Terbutalin

Additional information

Terbutaline inhalation, tablets, or parenteral therapy is used for relief and prevention of bronchospasm in bronchial asthma or COPD. Parenteral terbutaline is also sometimes used in pregnant women to prevent premature labor.

Pharmacokinetics and dosing

In spite of terbutaline being a very hydrophilic substance, a small study on pharmacokinetics of bambuterol and terbutaline (4 men, 4 women), no differences were seen between men and women in distribution volume of terbutaline after parenteral administration [1].

Effects

No published studies with a clinically relevant sex analysis regarding the effects of terbutaline have been found.

Adverse effects

In a randomized, placebo-controlled trial, healthy volunteers (10 men, 10 women) were given either inhaled terbutaline 5 mg or placebo. Terbutaline lowered potassium levels more in women than in men (-15.4% in women vs. -8.5% in men after 1 h). After three hours however, no sex differences were seen. Terbutaline also increased heart rate in both sexes but the effect duration was greater in women. Terbutaline also caused prolongation of QTc in both sexes, an effect that was found to be greater, longer-lasting and more deleterious in women than in men [2]. However, terbutaline is not on the list of QT prolongation drugs with risk of Torsade de Pointes [3].

Reproductive health issues

Regarding teratogenic aspects, please consult Janusmed Drugs and Birth Defects (in Swedish, Janusmed fosterpåverkan).

Other information

In a study on inhalation technique using metered dose inhalers (33 men, 26 women), 75% of the participants had an incorrect inhalation technique, especially women, regardless of age. Only 4% of women and 43% of men had an acceptable inhalation technique. The authors speculate that this may add to the worse asthma prognosis in women, shown in a meta-analysis of six trials of randomly assigned asthma treatment [1].

Several studies have shown worse prognosis for women with asthma. In an observational registry study (416 men, 498 women), women were found to have more asthmatic symptoms, worse quality of life and require more health care due to their asthma [2]. In a Danish prospective study on hospitalization due to asthma (6104 men of whom 2.5% had asthma, 7436 women of whom 2.2% had asthma), women had a 1.7 higher relative risk to be hospitalized [3]. An observational study from Singapore found hospitalization due to asthma to be more common in boys than girls aged 0-4 years (boys/girls ratio 1.69). In adults aged 35-64 years, women were more hospitalized (men/women ratio 0.81) [4].