Narrowing with colistin inhalation

Question

Dear expert team,
as a female CF patient and an asthma patient with colonization of two strains of Pseudomonas (mucoid), I inhale every second month Cayston® (aztreonam), as I only hardly tolerate the other antibiotics for inhalation. In the interval-free month I got due to a cold ciprofloxacin 750mg 2 times a day for 3 weeks. In the third week a severe pneumonia occurred that had to be treated with an i.v. course for 1 month.
My question is now: would it make more sense to inhale alternately Cayston® and colistin? Does colistin have a positive effect against an infection even if it leads to a narrowing and the FEV1 is a bit worse or does it harm more in this case? Are there different products for tobramycin, that are better tolerable?
Many thanks for your help,
Best regards,
S.

Answer

Dear S.,
you have asked 3 questions with your mail.
In your first question you want to know, if it would make more sense in your case to inhalte alternately two antibiotics (28 days of Cayston® followed by 28 days of colistin) instead of the so-called on/off inhalation (28 days of inhalation followed by 28 days of pause). The question can be answered with "yes", if one puts the anti-bacterial drug effect (here against Pseudomonas aeruginosa) in the foreground. In case of patients with a good tolerability of the inhalative antibiotics, the "sequential" inhalative therapy is in general advantageous and acute infections can be better prevented. In case of a decision concerning the application of drugs, however, besides the effect also the side effect of the drug has always to be taken into account. The "basic law of therapy" reads: the side effect should never exceed the effect of a drug.
Therefore I return to your second question; in which you want to know if colistin can/should be used for inhalation in your case even if this drug leads to a narrowing of your bronchi. This question cannot be answered by us via the Internet, you need to talk in detail with your treating physician about this. Hereby, you should weigh the "pros and cons" together with your doctor, check you anti-asthmatic therapy (inhalative cortisone?), quantify the side effects of colistin via lung function, try to prevent narrowing of the bronchi e.g. with a "pre"-inhalation with a brocho-dilating drug (e.g. salbutamol or ipratropium bromide).
You could also try and test the inhaling antibiotic substance with a preparation from another company (colistin is available as Colifin® in 2 different concentrations). This can sometimes be helpful.
So I come to your third question. Here you want to know, if tobramycin for inhalation is licensed in different preparations. Yes, tobramycin for inhalation is available in several preparations, that can, if necessary, be tested by the patient for tolerability after consultation of the physician. These are:
- as humid inhalation: Tobi® 300, Bramitob® 300, Gernebcin® 160, Gernebcin 80
- as dry powder inhalation: Tobi Podhaler® (is however generally less tolerable by asthma patients than the humid inhalation)

You can see, that it deals here partly also with different drug concentrations (dosages).
Probably a lower dosage is better tolerable for you? If a lower dosage is sufficient for you concerning the effectiveness, can only be judged individually by your CF physician in charge.
Best regards,
Yours Dr. med. Christina Smaczny

24.06.2014