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Drug Interactions between mephenytoin and Omnihist II LA

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

chlorpheniramine mephenytoin

Applies to: Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine) and mephenytoin

MONITOR: Toxic serum concentrations of phenytoin and involuntary movements have been reported during coadministration with chlorpheniramine. Symptoms resolved after chlorpheniramine was discontinued. The mechanism of this interaction is not known.

MANAGEMENT: Clinical monitoring of patient response, tolerance, and serum phenytoin concentrations is recommended. Patients should be advised to notify their physician if they experience symptoms of phenytoin toxicity (drowsiness, visual disturbances, change in mental status, nausea, or ataxia) or involuntary movements.

References

  1. Pugh RN, Geddes AM, Yeoman WB (1975) "Interaction of phenytoin with chlorpheniramine." Br J Clin Pharmacol, 2, p. 173-5
  2. Ahmad S, Laidlaw J, Houghton GW, Richens A (1975) "Involuntary movements caused by phenytoin intoxication in epileptic patients." J Neurol Neurosurg Psychiatry, 38, p. 225-31
  3. (2006) "Product Information. Tussionex PennKinetic (chlorpheniramine-hydrocodone)." UCB Pharma Inc
  4. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  5. (2017) "Product Information. TussiCaps (chlorpheniramine-hydrocodone)." ECR Pharmaceuticals
View all 5 references

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Moderate

chlorpheniramine methscopolamine

Applies to: Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine) and Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine)

MONITOR: Agents with anticholinergic properties (e.g., sedating antihistamines; antispasmodics; neuroleptics; phenothiazines; skeletal muscle relaxants; tricyclic antidepressants; disopyramide) may have additive effects when used in combination. Excessive parasympatholytic effects may result in paralytic ileus, hyperthermia, heat stroke, and the anticholinergic intoxication syndrome. Peripheral symptoms of intoxication commonly include mydriasis, blurred vision, flushed face, fever, dry skin and mucous membranes, tachycardia, urinary retention, and constipation. Central symptoms may include memory loss, disorientation, incoherence, hallucinations, psychosis, delirium, hyperactivity, twitching or jerking movements, stereotypy, and seizures. Central nervous system-depressant effects may also be additively or synergistically increased when these agents are combined, especially in elderly or debilitated patients. Use of neuroleptics in combination with other neuroleptics or anticholinergic agents may increase the risk of tardive dyskinesia. In addition, some neuroleptics and tricyclic antidepressants may cause prolongation of the QT interval and theoretically, concurrent use of two or more drugs that can cause QT interval prolongation may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death.

MANAGEMENT: Caution is advised when agents with anticholinergic properties are combined, particularly in the elderly and those with underlying organic brain disease, who tend to be more sensitive to the central anticholinergic effects of these drugs and in whom toxicity symptoms may be easily overlooked. Patients should be advised to notify their physician promptly if they experience potential symptoms of anticholinergic intoxication such as abdominal pain, fever, heat intolerance, blurred vision, confusion, and/or hallucinations. Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them. A reduction in anticholinergic dosages may be necessary if excessive adverse effects develop.

References

  1. Stadnyk AN, Glezos JD (1983) "Drug-induced heat stroke." Can Med Assoc J, 128, p. 957-9
  2. Zelman S, Guillan R (1970) "Heat stroke in phenothiazine-treated patients: a report of three fatalities." Am J Psychiatry, 126, p. 1787-90
  3. Mann SC, Boger WP (1978) "Psychotropic drugs, summer heat and humidity, and hyperplexia: a danger restated." Am J Psychiatry, 135, p. 1097-100
  4. Warnes H, Lehmann HE, Ban TA (1967) "Adynamic ileus during psychoactive medication: a report of three fatal and five severe cases." Can Med Assoc J, 96, p. 1112-3
  5. Gershon S, Neubauer H, Sundland DM (1965) "Interaction between some anticholinergic agents and phenothiazines." Clin Pharmacol Ther, 6, p. 749-56
  6. Sarnquist F, Larson CP Jr (1973) "Drug-induced heat stroke." Anesthesiology, 39, p. 348-50
  7. Johnson AL, Hollister LE, Berger PA (1981) "The anticholinergic intoxication syndrome: diagnosis and treatment." J Clin Psychiatry, 42, p. 313-7
  8. Lee BS (1986) "Possibility of hyperpyrexia with antipsychotic and anticholinergic drugs." J Clin Psychiatry, 47, p. 571
  9. Forester D (1978) "Fatal drug-induced heat stroke." JACEP, 7, p. 243-4
  10. Moreau A, Jones BD, Banno V (1986) "Chronic central anticholinergic toxicity in manic depressive illness mimicking dementia." Can J Psychiatry, 31, p. 339-41
  11. Hvizdos AJ, Bennett JA, Wells BG, Rappaport KB, Mendel SA (1983) "Anticholinergic psychosis in a patient receiving usual doses of haloperidol." Clin Pharm, 2, p. 174-8
  12. Cohen MA, Alfonso CA, Mosquera M (1994) "Development of urinary retention during treatment with clozapine and meclizine [published erratum appears in Am J Psychiatry 1994 Jun;151(6):952]." Am J Psychiatry, 151, p. 619-20
  13. (2001) "Product Information. Cogentin (benztropine)." Merck & Co., Inc
  14. Kulik AV, Wilbur R (1982) "Delirium and stereotypy from anticholinergic antiparkinson drugs." Prog Neuropsychopharmacol Biol Psychiatry, 6, p. 75-82
  15. (2001) "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories
View all 15 references

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Moderate

phenylephrine methscopolamine

Applies to: Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine) and Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine)

