The types of tocolytics that have been used include:
Betamimetics
Prostaglandin inhibitors
Magnesium sulphate
Calcium antagonists
Oxytocin blocking agents
Hydration
Antibiotics
Betamimetics
How betamimetics are given
Side effects of betamimetics - mother
Side effects of betamimetics - baby
Betamimetics are the most common tocolytic medications given to women to suppress preterm labour contractions. The types usually used are called 'ritodrine' or 'salbutamol' (others can be 'isoxsuprine', 'fenoterol' and 'terbutaline'). These drugs are 'smooth muscle relaxants' and are aimed at relaxing the muscles of the uterus so they do not contract. Interestingly, the same medications are used in lesser concentrations to treat people suffering from asthma (for example salbutamol or 'Ventolin'), as the medication will also 'relax' the muscles of the lungs to help the person breathe more easily.
Of all the tocolytic medications, betamimetics have been the most studied in research trails. Overall the research shows they tend to delay labour for short periods of up to 48 hours or more. The longer betamimetics are used (several days or weeks), the less effective they can become. In many cases the labour would have stopped on its own anyway but many caregivers will use the medications just in case the labour continues.
The temporary delay may assist extremely preterm babies who would benefit from being in the womb a little longer, the delay may facilitate the administration of steroid injections to the mother (being most effective after 48 hours). The betamimetics could also allow time for the mother to transfer to a hospital with a level 3 intensive care nursery (if this was preferred or needed).
How betamimetics are given. Betamimetics are given through a drip in the woman's vein. They are administered through a special machine called an 'infusion pump'. The pump measures the precise dose of the drug given.