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Drug Interactions between Lomaira and Qsymia

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

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Interactions between your drugs

Moderate

phentermine topiramate

Applies to: Lomaira (phentermine) and Qsymia (phentermine / topiramate) and Qsymia (phentermine / topiramate)

MONITOR: Coadministration with topiramate may increase the plasma concentrations of phentermine. The exact mechanism of interaction has not been established. When a single 15 mg dose of phentermine was administered with a 92 mg dose of topiramate, phentermine peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 13% and 42%, respectively, compared to phentermine administered alone. No significant changes were observed in the pharmacokinetics of topiramate.

MANAGEMENT: Caution is advised when phentermine is used in combination with topiramate. Patients should be monitored for potentially increased adverse effects of phentermine such as dizziness, restlessness, insomnia, tremor, headache, euphoria, dysphoria, palpitation, tachycardia, and blood pressure elevation.

References

  1. "Product Information. Ionamin (phentermine)." Rhone Poulenc Rorer PROD (2001):

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Drug and food interactions

Moderate

phentermine food

Applies to: Lomaira (phentermine) and Qsymia (phentermine / topiramate)

GENERALLY AVOID: Alcohol may potentiate the central nervous system and cardiovascular effects of centrally-acting appetite suppressants. In one study, concurrent administration of methamphetamine (30 mg intravenously) and ethanol (1 gm/kg orally over 30 minutes) increased heart rate by 24 beats/minute compared to methamphetamine alone. This increases cardiac work and myocardial oxygen consumption, which may lead to more adverse cardiovascular effects than either agent alone. Subjective effects of ethanol were diminished in the eight study subjects, but those of methamphetamine were not affected. The pharmacokinetics of methamphetamine were also unaffected except for a decrease in the apparent volume of distribution at steady state.

MANAGEMENT: Concomitant use of centrally-acting appetite suppressants and alcohol should be avoided if possible, especially in patients with a history of cardiovascular disease. Patients should be counselled 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. Mendelson J, Jones RT, Upton R, Jacob P 3rd "Methamphetamine and ethanol interactions in humans." Clin Pharmacol Ther 57 (1995): 559-68
  2. "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn PROD (2001):
  3. "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals (2012):

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Stimulants

Therapeutic duplication

The recommended maximum number of medicines in the 'stimulants' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'stimulants' category:

  • Lomaira (phentermine)
  • Qsymia (phentermine/topiramate)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

Duplication

Anorexiants

Therapeutic duplication

The recommended maximum number of medicines in the 'anorexiants' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'anorexiants' category:

  • Lomaira (phentermine)
  • Qsymia (phentermine/topiramate)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

Duplication

Cerebral stimulants

Therapeutic duplication

The recommended maximum number of medicines in the 'cerebral stimulants' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'cerebral stimulants' category:

  • Lomaira (phentermine)
  • Qsymia (phentermine/topiramate)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

See also

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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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