Abstract • A randomized, double-masked study of the effect of terbutaline sulfate, a selective β2-agonist, on the rate of aqueous humor formation was performed in awake and sleeping normal human subjects. The rate of aqueous formation was measured by fluorophotometry. Both the drug- and placebo-treated eyes showed a statistically significant nocturnal reduction of the flow rate (36% suppression in the terbutaline-treated eyes and 43% suppression in the placebo-treated eyes). Terbutaline had no effect on daytime aqueous flow rates, but stimulated flow by 15% during sleep. The drug had no significant effect on intraocular pressure. This study confirms past observations that β-agonists exert their maximal effects during sleep, when endogenous adrenergic stimulation is at a minimum. References 1. Ericson LA: Twenty-four hourly variations in the inflow of aqueous humor . Acta Ophthalmol 1958;36:381-385.Crossref 2. Reiss GR, Lee DA, Topper JE, et al: Aqueous humor flow during sleep . Invest Ophthalmol Vis Sci 1983;25:776-778. 3. Topper JE, Brubaker RF: Effects of timolol, epinephrine, and acetazolamide on aqueous flow during sleep . Invest Ophthalmol Vis Sci 1985;26:1315-1319. 4. Brubaker RF, Carlson KH, Kullerstrand LJ, et al: Topical forskolin (colforsin) and aqueous flow in humans . Arch Ophthalmol 1987;105:637-641.Crossref 5. Larson RS, Brubaker RF: Isoproterenol stimulates aqueous flow in humans with Horner's syndrome . Invest Ophthalmol Vis Sci 1988;29:621-625. 6. Bausher LP, Gregory DS, Sears ML: Interaction between alpha2- and beta2-adrenergic receptors in rabbit ciliary processes . Curr Eye Res 1987;6:497-505.Crossref 7. Mittag TW, Tormay A: Adrenergic receptor subtypes in rabbit iris-ciliary body membranes: Classification by radioligand studies . Exp Eye Res 1985;40:239-249.Crossref 8. Nathanson JA: Adrenergic regulation of intraocular pressure: Identification of β2-adrenergic-stimulated adenylate cyclase in ciliary process epithelium . Proc Natl Acad Sci USA 1980;17:7420-7424.Crossref 9. McLaren JW, Brubaker RF: A two-dimensional scanning ocular fluorophotometer . Invest Ophthalmol Vis Sci 1985;26:144-152. 10. Robertson D, Garland JA, Robertson RM, et al: Comparative assessment of stimuli that release neuronal and adrenomedullary catecholamines in man . Circulation 1979;59:637-643.Crossref 11. Saar N, Gordon RD: Variability of plasma catecholamine levels: Age, duration of posture and time of day . Br J Clin Pharmacol 1979;8:353-358.Crossref 12. Neufeld A: Epinephrine and timolol: How do these drugs lower intraocular pressure? Ann Ophthalmol 1981;13:1109-1111. 13. Bartels SP, Roth HO, Jumblatt MM, et al: Pharmacologic effects of topical timolol in the rabbit eye . Invest Ophthalmol Vis Sci 1980;19:1189-1197.
Archives of Ophthalmology – American Medical Association
Published: Sep 1, 1988