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Drug Interactions between Ismelin and metoprolol

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

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Interactions between your drugs

Moderate

guanethidine metoprolol

Applies to: Ismelin (guanethidine) and metoprolol

MONITOR: Sympathetic ganglion-blocking or catecholamine-depleting agents such as guanethidine, reserpine, and monoamine oxidase (MAO) inhibitors may potentiate the pharmacologic effects of beta-blockers, which are thought to competitively antagonize catecholamines at cardiac and other peripheral adrenergic neurons. Combining these medications may increase the risk of hypotension, orthostasis, bradycardia, and heart failure due to excessive reduction of sympathetic activity. A case report describes two elderly patients who developed bradycardia less than 2 weeks after the initiation of phenelzine during treatment with a beta-blocker (nadolol 40 mg/day or metoprolol 150 mg/day). The pulse rates returned to normal following a 50% reduction of the nadolol dosage and discontinuation of metoprolol. In another report, a young woman developed marked orthostatic hypotension following the addition of pindolol 2.5 mg three times a day to an existing regimen of tranylcypromine. The pindolol dosage was reduced to 2.5 mg twice a day until her blood pressure stabilized, then slowly increased to 5 mg three times a day.

MANAGEMENT: Caution is advised if beta-blockers, including ophthalmic formulations, are prescribed in combination with sympathetic ganglion-blocking or catecholamine-depleting agents. Patients should contact their doctor if they experience dizziness, lightheadedness, syncope, bradycardia, shortness of breath, difficulty breathing, edema, and/or chest pain.

References

  1. Reggev A, Vollhardt BR "Bradycardia induced by an interaction between phenelzine and beta blockers." Psychosomatics 30 (1989): 106-8
  2. Pettinger WA, Soyangco FG, Oates JA "Inhibition of monoamine oxidase in man by furazolidone." Clin Pharmacol Ther 9 (1968): 442-7
  3. Goldberg LI "Monoamine oxidase inhibitors: adverse reactions and possible mechanisms." JAMA 190 (1964): 456-62
  4. "Product Information. Hylorel (guanadrel)." Rhone Poulenc Rorer PROD (2001):
  5. "Product Information. Matulane (procarbazine)." Roche Laboratories PROD (2001):
  6. De Vita VT, Hahn MA, Oliverio VT "Monoamine oxidase inhibition by a new carcinostatic agent, n-isopropyl-a-(2-methylhydrazino)-p-toluamide (MIH). (30590)." Proc Soc Exp Biol Med 120 (1965): 561-5
  7. Kronig MH, Roose SP, Walsh BT, Woodring S, Glassman AH "Blood pressure effects of phenelzine." J Clin Psychopharmacol 3 (1983): 307-10
  8. Golwyn DH, Sevlie CP "Monoamine oxidase inhibitor hypertensive crisis headache and orthostatic hypotension." J Clin Psychopharmacol 13 (1993): 77-8
  9. "Product Information. Nardil (phenelzine)." Parke-Davis PROD (2001):
  10. "Product Information. Parnate (tranylcypromine)." SmithKline Beecham PROD (2001):
  11. "Product Information. Marplan (isocarboxazid)." Roche Laboratories PROD (2001):
  12. "Product Information. Toprol-XL (metoprolol)." Astra-Zeneca Pharmaceuticals PROD (2001):
  13. Kraus RP "Pindolol augmentation of tranylcypromine in psychotic depression." J Clin Psychopharmacol 17 (1997): 225-6
View all 13 references

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Drug and food interactions

Moderate

metoprolol food

Applies to: metoprolol

ADJUST DOSING INTERVAL: The bioavailability of metoprolol may be enhanced by food.

MANAGEMENT: Patients may be instructed to take metoprolol at the same time each day, preferably with or immediately following meals.

References

  1. "Product Information. Lopressor (metoprolol)." Novartis Pharmaceuticals PROD (2001):
  2. Darcy PF "Nutrient-drug interactions." Adverse Drug React Toxicol Rev 14 (1995): 233-54

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Moderate

guanethidine food

Applies to: Ismelin (guanethidine)

MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.

References

  1. Sternbach H "Fluoxetine-associated potentiation of calcium-channel blockers." J Clin Psychopharmacol 11 (1991): 390-1
  2. Shook TL, Kirshenbaum JM, Hundley RF, Shorey JM, Lamas GA "Ethanol intoxication complicating intravenous nitroglycerin therapy." Ann Intern Med 101 (1984): 498-9
  3. Feder R "Bradycardia and syncope induced by fluoxetine." J Clin Psychiatry 52 (1991): 139
  4. Ellison JM, Milofsky JE, Ely E "Fluoxetine-induced bradycardia and syncope in two patients." J Clin Psychiatry 51 (1990): 385-6
  5. Rodriguez de la Torre B, Dreher J, Malevany I, et al. "Serum levels and cardiovascular effects of tricyclic antidepressants and selective serotonin reuptake inhibitors in depressed patients." Ther Drug Monit 23 (2001): 435-40
  6. Cerner Multum, Inc. "Australian Product Information." O 0
  7. Pacher P, Kecskemeti V "Cardiovascular side effects of new antidepressants and antipsychotics: new drugs, old concerns?" Curr Pharm Des 10 (2004): 2463-75
  8. Andrews C, Pinner G "Postural hypotension induced by paroxetine." BMJ 316 (1998): 595
View all 8 references

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Moderate

metoprolol food

Applies to: metoprolol

ADJUST DOSING INTERVAL: Concurrent administration with calcium salts may decrease the oral bioavailability of atenolol and possibly other beta-blockers. The exact mechanism of interaction is unknown. In six healthy subjects, calcium 500 mg (as lactate, carbonate, and gluconate) reduced the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of atenolol (100 mg) by 51% and 32%, respectively. The elimination half-life increased by 44%. Twelve hours after the combination, beta-blocking activity (as indicated by inhibition of exercise tachycardia) was reduced compared to that with atenolol alone. However, during a 4-week treatment in six hypertensive patients, there was no difference in blood pressure values between treatments. The investigators suggest that prolongation of the elimination half-life induced by calcium coadministration may have led to atenolol cumulation during long-term dosing, which compensated for the reduced bioavailability.

MANAGEMENT: It may help to separate the administration times of beta-blockers and calcium products by at least 2 hours. Patients should be monitored for potentially diminished beta-blocking effects following the addition of calcium therapy.

References

  1. Kirch W, Schafer-Korting M, Axthelm T, Kohler H, Mutschler E "Interaction of atenolol with furosemide and calcium and aluminum salts." Clin Pharmacol Ther 30 (1981): 429-35

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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

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