Field of the invention
The present invention related to effective delivery of drugs through the inhalation route for treatment of tuberculosis including drug resistant tuberculosis.
Background of the invention
Tuberculosis remains to be an enormous problem world over and in spite of availability of good chemotherapy, still the number of cases of tuberculosis and the problem of drug resistance is on the rise. The limitations of present antitubercular chemotherapy are the toxic side effects of the drug, long duration of therapy, malabsorbtion, drug interactions, cost of therapy and problem of drug resistance especially multi drug resistant tuberculosis. In drug resistance, the MIC level of various anti tubercular drugs against Mycobacterium tuberculosis become very high which are not achievable by the usual therapeutic dosages of these drugs in their oral or parentral form. Dosages required to achieve these high levels cannot be administered due to their toxicity & side effects.
Attempt has been made by others to modify various formulations of antitubercular drugs so as to improve the tolerance and reduce the side effects. Attempts have also been made to minimize drug interaction, to improve the drug level but these have failed since it is not possible to achieve those levels, which could handle the problem of drug resistant bacilli. Short course chemotherapy has been devised by using high dosages of antitubercular drugs, but still the therapy remains to be of minimum 6-9 months. It needs to be brought down to the shortest possible period but through conventional dosages it is not possible, as these dosages cannot be increased further. A brief summary of the prior art in the treatment of tuberculosis is given below.
Rikimaru T, Oizumi K. in their publication titled : Aerosolized therapy with streptomycin and steroids in treatment of bronchial stenosis due to endobronchial tuberculosis. Journal Kekkaku December; 74(12):873-7, 1999 studied the role of aerosolized therapy with streptomycin and steroids in treatment of bronchial
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stenosis due to endobronchial tuberculosis and found aerosol therapy with these drugs useful in management of these cases.
Yokota S, Miki K. : Effects of INH (Isoniazid) inhalation in patients with endobronchial tuberculosis, J. Kekkaku, 74(12):873-7, 1999: Studied the effects of INH (Isoniazid) inhalation in patients with endobronchial tuberculosis and concluded that INH inhalation in addition to standard chemotherapy of lung tuberculosis is useful to prevent bronchial stenosis in these patients
Dutt M, Khuller G.K.: Chemotherapy of Mycobacterium tuberculosis infections in mice with a combination of isoniazid and rifampicin entrapped in Poly (DL-lactide-co-glycolide) microparticles. J. Antimicrob Chemother, June; 47(6):829-35. 2001: studied the effect of Chemotherapy of Mycobacterium tuberculosis infections in mice with a combination of isoniazid and rifampicin entrapped in poly (DL-lactide-co-glycolide) micropartilces delivered through aerosol and concluded that these offer and advantage over the conventional chemo therapy
O'Hara P and Hickey AJ : Respirable PLGA Microspheres containing rifampicin for the treatment of Tuberculosis manufacture and characterization. Journal Pharmaceutical Research, Vol 17 No. 8, 2001: studied the role of respirable PLGA microspheres containing rifampicin for the treatment of tuberculosis: manufacture and characterization, in an infectious disease model and concluded that respirable rifampicin loaded PLGA microspheres were produced by both solvent evaporation and spray drying methods. These particles are being evaluated in an animal model of tuberculosis
Sacks LV, Pendle S, Orlovic D, Andre M, Popara M. : Adjunctive salvage therapy with inhaled aminoglycosides for patients with persistent smear-positive pulmonary tuberculosis ; Journal Clin Infectious Disease January; 32(1): 44-9, 2001: studied the role of adjunctive salvage therapy with aerosolized inhaled aminoglycosides( Gentamicin or kanamycin ) in patients with persistent smear-positive pulmonary tuberculosis and concluded that adjunctive aerosol

aminoglycosides may expedite sterilization of sputum among certain patients with refractory TB and diminish the risk of transmission
Sharma R, Saxena D, Dwivedi AK, Misra A.: Inhalable microparticles containing drug combinations to target alveolar macrophages for treatment of pulmonary tuberculosis. Journal Pharm Res. October 18(10):1405-10, 2001: studied the inhalable microparticles containing drug combinations to target alveolar macrophages for treatment of pulmonary tuberculosis in experimental animals and concluded that inhalable micro particles containing multiple anti-TB drugs offer promises of dose and dosing- frequency reduction, toxicity alleviation, targeting macrophages resident persistent mycobacteria
Suarez S, O' Hara P, Kazantseva M, Newcomer CE, Hickey AJ. : Respirable PLGA microspheres containing refampicin for the treatment of tuberculosis: Screening in an infectious disease model : Journal Pharm Res. September 18(9): 1315-9, 2001: studied the manufacture and characterization of Respirable PLGA Microspheres containing rifampicin for the treatment of tuberculosis and they found that respirable rifampicin loaded PLGA microspheres were produced by both solvent evaporation and spray drying methods.
Suarez S, O' Hara P, Kazantseva M, New comer CE. : Airways delivery of rifampicin microparticles for the treatment of tuberculosis. Journal Antimicrob Chemother September. 48(3):431-4, 2001: studied the airways delivery of rifampicin microparticles for the treatment of tuberculosis and they supported the potential of R-PLGA delivered to the lung for treatment of pulmonary tuberculosis in experimental animals.
Pandey R, Sharma A, Zahoor A, Sharma S, Khuller GK, Prasad B.: Poly (DL-lactide-co-glycolide) nanoparticle-based inhalable sustained drug delivery system for experimental tuberculosis. Journal Antimicrob Chemother, November; 2003: studied the role of poly (DL-lactide-co-glycolide) nanoparticle-based inhalable

