Comparison of dorzolamide and timolol as suppressors of aqueous humor flow in humans

Arch Ophthalmol. 1997 Nov;115(11):1368-71. doi: 10.1001/archopht.1997.01100160538002.

Abstract

Objectives: To measure the effectiveness of topical 2% dorzolamide hydrochloride (Trusopt, Merck & Co Inc, Whitehouse Station, NJ) as a suppressor of aqueous humor flow in the human eye as compared with the effectiveness of 0.5% timolol maleate (Timoptic, Merck & Co Inc) and to measure the additivity of the 2 drugs.

Design: A randomized, double-masked, placebo-controlled study of 40 human subjects was carried out in 2 academic centers (Mayo Clinic, Rochester, Minn, and University of Uppsala, Uppsala, Sweden). The rate of aqueous flow was measured from 8 AM to 4 PM by means of fluorophotometry after administration of doses of each drug singly and both drugs together.

Results: Dorzolamide reduced aqueous flow from 3.07 +/- 0.63 microL/min (mean +/- SD) to 2.53 +/- 0.60 microL/min, a reduction of 18% (P < .001). Timolol reduced aqueous flow from the same beginning rate to 1.64 +/- 0.35 microL/min, a reduction of 47% (P < .001). The inhibitory effect of timolol was 2.6 times the inhibitory effect of dorzolamide (P < .001). The 2 drugs were almost completely additive, and together reduced the flow to 1.37 +/- 0.33 microL/min, a reduction of 55%. Consistent effects were observed on intraocular pressure.

Conclusions: Timolol is more effective than dorzolamide as a suppressor of aqueous humor flow in the normal human eye. Timolol and dorzolamide are additive in their effects, both on aqueous flow and intraocular pressure.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adrenergic beta-Antagonists / administration & dosage*
  • Adult
  • Aqueous Humor / drug effects*
  • Aqueous Humor / metabolism
  • Carbonic Anhydrase Inhibitors / administration & dosage*
  • Double-Blind Method
  • Drug Combinations
  • Drug Synergism
  • Female
  • Fluorophotometry
  • Humans
  • Intraocular Pressure / drug effects
  • Male
  • Middle Aged
  • Ophthalmic Solutions
  • Sulfonamides / administration & dosage*
  • Thiophenes / administration & dosage*
  • Timolol / administration & dosage*

Substances

  • Adrenergic beta-Antagonists
  • Carbonic Anhydrase Inhibitors
  • Drug Combinations
  • Ophthalmic Solutions
  • Sulfonamides
  • Thiophenes
  • Timolol
  • dorzolamide