Sucrose Acetate Isobutyrate (SAIB) as a Delivery Vehicle for Estradiol and Sulpiride: Evaluation of Endocrine Responses in Geldings and Ovarian Response in Seasonally Anovulatory Mares.
Authors: Oberhaus Erin L, Wilson Kaitlyn M, Camp Caroline M, Sones Jenny L
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Vegetable shortening has proven effective for sustained delivery of sulpiride in horses, but regulatory requirements demand a pharmaceutical-grade alternative; this research evaluated sucrose acetate isobutyrate (SAIB), a hydrophobic polymer vehicle, as a potential replacement across four experiments combining endocrine and ovarian outcome measures. Geldings receiving sulpiride in SAIB demonstrated prolactin elevation comparable to vegetable shortening delivery (P < .01), with pretreatment using estradiol benzoate (EB) rather than estradiol cypionate (ECP) producing significantly higher prolactin responses on days 5, 6 and 9; both estradiol formulations triggered equivalent luteinising hormone (LH) stimulation over 10 days. Staggered administration of EB and sulpiride (one day apart) extended prolactin elevation by two days compared to simultaneous injection, whilst maintaining equivalent LH responses, and when applied to seasonally anovulatory mares this non-simultaneous protocol showed a trend towards earlier ovarian response (P = .07). For practitioners managing reproductive cases—particularly attempting to synchronise cycling in mares during seasonal anoestrus—SAIB offers a regulatory-compliant alternative to vegetable shortening with demonstrated flexibility in dosing intervals; the apparent advantage of staggered EB-sulpiride administration in hastening ovarian response warrants consideration in breeding protocols, though further investigation into optimal spacing intervals and cost-benefit analysis would strengthen clinical recommendations.
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Practical Takeaways
- •SAIB is a viable pharmaceutical-grade alternative to vegetable shortening for sustained-release sulpiride delivery in horses, with similar efficacy and better regulatory compliance
- •Timing of estradiol and sulpiride administration can modulate endocrine responses; staggered dosing (one day apart) may extend prolactin elevation and accelerate ovarian activity in anovulatory mares
- •Estradiol benzoate and estradiol cypionate produce different prolactin responses when combined with sulpiride, which may influence protocol selection for reproductive management
Key Findings
- •SAIB delivered sulpiride with similar prolactin stimulation to vegetable shortening (P < 0.01), providing a pharmaceutical-grade alternative vehicle
- •Estradiol benzoate pretreatment produced higher prolactin responses to sulpiride on days 5, 6, and 9 compared to estradiol cypionate (P < 0.05)
- •Non-simultaneous EB-sulpiride injection (one day apart) extended prolactin response 2 days longer than simultaneous injection in geldings
- •Non-simultaneously treated seasonally anovulatory mares tended to show earlier ovarian response (P = 0.07) compared to simultaneous EB-sulpiride treatment