Skip to main content

Drug Interactions between D-G and metoprolol

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

Edit list (add/remove drugs)

Interactions between your drugs

Major

metoprolol dyphylline

Applies to: metoprolol and D-G (dyphylline / guaifenesin)

GENERALLY AVOID: The pharmacologic effects of theophyllines and beta-blockers are opposite. Nonselective and high doses of cardioselective beta-blockers may cause severe or fatal bronchospasm by opposing theophylline-induced bronchodilation. Ophthalmic beta-blockers undergo significant systemic absorption and may also interact. In addition, propranolol and other beta-blockers may reduce the CYP450 hepatic metabolism of theophylline, and serum theophylline levels may be increased.

MANAGEMENT: Oral and ophthalmic nonselective beta-blockers (e.g., carteolol, carvedilol, levobunolol, metipranolol, nadolol, oxprenolol, penbutolol, pindolol, propranolol, sotalol, and timolol) are considered contraindicated in patients with bronchospastic diseases. Cardioselective beta-blockers should generally be avoided, or used with extreme caution if no other alternatives are available and the benefits outweigh the risks of potentially severe bronchospasm. If patients do receive this combination, they should be closely monitored for increased serum theophylline levels but decreased bronchodilatory effectiveness.

References

  1. Upton RA "Pharmacokinetic interactions between theophylline and other medication (Part II)." Clin Pharmacokinet 20 (1991): 135-50
  2. Conrad KA, Nyman DW "Effects of metoprolol and propranolol on theophylline elimination." Clin Pharmacol Ther 28 (1980): 463-7
  3. Horvath JS, Woolcock AJ, Tiller DJ, Donnelly P, Armstrong J, Caterson R "A comparison of metoprolol and propranolol on blood pressure and respiratory function in patients with hypertension." Aust N Z J Med 8 (1978): 1-6
  4. Mue S, Sasaki T, Shibahara S, et al. "Influence of metoprolol on hemodynamics and respiratory function in asthmatic patients." Int J Clin Pharmacol Biopharm 17 (1979): 346-50
  5. Lombardi TP, Bertino JS, Goldberg A, Middleton E, Slaughter RL "The effects of a beta-2 selective adrenergic agonist and a beta- nonselective antagonist on theophylline clearance." J Clin Pharmacol 27 (1987): 523-9
View all 5 references

Switch to consumer interaction data

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

Switch to consumer interaction data

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

Switch to consumer interaction data

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

Loading...
QR code containing a link to this page

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.

Medical Disclaimer