Journal of veterinary pharmacology and therapeutics1990; 13(4); 393-403; doi: 10.1111/j.1365-2885.1990.tb00794.x

Bioavailability of ascorbic acid in horses.

Abstract: The bioavailability of ascorbic acid administered to thoroughbreds by intramuscular injection was investigated. For intramuscular injection two preparations were studied, and the percentage bioavailability up to 24 h of 10 g of ascorbic acid was 95% +/- 22 in four horses and 60% in two horses with preparations A and B, respectively. Bioavailability at 24 h in three horses injected subcutaneously with 10 g of preparation B was 82%. Intramuscular injection of both preparations was apparently well tolerated while subcutaneous injection of preparation B (pH 6.0) was associated with marked irritancy. In a cross-over trial in seven thoroughbreds the effect of 13 or 15 days of oral administration of crystalline ascorbic acid (20 g) or ascorbyl palmitate (47 g) on plasma ascorbic-acid concentrations was investigated. Marked differences occurred between individuals. There was a greater increase in plasma ascorbic-acid concentration with ascorbyl palmitate compared to ascorbic acid at 6 and 24 h following administration. In two horses there was no increase in plasma ascorbic acid at 6 h following either oral preparation. The finding of lowered plasma ascorbic-acid concentrations following a period of supplementation warrants further investigation to assess its significance.
Publication Date: 1990-12-01 PubMed ID: 2287031DOI: 10.1111/j.1365-2885.1990.tb00794.xGoogle Scholar: Lookup
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The research studied the efficacy and safety of administering ascorbic acid (vitamin C) in horses via two methods: intramuscular injection and oral intake. Comparing two preparations, the study found that the bioavailability of ascorbic acid was higher when injected. However, the oral intake method produced variable results among the horses.

Methods and materials

  • The research involved thoroughbred horses who were administered with ascorbic acid – either through intramuscular injection or oral intake.
  • For intramuscular injection, two separate formulations (referred to as preparations A and B) were studied. In the case of oral intake, the ascorbic acid was administered either as pure ascorbic acid or as an ascorbyl palmitate preparation.

Results studies on bioavailability through injections

  • The researchers measured the bioavailability (how effectively the body can utilize the administered nutrient) of ascorbic acid up to 24 hours after administration and found that with preparation A, it was 95% (with some margin of error) in four horses.
  • With preparation B, the bioavailability dropped to 60% in two other horses.
  • When the ascorbic acid (using preparation B) was injected subcutaneously (just under the skin, rather than into the muscle), the bioavailability was slightly higher at 82% in three horses.
  • However, the researchers did note that the subcutaneous injection of preparation B was associated with notable skin irritation.

Results studies on bioavailability through oral intake

  • The researchers conducted a cross-over trial involving seven thoroughbreds, where they compared the effects of administering 20 grams of crystalline ascorbic acid or 47 grams of ascorbyl palmitate over 13-15 days.
  • They found that the increase in plasma ascorbic-acid concentration was higher with the ascorbyl palmitate compared to the pure ascorbic acid at both 6 and 24 hours after administration.
  • However, the researchers also noticed that there was a wide variance between individual horses. In two horses, there was no significant increase in plasma ascorbic acid even after 6 hours of administration.
  • The researchers also noticed that ascorbic-acid levels in the blood decreased after a period of supplementation, indicating that this requires further study.

Cite This Article

Snow DH, Frigg M. (1990). Bioavailability of ascorbic acid in horses. J Vet Pharmacol Ther, 13(4), 393-403.


ISSN: 0140-7783
NlmUniqueID: 7910920
Country: England
Language: English
Volume: 13
Issue: 4
Pages: 393-403

Researcher Affiliations

Snow, D H
  • Animal Health Trust, Newmarket, Suffolk, UK.
Frigg, M

    MeSH Terms

    • Administration, Oral
    • Analysis of Variance
    • Animals
    • Ascorbic Acid / administration & dosage
    • Ascorbic Acid / blood
    • Ascorbic Acid / pharmacokinetics
    • Biological Availability
    • Circadian Rhythm
    • Drug Tolerance
    • Female
    • Horses / metabolism
    • Injections, Intramuscular / veterinary
    • Injections, Intravenous
    • Injections, Subcutaneous / veterinary
    • Male


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