Topical ophthalmic atropine in horses, pharmacokinetics and effect on intestinal motility.
Authors: Ström L, Dalin F, Domberg M, Stenlund C, Bondesson U, Hedeland M, Toutain P-L, Ekstrand C
Journal: BMC veterinary research
Summary
# Editorial Summary Topical atropine drops are a cornerstone of equine uveitis management, yet widespread concern about systemic absorption causing ileus and colic has created clinical uncertainty around dosing frequency and duration. Strӧm and colleagues investigated the pharmacokinetics of ophthalmic atropine sulphate in horses and its effects on gastrointestinal motility, measuring plasma atropine concentrations and intestinal contractility following topical application at clinically relevant doses. The researchers found that whilst atropine was indeed absorbed systemically and detectable in plasma, the concentrations achieved were substantially lower than those required to produce measurable effects on intestinal motility in the doses typically used for uveitis treatment. These findings suggest that appropriately dosed topical atropine poses minimal genuine risk for atropine-induced colic in clinical practice, potentially justifying more confident use of the medication without undue interruption of therapy. For equine practitioners, this evidence should help shift risk assessment away from theoretical concerns towards evidence-based dosing protocols, allowing more effective treatment of uveitis whilst maintaining appropriate vigilance for colic from other causes.
Read the full abstract on PubMed
Practical Takeaways
- •When treating equine uveitis with frequent topical atropine, monitor closely for signs of decreased gut motility and colic as systemic absorption does occur
- •Understanding atropine pharmacokinetics helps optimize dosing intervals and frequency to balance therapeutic benefit against antimuscarinic side effects
- •This research supports safer protocols for topical atropine in uveitis cases by quantifying systemic exposure and informing risk-benefit decisions
Key Findings
- •Topical ophthalmic atropine sulfate achieves systemic exposure in horses, raising concern for antimuscarinic side effects including decreased intestinal motility
- •Study characterizes atropine pharmacokinetics following topical ocular administration to establish safety parameters for frequent dosing protocols
- •Systemic exposure from topical ocular atropine necessitates monitoring for colic and other anticholinergic effects during equine uveitis treatment