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Drug Interactions between Antrocol and telaprevir

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

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Interactions between your drugs

Major

PHENobarbital telaprevir

Applies to: Antrocol (atropine / phenobarbital) and telaprevir

CONTRAINDICATED: Coadministration with certain anticonvulsants may significantly decrease the plasma concentrations of telaprevir. The mechanism involves induction of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of telaprevir and other protease inhibitors. Anticonvulsants that are considered potent inducers of CYP450 3A4 include carbamazepine, phenobarbital, and phenytoin. In 11 study subjects, administration of telaprevir (750 mg every 8 hours for 10 days) with carbamazepine (200 mg every 12 hours for 17 days) decreased mean telaprevir peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) by 21%, 32% and 47%, respectively. When the same dosage regimen of telaprevir was coadministered with phenytoin (200 mg every 12 hours for 17 days) in 7 study subjects, mean telaprevir Cmax, AUC and Cmin reduced by 32%, 47% and 68%, respectively. In the presence of telaprevir, carbamazepine pharmacokinetics were not significantly altered, whereas phenytoin Cmax, AUC and Cmin increased by 27%, 31% and 36%, respectively. No data are available for phenobarbital.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic telaprevir levels, concomitant use with carbamazepine, phenobarbital, or phenytoin is considered contraindicated.

References

  1. (2011) "Product Information. Incivek (telaprevir)." Vertex Pharmaceuticals

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Drug and food interactions

Major

PHENobarbital food

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

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Moderate

telaprevir food

Applies to: telaprevir

ADJUST DOSING INTERVAL: Food significantly enhances the oral bioavailability of telaprevir. When given with a meal containing 533 kcal and 21 g fat, telaprevir systemic exposure (AUC) increased by 237% compared to administration under fasting conditions. The type of meal also affects the exposure to telaprevir. Relative to fasting, telaprevir AUC increased by approximately 117% with a low-fat meal (249 kcal; 3.6 g fat) and 330% with a high-fat meal (928 kcal; 56 g fat). In Phase 3 clinical trials, telaprevir doses were administered within 30 minutes of completing a meal or snack containing approximately 20 grams of fat.

MANAGEMENT: Telaprevir should be administered with food containing approximately 20 grams of fat. Patients should be advised that the fat content of the meal or snack is critical to the absorption of telaprevir. Food taken with telaprevir should be ingested within 30 minutes prior to each dose. Examples of some foods that could be taken with telaprevir include: bagel with cream cheese; half cup of nuts; 3 tablespoons of peanut butter; 1 cup of ice cream; 2 ounces of American or cheddar cheese; 2 ounces of potato chips; or half cup of trail mix.

References

  1. (2011) "Product Information. Incivek (telaprevir)." Vertex Pharmaceuticals

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Moderate

atropine food

Applies to: Antrocol (atropine / phenobarbital)

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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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.