Ergot alkaloids: Nursing pharmacology

Ergot alkaloids are a group of medications produced by the fungus Claviceps purpurea. Ergot alkaloids, or simply ergots, include methylergonovine, which can be used to prevent or treat postpartum hemorrhage.

Other ergots include ergotamine, which can be used to treat severe migraines, as well as bromocriptine, which can be used to treat Parkinson disease.

Now, ergot alkaloids have similar structure to the neurotransmitters norepinephrine, serotonin, and dopamine. As a result, they can act as antagonists on alpha-adrenergic receptors on smooth muscle cells, as well as agonists of serotonin and dopamine receptors, mainly found in the brain.

In particular, methylergonovine primarily acts on alpha-adrenergic receptors on the uterus, increasing the tone, and rate of uterine rhythmic contractions, as well as inducing vasoconstriction.

For this reason, methylergonovine can be administered intramuscularly, and less frequently orally or intravenously, usually after delivery of the placenta to decrease bleeding, and promote uterine involution.

Typically, methylergonovine is used as second-line after safer medications like oxytocin have failed to control the bleeding. However, methylergonovine may cause significant side effects.

The most common ones include gastrointestinal symptoms like nausea or vomiting, as well as abdominal pain and diarrhea. Another important side effect is related to uterine hyperstimulation, where there’s too much contraction, and may result in uterine tetany.

Some clients may develop allergic reactions, such as a skin rash or swelling of the face, lips, or tongue; or present with headaches, dizziness, vertigo, and tinnitus.

Cardiovascular effects are mainly associated with intravenous administration, and include hypo- or hypertension, Raynaud phenomenon, palpitations, angina, and arrhythmias.

Ergot toxicity may cause ergotism, which mainly presents with nausea, vomiting and dyspnea; in addition, hypoperfusion of the limbs may lead to numbness, tingling, and muscle pain, or even gangrene involving the hands and feet. And finally, ergotism may lead to sustained vascular spasms, seizures, hallucinations, and even coma.

Now, methylergonovine is contraindicated in clients who have previously developed allergic reactions to ergot-derived medications.

In addition, due to its vasoconstrictive effects, methylergonovine is contraindicated in clients with cardiovascular disease, hypertension, preeclampsia, or eclampsia as well as during pregnancy, since it may stimulate contraction of the uterus and lead to decreased placental blood flow, premature labor, or even miscarriage.