Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Spiriva (Boehringer Ingelheim)
capsules containing 22.5 microgram as powder for inhalation
Approved indication: chronic obstructive pulmonary disease
Australian Medicines Handbook section 19.1.2
Ipratropium is an anticholinergic bronchodilator which is inhaled three or four times a day. Tiotropium has a similar mechanism of action, but only needs to be inhaled once a day.
Compared to ipratropium, tiotropium dissociates more slowly from M1 and M3 muscarinic receptors. Its bronchodilator effect begins within 30 minutes but can last for more than 24 hours.
In a placebo-controlled trial, 279 patients with stable chronic obstructive pulmonary disease inhaled tiotropium powder every morning for 13 weeks. Respiratory function tests (see 'Basic tests of respiratory function' Aust Prescr 2000;23:10-2) showed significant increases in forced expired volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate. The FEV1 and FVC increased within 30 minutes of the first dose. After one week of treatment, the FEV1 and FVC 24 hours after a dose were 10-13% greater than before treatment. The patients needed to use significantly less salbutamol than the 191 patients in the placebo group.1
Another study randomised 191 patients to use tiotropium powder once a day and 97 to use an ipratropium inhaler four times a day for 13 weeks. The increases in mean FEV1 and FVC were significantly greater with tiotropium than with ipratropium. Trough values (one hour before the next dose) of FEV1 and FVC were significantly larger with tiotropium than with ipratropium.2
The most common adverse effect of tiotropium is a dry mouth. This affects nearly 15% of patients.2
Tiotropium seems to be more potent than ipratropium, but the clinical advantage is unclear. The difference between the peak expiratory flow rates narrowed over the course of the comparative study.2At the end of the study the difference was approximately 10 L/minute which is not significant. Although patients taking tiotropium used significantly less salbutamol, the mean difference was less than one puff per day.2
