A formulation of tobramycin for nebulisation is now available for treating patients with cystic fibrosis. Tobi nebuliser solution (Pathogenesis) is licensed for long-term management of chronic pulmonary infection caused by Pseudomonas aeruginosa (see p39).
It is the first tobramycin product to be licensed for nebuliser use. Although nebulised antibiotics are commonly used in cystic fibrosis treatment, until now doctors wanting to use nebulised tobramycin have had to nebulise an IV formulation.
Tobi, which is intended for home treatment, is given on a “28 day on, 28 day off” cycle. It is given by hand-held Pari LC Plus nebuliser. Pathogenesis is supplying these nebulisers free of charge to patients prescribed the drug. Tobi will be supplied direct from the company.
Mr Andrew Whitehead (senior pharmacist, regional adult cystic fibrosis unit, Seacroft hospital, Leeds) said on December 20 that there was a small group of patients in whom the preservative in IV preparations caused bronchoconstriction on nebulisation. Tobi, which was preservative free, should be useful for this group. The new product would also probably be used in patients who were already nebulising tobramycin as it could be difficult to carry on using the IV formulation when a licensed nebuliser product was available, he said. However, this had cost implications as Tobi was more expensive than the IV formulations.
Nebulised antibiotics are used long term in cystic fibrosis to help maintain lung function in patients with established pseudomonal infection.
Two US trials with Tobi were reported earlier this year in the New England Journal of Medicine (1999;340:23). They involved a total of 520 patients. Treatment for 24 weeks was reported to improve lung function by an average of 10 per cent (compared with a 2 per cent decline in the placebo group) and to reduce hospitalisations. At a conference in October, 1999, follow-up data from these trials were reported, showing that, at two years, average lung function was around 5 per cent above baseline. The best results were in adolescents.
Dr Martin Scott (scientific advisor, Cystic Fibrosis Trust) welcomed the licensing of Tobi as it meant that doctors could now gain experience with the formulation. However, he said that there were no data on whether the new, more expensive, treatment was any better than routine nebulisation treatments. Dr Scott said that Tobi had been very successful in the US since its launch two years ago. But prescribing practice was different there in that nebulised antibiotics had not previously been used.
A small trial comparing Colomycin and Tobi is currently under way in the UK but results are not expected until mid-2000.