Pharmacokinetics of Intrarectal Altrenogest in Horses

Council‐Troche, R. McAlister; Dollen, Karen A. Von; Beachler, Theresa; Bailey, C. Scott; Davis, Jennifer L.; Lyle, Sara K.

doi:10.1016/j.jevs.2018.10.001

Cited by 6 publications

(5 citation statements)

References 19 publications

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“…7‐14 days) formulations are also available that may be administered intramuscularly on a weekly to biweekly basis, providing an avenue of administration in mares who are unable to receive oral medications whether due to administrator preference, mare cooperation or concurrent maternal disease (McKinnon et al., 2000; Vanderwall et al., 2007). A recent study also examined the pharmacokinetics of rectally administered altrenogest and found that due to rectal bioavailability, administration of 0.088 mg/kg bwt every 4–8 h would be required to reach acceptable therapeutic levels (Ellis et al., 2019).…”

Section: Progestinsmentioning

confidence: 99%

Ancillary treatment to support pregnancy in cases of medical disease

Beachler

2022

Equine Veterinary Education

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Section: Progestinsmentioning

confidence: 99%

Ancillary treatment to support pregnancy in cases of medical disease

Beachler

2022

Equine Veterinary Education

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“…Therefore, the pharmacokinetics of intra-rectal altrenogest has also been assessed. Ellis et al (2019) administered 0.088 mg/kg of altrenogest both per rectum and per oral for 5 days, and altrenogest was detected in circulation as quickly as 15 min following administration. The C max of rectal altrenogest was considerably lower than that of oral (2.54 vs. 16.00 respectively), and clearance of altrenogest was more rapid in the rectal administration group.…”

Section: Pharmacokinetics Of Altrenogestmentioning

confidence: 99%

The use of progestins in equine medicine: A review

Fedorka

Troedsson

2020

Equine Veterinary Education

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Progesterone is in constant fluctuation throughout the lifespan of the horse. As a key regulator of the hypothalamicpituitary-gonadal axis, progesterone is involved in numerous aspects of reproduction. Synthetic analogs of progesterone, deemed progestins, are widely available to industry to act as progestogenic within the reproductive tract, although few are bioactive in the horse. Utilised to suppress oestrous, delay ovulation, maintain pregnancy, and for behavioural modifications, progestins are a commonly administered class of pharmaceuticals in veterinary medicine. In this review, we discuss the progestins available to equine industry, in addition to assessing efficacy, pharmacokinetics, and potential side effects following administration of each.

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“…5 Doubling oral dose (0.088 mg/kg) was recommended for intrarectal treatment to mares unable or unwilling to receive oral treatment. 9 This treatment resulted in plasma concentrations > 0.5 ng/ml that were maintained for 5.5 hours (range, 3 -8 hours). Although intrarectal treatment is potentially useful for mares that cannot receive oral treatment, increased handling of this hormone, every 4 -8 hours, poses a greater health risks to personnel.…”

Section: Introductionmentioning

confidence: 96%

Comparison of two altrenogest preparations in mares: a pilot study

Loy¹,

Norman²,

Ip³

et al. 2020

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Altrenogest is a synthetic progestin used in reproductive management of horses. Aims were to characterize and compare plasma altrenogest concentrations associated with weekly injectable versus daily oral preparations of altrenogest treatments. We hypothesized that an injectable preparation would not maintain concentrations higher than an oral preparation given once weekly. Two mares with no in vivo source of progesterone received either Treatment A (150 mg intramuscular altrenogest on days 0, 7, and 14) or Treatment B (0.044 mg/kg bodyweight of oral altrenogest daily for 3 weeks). After a 3-week washout period, mares received the opposite treatment for 3 weeks. Blood was collected prior to treatments and on days 0, 1, 4, 7, 8, 11, 14, 15, 18, and 21. High-performance liquid chromatography-tandem mass spectrometry was used for altrenogest assays. Mean minimum plasma concentrations after Treatments A and B were 1.51 ± 0.65 and 2.38 ± 1.53 ng/ml, respectively. Plasma altrenogest concentrations were significantly higher in Treatment A than Treatment B at 24 hours posttreatment (days 1, 8, and 15). No significant difference between plasma altrenogest concentrations was detected on days 4 and 7 of each week. Finding that plasma altrenogest concentrations were higher for Treatment A at all time points except days 7, 14, and 21 supported our hypothesis. An injectable altrenogest preparation may be considered a more practical and safer solution for long-term treatment; based on this study, it was comparable to a proven daily oral altrenogest treatment for a minimum of 4 days.

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Pharmacokinetics of Intrarectal Altrenogest in Horses

Cited by 6 publications

References 19 publications

Ancillary treatment to support pregnancy in cases of medical disease

Ancillary treatment to support pregnancy in cases of medical disease

The use of progestins in equine medicine: A review

Comparison of two altrenogest preparations in mares: a pilot study

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