." Int J Clin Pharmacol, 12, p. 210-6
- Vincent FM (1980) "Phenothiazine-induced phenytoin intoxication." Ann Intern Med, 93, p. 56-7
- Haidukewych D, Rodin EA (1985) "Effect of phenothiazines on serum antiepileptic drug concentrations in psychiatric patients with seizure disorder." Ther Drug Monit, 7, p. 401-4
- Linnoila M, Viukari M, Vaisanen K, Auvinen J (1980) "Effect of anticonvulsants on plasma haloperidol and thioridazine levels." Am J Psychiatry, 137, p. 819-21
- Sands CD, Robinson JD, Salem RB, Stewart RB, Muniz C (1987) "Effect of thioridazine on phenytoin serum concentration: a retrospective study." Drug Intell Clin Pharm, 21, p. 267-72
Drug and food interactions
phenytoin food
Applies to: Phenytoin Sodium, Extended Release (phenytoin)
ADJUST DOSING INTERVAL: Phenytoin bioavailability may decrease to subtherapeutic levels when the suspension is given concomitantly with enteral feedings. The mechanism may be related to phenytoin binding to substances in the enteral formula (e.g., calcium, protein) and/or binding to the tube lumen. Data have been conflicting and some studies have reported no changes in phenytoin levels, while others have reported significant reductions.
MONITOR: Acute consumption of alcohol may increase plasma phenytoin levels. Chronic consumption of alcohol may decrease plasma phenytoin levels. The mechanism of this interaction is related to induction of phenytoin metabolism by ethanol during chronic administration. Other hydantoin derivatives may be similarly affected by ethanol.
MANAGEMENT: Some experts have recommended interrupting the feeding for 2 hours before and after the phenytoin dose, giving the phenytoin suspension diluted in water, and flushing the tube with water after administration; however, this method may not entirely avoid the interaction and is not always clinically feasible. Patients should be closely monitored for clinical and laboratory evidence of altered phenytoin efficacy and levels upon initiation and discontinuation of enteral feedings. Dosage adjustments or intravenous administration may be required until therapeutic serum levels are obtained. In addition, patients receiving phenytoin therapy should be warned about the interaction between phenytoin and ethanol and they should be advised to notify their physician if they experience worsening of seizure control or symptoms of toxicity, including drowsiness, visual disturbances, change in mental status, nausea, or ataxia.
References
- Sandor P, Sellers EM, Dumbrell M, Khouw V (1981) "Effect of short- and long-term alcohol use on phenytoin kinetics in chronic alcoholics." Clin Pharmacol Ther, 30, p. 390-7
- Holtz L, Milton J, Sturek JK (1987) "Compatibility of medications with enteral feedings." JPEN J Parenter Enteral Nutr, 11, p. 183-6
- Sellers EM, Holloway MR (1978) "Drug kinetics and alcohol ingestion." Clin Pharmacokinet, 3, p. 440-52
- (2001) "Product Information. Dilantin (phenytoin)." Parke-Davis
- Doak KK, Haas CE, Dunnigan KJ, et al. (1998) "Bioavailability of phenytoin acid and phenytoin sodium with enteral feedings." Pharmacotherapy, 18, p. 637-45
- Rodman DP, Stevenson TL, Ray TR (1995) "Phenytoin malabsorption after jejunostomy tube delivery." Pharmacotherapy, 15, p. 801-5
- Au Yeung SC, Ensom MH (2000) "Phenytoin and enteral feedings: does evidence support an interaction?" Ann Pharmacother, 34, p. 896-905
- Ozuna J, Friel P (1984) "Effect of enteral tube feeding on serum phenytoin levels." J Neurosurg Nurs, 16, p. 289-91
- Faraji B, Yu PP (1998) "Serum phenytoin levels of patients on gastrostomy tube feeding." J Neurosci Nurs, 30, p. 55-9
- Marvel ME, Bertino JS (1991) "Comparative effects of an elemental and a complex enteral feeding formulation on the absorption of phenytoin suspension." JPEN J Parenter Enteral Nutr, 15, p. 316-8
- Fleisher D, Sheth N, Kou JH (1990) "Phenytoin interaction with enteral feedings administered through nasogastric tubes." JPEN J Parenter Enteral Nutr, 14, p. 513-6
- Haley CJ, Nelson J (1989) "Phenytoin-enteral feeding interaction." DICP, 23, p. 796-8
- Guidry JR, Eastwood TF, Curry SC (1989) "Phenytoin absorption in volunteers receiving selected enteral feedings." West J Med, 150, p. 659-61
- Krueger KA, Garnett WR, Comstock TJ, Fitzsimmons WE, Karnes HT, Pellock JM (1987) "Effect of two administration schedules of an enteral nutrient formula on phenytoin bioavailability." Epilepsia, 28, p. 706-12
- Cerner Multum, Inc. "UK Summary of Product Characteristics."
- Cerner Multum, Inc. "Australian Product Information."
promethazine food
Applies to: Antinaus 50 (promethazine)
GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.
MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.
References
- Lutz EG (1976) "Neuroleptic-induced akathisia and dystonia triggered by alcohol." JAMA, 236, p. 2422-3
- Freed E (1981) "Alcohol-triggered-neuroleptic-induced tremor, rigidity and dystonia." Med J Aust, 2, p. 44-5
Therapeutic duplication warnings
No duplication warnings were found for your selected drugs.
Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.
Drug Interaction Classification
Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. | |
No interaction information available. |
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