Pharmacokinetics and ex vivo anti-inflammatory effects of oral misoprostol in horses.
Authors: Martin E M, Schirmer J M, Jones S L, Davis J L
Journal: Equine veterinary journal
Summary
# Oral Misoprostol in Horses: Pharmacokinetics and Anti-inflammatory Potential Despite widespread anecdotal use in equine practice for NSAID-induced gastric injury prevention, the pharmacological behaviour of misoprostol in horses remained poorly characterised. Martin and colleagues investigated both the absorption profile of a single 5 μg/kg oral dose and its capacity to suppress inflammatory cytokine production, using six healthy horses and measuring misoprostol free acid concentrations via advanced mass spectrometry alongside ex vivo leucocyte responses to lipopolysaccharide stimulation. The drug demonstrated rapid oral bioavailability with peak plasma concentration achieved within 23.4 minutes and an AUC of 0.4 h·ng/mL, yet disappointingly produced no significant reduction in tumour necrosis factor-alpha messenger RNA expression in stimulated equine leucocytes at any timepoint, including at peak drug concentration. These findings suggest that whilst misoprostol reaches systemic circulation efficiently in horses, a single dose at this concentration may be insufficient to elicit measurable anti-inflammatory effects through TNF-α suppression, highlighting the need for investigation of cumulative dosing protocols and synergistic combinations with other gastroprotective or anti-inflammatory agents before definitive clinical recommendations can be made.
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Practical Takeaways
- •Anecdotal use of misoprostol for NSAID-induced GI injury in horses lacks ex vivo evidence of anti-inflammatory efficacy at standard 5 μg/kg dosing
- •Alternative dosing strategies, repeated dosing, or combination therapy with other anti-inflammatory agents may warrant investigation before clinical recommendations can be made
- •Current evidence does not support misoprostol as an effective standalone anti-inflammatory agent for equine practice based on this preliminary study
Key Findings
- •Oral misoprostol 5 μg/kg produced rapid absorption with Tmax of 23.4 ± 2.4 minutes, Cmax of 0.29 ± 0.07 ng/mL, and AUC of 0.4 ± 0.12 h ng/mL
- •LPS stimulation significantly increased TNF-α mRNA in equine leucocytes ex vivo, but misoprostol had no significant inhibitory effect even at peak plasma concentration
- •Single-dose oral misoprostol administration showed no meaningful anti-inflammatory effect on TNF-α production in this ex vivo model