Drug Interaction Report
2 potential interactions and/or warnings found for the following 2 drugs:
- fosphenytoin
- Truphylline (aminophylline)
Interactions between your drugs
aminophylline fosphenytoin
Applies to: Truphylline (aminophylline), fosphenytoin
MONITOR: Phenytoin has been reported to increase the clearance of theophylline by 40% to 50%, presumably by enhancing the hepatic CYP450 metabolism of theophylline. Also, coadministration of theophylline has been reported to lower serum phenytoin concentrations. Other hydantoins and hepatically metabolized methylxanthines may also interact.
MANAGEMENT: Management consists of monitoring clinical response and serum concentrations of both drugs and adjusting dosages as necessary. Patients should be advised to report loss of seizure control or worsening of respiratory symptoms to their physician.
References (4)
- Upton RA (1991) "Pharmacokinetic interactions between theophylline and other medication (Part I)." Clin Pharmacokinet, 20, p. 66-80
- Miller M, Cosgriff J, Kwong T, Morken DA (1984) "Influence of phenytoin on theophylline clearance." Clin Pharmacol Ther, 35, p. 666-9
- Crowley JJ, Cusack BJ, Jue SG, et al. (1987) "Cigarette smoking and theophylline metabolism: effects of phenytoin." Clin Pharmacol Ther, 42, p. 334-40
- Sklar SJ, Wagner (1985) "Enhanced theophylline clearance secondary to phenytoin therapy." Drug Intell Clin Pharm, 19, p. 34-6
Drug and food interactions
aminophylline food
Applies to: Truphylline (aminophylline)
MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.
MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.
References (7)
- Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
- Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
- (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
- (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
- (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
- (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
- (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
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.
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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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