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Drug Interactions between Magsal and phentermine / topiramate

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

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Interactions between your drugs

Major

phenyltoloxamine topiramate

Applies to: Magsal (magnesium salicylate / phenyltoloxamine) and phentermine / topiramate

MONITOR CLOSELY: Certain drugs such as carbonic anhydrase inhibitors and drugs with anticholinergic activity (e.g., antihistamines, antispasmodics, neuroleptics, phenothiazines, skeletal muscle relaxants, tricyclic antidepressants, disopyramide) may potentiate the risk of oligohidrosis and hyperthermia associated occasionally with the use of topiramate, particularly in pediatric patients. These agents may alter electrolyte and fluid balance (carbonic anhydrase inhibition), inhibit peripheral sweating mechanisms (anticholinergic effect), and/or interfere with core body temperature regulation in the hypothalamus (neuroleptics and phenothiazines), resulting in the inability to adjust to temperature changes, especially in hot weather. Also, agents with anticholinergic activity frequently cause drowsiness and other central nervous system-depressant effects, which may be additively or synergistically increased in patients also treated with topiramate.

MANAGEMENT: Caution is advised when topiramate is prescribed with other drugs that predispose patients to heat-related disorders, including carbonic anhydrase inhibitors and drugs with anticholinergic activity. Patients, particularly pediatric patients, should be monitored closely for evidence of decreased sweating and increased body temperature, especially in warm or hot weather. Proper hydration before and during vigorous activities or exposure to warm temperatures is recommended. Patients (or their guardians or caregivers) should contact their physician immediately if they are not sweating as usual, with or without a fever. Ambulatory patients treated with topiramate and agents with anticholinergic activity should also be made aware of the possibility of additive CNS effects (e.g., drowsiness, dizziness, lightheadedness, confusion) and counseled to avoid activities requiring mental alertness until they know how these agents affect them.

References

  1. "Product Information. Topamax (topiramate)." Ortho McNeil Pharmaceutical PROD (2001):

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Moderate

phentermine topiramate

Applies to: phentermine / topiramate and 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: 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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Moderate

phenyltoloxamine food

Applies to: Magsal (magnesium salicylate / phenyltoloxamine)

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

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Moderate

magnesium salicylate food

Applies to: Magsal (magnesium salicylate / phenyltoloxamine)

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

References

  1. "Product Information. Motrin (ibuprofen)." Pharmacia and Upjohn PROD (2002):

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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.

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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