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Drug Interactions between Lufyllin-EPG and Primsol

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

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Interactions between your drugs

Moderate

trimethoprim PHENobarbital

Applies to: Primsol (trimethoprim) and Lufyllin-EPG (dyphylline / ephedrine / guaifenesin / phenobarbital)

MONITOR: Coadministration with potent inducers of CYP450 2C9 and 3A4 may decrease the plasma concentrations of sulfamethoxazole and trimethoprim. A small amount of sulfamethoxazole is metabolized by CYP450 2C9, while trimethoprim is partially metabolized by both CYP450 2C9 and 3A4. In a study of 10 HIV-infected patients receiving sulfamethoxazole-trimethoprim prophylaxis (800 mg-160 mg orally once a day) for at least one month, antituberculosis therapy containing rifampin (600 mg/day) given for more than 12 days decreased mean sulfamethoxazole systemic exposure (AUC) by 23% and mean trimethoprim AUC by 47%, most likely due to induction of hepatic microsomal enzymes by rifampin. The clinical significance of this interaction is unknown, but may be greater with low dosages of sulfamethoxazole-trimethoprim. A case-control study evaluating the effect of sulfamethoxazole-trimethoprim dosage on the risk of toxoplasmosis suggest that rifampin exposure may reduce the efficacy of sulfamethoxazole-trimethoprim prophylaxis. Other potent CYP450 inducers may interact similarly.

MANAGEMENT: The potential for diminished pharmacologic effects of sulfamethoxazole-trimethoprim should be considered during coadministration with potent CYP450 2C9 and 3A4 inducers, particularly when sulfamethoxazole-trimethoprim is used for prevention of toxoplasmic encephalitis in HIV patients because adequate drug levels are required in the central nervous system. It may be advisable to refrain from low-dose prophylactic regimens (less than 4 DS tablets per week). Alternative treatments may be required if an interaction is suspected.

References

  1. Bhatia RS, Uppal R, Malhi R, Behera D, Jindal SK "Drug interaction between rifampicin and cotrimazole in patients with tuberculosis." Hum Exp Toxicol 10 (1991): 419-21
  2. Ribera E, FernandezSola A, Juste C, Rovira A, Romero FJ, ArmadansGil L, Ruiz I, Ocana I, Pahissa A "Comparison of high and low doses of trimethoprim-sulfamethoxazole for primary prevention of toxoplasmic encephalitis in human immunodeficiency virus-infected patients." Clin Infect Dis 29 (1999): 1461-6
  3. Ribera E, Pou L, Fernandez-Sola A, et al. "Rifampin reduces concentrations of trimethoprim and sulfamethoxazole in serum in human immunodeficiency virus-infected patients." Antimicrob Agents Chemother 45 (2001): 3238-41

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Minor

ePHEDrine dyphylline

Applies to: Lufyllin-EPG (dyphylline / ephedrine / guaifenesin / phenobarbital) and Lufyllin-EPG (dyphylline / ephedrine / guaifenesin / phenobarbital)

Ephedrine-methylxanthine combinations are used for the treatment of asthma but the efficacy of the combination has been questioned. This combination may lead to increased xanthine side effects. The mechanism is unknown, but may be related to synergistic pharmacologic effects. Patients using this combination should be closely monitored for side effects such as nausea, vomiting, tachycardia, nervousness, or insomnia. If side effects are noted, the dosage of the xanthine may need to be decreased.

References

  1. Weinberger M, Bronsky E, Bensch GW, Bock GN, Yecies JJ "Interaction of ephedrine and theophylline." Clin Pharmacol Ther 17 (1975): 585-92
  2. Sims JA, doPico GA, Reed CE "Bronchodilating effect of oral theophylline-ephedrine combination." J Allergy Clin Immunol 62 (1978): 15-21
  3. Tinkelman DG, Avner SE "Ephedrine therapy in asthmatic children. Clinical tolerance and absence of side effects." JAMA 237 (1977): 553-7
  4. Weinberger MM, Brousky EA "Evaluation of oral bronchodilator therapy in asthmatic children: bronchodilators in asthmatic children." J Pediatr 84 (1974): 421-7
  5. Badiei B, Faciane J, Sly M "Effect of throphylline, ephedrine and theri combination upon exercise-induced airway obstruction." Ann Allergy 35 (1975): 32-6
View all 5 references

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Drug and food interactions

Major

PHENobarbital food

Applies to: Lufyllin-EPG (dyphylline / ephedrine / guaifenesin / phenobarbital)

GENERALLY AVOID: Concurrent acute use of barbiturates and ethanol may result in additive CNS effects, including impaired coordination, sedation, and death. Tolerance of these agents may occur with chronic use. The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

MANAGEMENT: The combination of ethanol and barbiturates should be avoided.

References

  1. Gupta RC, Kofoed J "Toxological statistics for barbiturates, other sedatives, and tranquilizers in Ontario: a 10-year survey." Can Med Assoc J 94 (1966): 863-5
  2. Misra PS, Lefevre A, Ishii H, Rubin E, Lieber CS "Increase of ethanol, meprobamate and pentobarbital metabolism after chronic ethanol administration in man and in rats." Am J Med 51 (1971): 346-51
  3. Saario I, Linnoila M "Effect of subacute treatment with hypnotics, alone or in combination with alcohol, on psychomotor skills related to driving." Acta Pharmacol Toxicol (Copenh) 38 (1976): 382-92
  4. Stead AH, Moffat AC "Quantification of the interaction between barbiturates and alcohol and interpretation of fatal blood concentrations." Hum Toxicol 2 (1983): 5-14
  5. Seixas FA "Drug/alcohol interactions: avert potential dangers." Geriatrics 34 (1979): 89-102
View all 5 references

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Moderate

ePHEDrine food

Applies to: Lufyllin-EPG (dyphylline / ephedrine / guaifenesin / phenobarbital)

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 "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res 1 (1979): 45-52
  2. Cavanaugh JH, Griffith JD, Oates JA "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther 11 (1970): 656
  3. "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc PROD (2001):
  4. "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals PROD (2001):
  5. "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals PROD (2001):
  6. "Product Information. Focalin (dexmethylphenidate)." Mikart Inc (2001):
  7. "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company (2002):
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.

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