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Last Updated: 2 years ago

Possible Interaction: Quinidine and Timolol

supplement:

Quinidine

drug:

Timolol

Research Papers that Mention the Interaction

Administration of quinidine with timolol eye drops to EMs resulted in a further significant reduction in heart rate (P = .02) and increase in plasma timolol concentration (P = .04).
CONCLUSIONS An individual's debrisoquin phenotype is an important determinant of beta-blockade following timolol eye drops, and metabolism of ti olol is inhibited and beta-blockade increased by coadministration of ora l quinidine.
OBJECTIVE To determine whether the effects of topically administered timolol in an individual would be dependent on … absence in that individual of the P-450 enzyme CYP2D6 and whether the effects of topically administered timolol would be increased and its … by the oral administration of quinidine , a known … CYP2D6.
JAMA  •  1995  |  View Paper
Quinidine administration increased timolol plasma levels and cardiac β‐blocking effects by 10% to 40%.
Timolol effects are augmented after quinidine administration.
Clinical pharmacology and therapeutics  •  1991  |  View Paper
In conclusion, the inhibition of timolol metabolism by quinidine should be taken into account when patients are treated with timolol.
The CYP2D6 inhibitor quinidine proved a potent competitive inhibitor of timolol metabolism, with an in vitro Ki value of 0.08 μM. Fluvoxamine, an inhibitor of CYP2C19, inhibited timolol metabolism to a lesser extent, confirming its minor contribution.
Drug Metabolism and Disposition  •  2007  |  View Paper