Hazards of Altrenogest to Humans

An FDA report cautions veterinarians and horse owners about handling altrenogest (progestin) products.

Regular latex gloves might not offer enough protection when handling altrenogest products. iStock/Bojan89

Because equine veterinarians and their clients often handle altrenogest (progestin) hormones to assist in synchronizing timing of estrus in mares, it helps to remind everyone that there are risks with human contact and this medication. 

While a mare is usually given the supplement in an oral form, altrenogest is absorbed through the skin and mucous membranes of people. An FDA report provides cautions concerning who should not handle altrenogest (Regumate, Ovamed/Altresyn, Altren):

  • Women who are or suspect they are pregnant.
  • Anyone with thrombophlebitis or thromboembolic disorders or with a history of these events.
  • Anyone with cerebral-vascular or coronary-artery disease.
  • Women with known or suspected carcinoma of the breast.
  • People with known or suspected estrogen-dependent neoplasia.
  • Women with undiagnosed (unexplained) vaginal bleeding.
  • People with benign or malignant tumors that developed during the use of oral contraceptives or other estrogen-containing products.
  • Anyone with liver dysfunction or disease.

Anyone handling altrenogest products should do so with protective gloves; however, the FDA report noted that latex gloves might prove inadequate to protect against skin contact. Therefore, other impermeable glove materials should be used. Any contact of the drug with body, clothing or equipment should be countered with careful washing.

While dosing guns are available for Regumate to be used with gloves, there is another practical option for medication delivery. One useful practice tip for veterinarians to help clients with safe administration of altrenogest to their mares is to dispense a box of 100 red top blood tubes along with the medication. Each tube is then filled with the correct daily dose. This enables more than three months of treatment to be prepared at one time, thereby limiting the opportunities for inadvertent drug contact. Then, wearing a glove, the owner or person administering the daily medication can simply pop the top off the blood tube and top dress it onto the horse’s feed. The blood tubes are also reusable for further treatments.

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