MONITOR: The pressor response to phenylephrine may be potentiated by the vagolytic effect of atropine, which inhibits the reflex bradycardia that would normally accompany any increases in blood pressure induced by phenylephrine. Other antimuscarinic agents may also participate in this interaction, although clinical data are lacking. In one report, pseudo-pheochromocytoma (i.e., significant increases in blood pressure and tachycardia) occurred in seven patients who underwent eye surgery and were given phenylephrine 10% ophthalmic solution and systemic atropine, three of whom subsequently developed left ventricular failure and pulmonary edema that required intensive care monitoring. Two patients had preexisting hypertension, while others had no known history of cardiovascular disease. All had received general anesthesia with propofol, phenoperidine, and vecuronium. Since phenylephrine use alone may be associated with cardiovascular toxicities including hypertension, arrhythmia, myocardial infarction and cardiac failure, the extent of involvement by atropine is uncertain. The authors reported no further cardiovascular events following implementation of various measures that reduced phenylephrine dosage and systemic exposure, including: use of a milder strength of phenylephrine ophthalmic solution; swabbing to minimize drainage into the nasolachrymal duct to the nasal mucosa; and use of a cannula to reduce drop size. In a study of six healthy volunteers, diastolic and systolic blood pressure increased by 4 mmHg following administration of phenylephrine (0.42 mcg/kg/min), compared to 17 mmHg when phenylephrine was given after three doses of atropine (0.02, 0.01 and 0.01 mg/kg at 30 minute intervals).

MANAGEMENT: Caution is advised if phenylephrine (systemic or ophthalmic) is used in combination with atropine or other antimuscarinic agents. Cardiovascular status, including blood pressure and heart rate, should be closely monitored. When using ophthalmic formulations, measures to minimize systemic absorption should be employed, such as digital compression of the lacrimal sac or lid closure after instillation. A milder strength (< 10%) is preferable if phenylephrine ophthalmic solution is given.

References

  1. Daelman F, Andrejak M, Rajaonarivony D, Bryselbout E, Jezraoui P, Ossart M (1994) "Phenylephrine eyedrops, systemic atropine and cardiovascular adverse events." Therapie, 49, p. 467
  2. Fraunfelder FT, Fraunfelder FW; Randall JA (2001) "Drug-Induced Ocular Side Effects" Boston, MA: Butterworth-Heinemann
  3. Lai YK (1989) "Adverse effect of intraoperative phenylephrine 10%: case report." Br J Ophthalmol, 73, p. 468-9
  4. Van Der Spek AF, Hantler CB (1986) "Phenylephrine eyedrops and anesthesia." Anesthesiology, 64, p. 812-4
  5. Levine MA, Leenen FH (1992) "Role of vagal activity in the cardiovascular responses to phenylephrine in man." Br J Clin Pharmacol, 33, p. 333-6
View all 5 references

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Drug and food interactions

Moderate

chlorpheniramine food

Applies to: Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine)

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References

  1. Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
  2. Gilman AG, eds., Nies AS, Rall TW, Taylor P (1990) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc.
  3. (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
  4. (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka American Pharmaceuticals Inc
View all 4 references

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Moderate

mephenytoin food

Applies to: mephenytoin

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

  1. 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
  2. Holtz L, Milton J, Sturek JK (1987) "Compatibility of medications with enteral feedings." JPEN J Parenter Enteral Nutr, 11, p. 183-6
  3. Sellers EM, Holloway MR (1978) "Drug kinetics and alcohol ingestion." Clin Pharmacokinet, 3, p. 440-52
  4. (2001) "Product Information. Dilantin (phenytoin)." Parke-Davis
  5. Doak KK, Haas CE, Dunnigan KJ, et al. (1998) "Bioavailability of phenytoin acid and phenytoin sodium with enteral feedings." Pharmacotherapy, 18, p. 637-45
  6. Rodman DP, Stevenson TL, Ray TR (1995) "Phenytoin malabsorption after jejunostomy tube delivery." Pharmacotherapy, 15, p. 801-5
  7. Au Yeung SC, Ensom MH (2000) "Phenytoin and enteral feedings: does evidence support an interaction?" Ann Pharmacother, 34, p. 896-905
  8. Ozuna J, Friel P (1984) "Effect of enteral tube feeding on serum phenytoin levels." J Neurosurg Nurs, 16, p. 289-91
  9. Faraji B, Yu PP (1998) "Serum phenytoin levels of patients on gastrostomy tube feeding." J Neurosci Nurs, 30, p. 55-9
  10. 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
  11. 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
  12. Haley CJ, Nelson J (1989) "Phenytoin-enteral feeding interaction." DICP, 23, p. 796-8
  13. Guidry JR, Eastwood TF, Curry SC (1989) "Phenytoin absorption in volunteers receiving selected enteral feedings." West J Med, 150, p. 659-61
  14. 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
  15. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  16. Cerner Multum, Inc. "Australian Product Information."
View all 16 references

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Moderate

methscopolamine food

Applies to: Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine)

GENERALLY AVOID: Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.

MANAGEMENT: Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.

References

  1. Linnoila M (1973) "Drug effects on psychomotor skills related to driving: interaction of atropine, glycopyrrhonium and alcohol." Eur J Clin Pharmacol, 6, p. 107-12

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Moderate

phenylephrine food

Applies to: Omnihist II LA (chlorpheniramine / methscopolamine / phenylephrine)

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

  1. 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
  2. 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
  3. (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
  4. (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
  5. (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
  6. (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
  7. (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
View all 7 references

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Therapeutic duplication warnings

No 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

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor 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.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.