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Drug Interactions between Istalol and Jay-Phyl

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

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Interactions between your drugs

Major

dyphylline timolol ophthalmic

Applies to: Jay-Phyl (dyphylline / guaifenesin) and Istalol (timolol ophthalmic)

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

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Drug and food interactions

No alcohol/food interactions were found. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.

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

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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