What are the drugs for treating uterine contractions?

During pregnancy, women should fully understand their own situation in each stage, especially in the late pregnancy. If they find that they have uterine contractions, they should seek medical attention in time. Some women have uterine contractions too early, which is still very dangerous for the fetus. So what are the drugs for treating uterine contractions? The choice of drugs for treating uterine contractions should be divided into two aspects, and no matter which one is chosen, it should be done under the guidance of a doctor.

What are the drugs that inhibit uterine contractions? According to the mechanism of action, uterine contraction inhibitors can be divided into two categories: the first category: blocking or inhibiting the release of synthetic uterine contraction substances, such as ethanol, prostaglandin synthase inhibitors, etc.; the second category: changing the responsiveness of the uterine muscle to uterine contraction substances such as magnesium sulfate, β2-adrenergic receptor stimulants, antihypertensive drugs, etc. If they cannot prevent the progress of labor, they should be discontinued immediately. The commonly used drugs are as follows:

1. Indomethacin (Indomethacin): Prostaglandins stimulate uterine contraction and cause the cervix to soften and become receptive. Indomethacin can inhibit prostaglandin synthase and thus inhibit the synthesis of prostaglandins. The usual dose is 25 mg orally every 6 hours; or 50 mg rectal suppository once every 12 hours until uterine contractions stop.

2. Magnesium sulfate: Magnesium ions can compete with calcium ions to enter the sarcoplasmic reticulum and can directly act on muscle cells, reducing the potential difference of the muscle cell membrane without producing muscle contraction. The inhibitory effect is related to the dose. When the serum magnesium concentration is 2-4mmol/L (4-8mEq/L), it can completely inhibit the natural contraction of the uterine muscle and the uterine contraction caused by oxytocin.

3. β2-adrenergic receptor stimulants: β2-receptors are mainly found in uterine blood vessels, bronchi and diaphragm smooth muscles. The drug acts directly on the receptors on the smooth muscle cell membrane and after binding to the corresponding receptors, it activates adenylate cyclase and increases the cyclic adenosine monophosphate (cAMP) content in the smooth muscle cells, inhibits the release of calcium from the sarcoplasmic reticulum, reduces the calcium content in the cytoplasm, relaxes the uterine muscles and inhibits uterine contractions.

4. Calcium antagonists: The main function is to prevent calcium ions from entering the cell membrane, prevent the release of calcium from the intracellular muscle fiber membrane and increase the excretion of calcium from the smooth muscle, thereby reducing the calcium content in the cytoplasm and relaxing the uterine muscle. Among this type of drugs, the most effective is nifedipine (nifedipine) with a dose of 10 mg, taken orally 3 times a day. It works faster when taken sublingually and can reduce the amplitude of uterine contractions and muscle tension. However, it can cause peripheral vasodilation, slowing of atrioventricular conduction and subsequent reflex tachycardia, headache, hot flashes, and reduced uteroplacental blood flow.