Drug Interactions between aspirin / diphenhydramine / phenylpropanolamine and Qsymia
This report displays the potential drug interactions for the following 2 drugs:
- aspirin/diphenhydramine/phenylpropanolamine
- Qsymia (phentermine/topiramate)
Interactions between your drugs
phenylpropanolamine phentermine
Applies to: aspirin / diphenhydramine / phenylpropanolamine and Qsymia (phentermine / topiramate)
CONTRAINDICATED: The efficacy of centrally-acting appetite suppressants in combination with other anorectic agents has not been studied, but available data suggest that combined use may have the potential for serious cardiac problems. In a case-control epidemiological study, the use of anorectic agents was associated with an increased risk of pulmonary hypertension, a rare but often fatal disorder, and use for longer than three months was associated with a 23-fold increase in risk. Increased risk of pulmonary hypertension with repeated courses of therapy cannot be excluded. The use of some anorectic agents such as fenfluramine and dexfenfluramine has been associated with valvular heart disease. Possible contributing factors include use for extended periods of time, higher than recommended dosages, and/or use in combination with other anorectic drugs.
MANAGEMENT: Centrally--acting appetite suppressants should not be used in combination with other anorectic agents, including prescription, over-the-counter, and herbal preparations. In addition, they are not recommended for patients who have used any anorectic agents within the prior year. The potential risk of possible serious adverse effects such as valvular heart disease and pulmonary hypertension should be assessed carefully against the benefit of weight loss, and baseline cardiac evaluation should be considered to detect preexisting valvular heart diseases or pulmonary hypertension prior to initiating treatment. These agents are not recommended for use in patients with known heart murmur or valvular heart disease, severe hypertension, or symptomatic cardiovascular disease including arrhythmias. Patients should be advised to immediately discontinue the medication and contact their physician if they experience potential signs and symptoms of pulmonary hypertension such as new onset or aggravation of exertional dyspnea, chest pain or tightness, syncope, and lower extremity edema.
References
- (2001) "Product Information. Meridia (sibutramine)." Knoll Pharmaceutical Company
- (2001) "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn
- (2012) "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals
- (2012) "Product Information. Diethylpropion Hydrochloride SR (diethylpropion)." Watson Pharmaceuticals
- (2012) "Product Information. Phendimetrazine Tartrate SR (phendimetrazine)." Sandoz Inc
diphenhydrAMINE topiramate
Applies to: aspirin / diphenhydramine / phenylpropanolamine and Qsymia (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
- (2001) "Product Information. Topamax (topiramate)." Ortho McNeil Pharmaceutical
phentermine topiramate
Applies to: 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
- (2001) "Product Information. Ionamin (phentermine)." Rhone Poulenc Rorer
Drug and food interactions
phenylpropanolamine food
Applies to: aspirin / diphenhydramine / phenylpropanolamine
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
- Mendelson J, Jones RT, Upton R, Jacob P 3rd (1995) "Methamphetamine and ethanol interactions in humans." Clin Pharmacol Ther, 57, p. 559-68
- (2001) "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn
- (2012) "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals
phentermine food
Applies to: 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
- Mendelson J, Jones RT, Upton R, Jacob P 3rd (1995) "Methamphetamine and ethanol interactions in humans." Clin Pharmacol Ther, 57, p. 559-68
- (2001) "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn
- (2012) "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals
aspirin food
Applies to: aspirin / diphenhydramine / phenylpropanolamine
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
- (2002) "Product Information. Motrin (ibuprofen)." Pharmacia and Upjohn
diphenhydrAMINE food
Applies to: aspirin / diphenhydramine / phenylpropanolamine
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
- 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
phenylpropanolamine food
Applies to: aspirin / diphenhydramine / phenylpropanolamine
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
- 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
- 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
- (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
- (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
- (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
- (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
- (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
aspirin food
Applies to: aspirin / diphenhydramine / phenylpropanolamine
One study has reported that coadministration of caffeine and aspirin lead to a 25% increase in the rate of appearance and 17% increase in maximum concentration of salicylate in the plasma. A significantly higher area under the plasma concentration time curve of salicylate was also reported when both drugs were administered together. The exact mechanism of this interaction has not been specified. Physicians and patients should be aware that coadministration of aspirin and caffeine may lead to higher salicylate levels faster.
References
- Yoovathaworn KC, Sriwatanakul K, Thithapandha A (1986) "Influence of caffeine on aspirin pharmacokinetics." Eur J Drug Metab Pharmacokinet, 11, p. 71-6
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
Report options
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| 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. | |
| No interaction information available. |
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