Beta-2 stimulant

The beta-2 stimulants are uterine relaxants. They are also called adrenergics or adrenomimetics. They are relatively old, and have been used since the 1970s.

How do the beta-2 stimulants work?

These medicines are administered intravenously. They reduce uterine contractions for approximately 48 hours. To do this they bind to a smooth muscle cell receptor and cause the muscle cell to relax. Their action is not limited to the smooth muscle of the myometrium, the uterine muscle. They also act on other smooth muscle fibres, for example, in the lung. They therefore have a bronchodilating effect. For this reason they are also used in asthma.

Do they have contraindications or precautions?

Occasionally the beta-2 stimulants can increase heart rate in the mother and unborn child. Hand tremor, sweating or agitation can also occur after they have been administered.

Source: Interview with Dr Philippe Deruelle, gynaecologist at the Lille University Hospital, 8 July 2011