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Updated: Aug 14, 2026
10:02
Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Systemic bioavailability of ocularly applied 1% atropine eyedrops
T Kaila1, J M Korte, K M Saari
1Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland.
Acta Ophthalmologica Scandinavica
|May 13, 1999
Summary
Ophthalmic atropine eyedrops show considerable systemic bioavailability, with 1-hyoscyamine absorption explaining potential anticholinergic side effects. This study quantified atropine bioavailability in healthy volunteers.
Area of Science:
- Pharmacology
- Ophthalmology
- Clinical Pharmacology
Background:
- Atropine eyedrops are used clinically, but systemic anticholinergic side effects are sometimes reported.
- The pharmacokinetic basis for these systemic effects from ophthalmic atropine is not fully understood.
Purpose of the Study:
- To determine the systemic bioavailability of 1% atropine solution administered ocularly.
- To investigate the pharmacological basis for systemic effects of atropine eyedrops.
Main Methods:
- A randomized crossover study in six healthy volunteers.
- Administration of 0.3 mg atropine intravenously and ocularly.
- Plasma concentrations of 1-hyoscyamine measured using a muscarinic cholinoceptor binding assay.
Main Results:
- Mean bioavailability of 1-hyoscyamine after ocular administration was 63.5%.
- Significant interindividual variability was observed in absorption and elimination.
- Terminal half-life of 1-hyoscyamine was unaffected by the route of administration.
Conclusions:
- Systemic bioavailability of 1-hyoscyamine from atropine eyedrops is substantial.
- This finding supports the explanation for reported systemic anticholinergic side effects.
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