sustained drug delivery system for experimental tuberculosis and concluded that Nebulization of nanoparticles-based ATDs forms a sound basis for improving drug bioavailability and reducing the dosing frequency for better management of pulmonary tuberculosis in experimental animals.
Sharma A, Sharma S, Khuller GK: Lectin-functionalized poly (lactide-co-glycolide) nanoparticles as oral/aerosolized antitubercular drug carriers for treatment of tuberculosis; J Antimicrob Chemother. 2004 Oct;54(4):761-6. Epub 2004 Aug 25: studied the Lectin-functionalized poly (lactide-co-glycolide) nanoparticles as oral/aerosolized antitubercular drug carriers for treatment of tuberculosis and concluded that : WGA-functionalized PLG-NPs could be potential drug carriers for antitubercular drugs through the oral as well as aerosol route for effective TB control in experimental animals
Sherry E, Warnke PH: Successful use of an inhalational phytochemical to treat pulmonary tuberculosis: a case report; Phytomedicine. 2004 Feb;11(2-3):95-7 reported the successful use of an inhalational phytochemical to treat pulmonary
tuberculosis.
Vyas SP, Kannan ME, Jain S, Mishra V, Singh P : Design of liposomal aerosols for improved delivery of rifampicin to alveolar macrophages; Int J Pharm. 2004 Jan 9;269(1):37-49: studied the design of liposomal aerosols for improved delivery of rifampicin to alveolar macrophages in experimental animals and concluded these results suggest that the ligand-anchored liposomal aerosols are not only effective in rapid attainment of high-drug concentration in lung with high population of alveolar macrophages but also maintain the same over prolonged period of time.
Pandey R, Khuller GK: Antitubercular inhaled therapy: opportunities, progress and challenges; J Antimicrob Chemother. 2005 Apr;55(4):430-5. Epub 2005 Mar 10. In his review article on the Antitubercular inhaled therapy : its opportunities, progress and challenges and concluded that The obvious advantages of inhaled

therapy include direct drug delivery to the diseased organ, targeting to alveolar macrophages harboring the mycobacteria, reduced risk of systemic toxicity and improved patient compliance but also said that several key issues such as patient education, cost of treatment, stability and large scale production of drug formulations, etc. need to be addressed before antitubercular inhaled therapy finds its way from theory to clinical reality
Detailed Description of the Invention
The present invention as opposed to the prior art discloses an approach of delivering dugs through inhalation route in smaller dosages directly to the target organ i.e. lung, In human beings This minimizes the side effects, toxic reactions and allows concentration of drug reach those levels, which are above MIC of the particular drug addressing the problem of drug resistance, minimizing drug interactions and reducing the cost of therapy.
The particle sizes of the drugs are so selected so as to enable the inhaled ATD to reach almost all parts in the lungs. The selected particle size range is 0,5 micron to 11 microns which ensure that larger particles 4.7 -11 micron reach the upper airways , the smaller ones reach the lower airways: 3.3-4.7 micron in trachea and proximal bronchus, 2.1 to 3.3 micron in secondary bronchus, 1.1 to 2.1 micron in terminal bronchus and 0.5 to 1.1 micron in the alveoli.
Antiasthma drugs are selected from salbutamol, salmeterol, formeterol, ipratropium, tiotropium, beclamethasone, budesonide, fluticasone etc. The particle sizes are selected in the range below 7.2 microns.
Various other drugs which have been tried as inhalants include antibiotics e.g. tobramycin, ciprofloxacin, aztreonam , meropenem etc have also been tried in lung infections

IFN a and IFN y may also be combined with ATD in the particle size range disclosed above and delivered by the inhaled route to synergistically work.
The formulations with the drugs in the particle size ranges also use various combinations of the drugs e.g. rifampicin and isoniazid; rifampicin, isoniazid and ethambutol ; rifampicin, isoniazid , pyrazinamide and ethambutol ; rifabutin and isoniazid; rifabutin .isoniazid and ethambutol; rifabutin, isoniazid and pyrazinamide; rifabutin .isoniazid .ethambutol and pyrazinamide.
Comparative human bioavailability data of oral and inhaled antitubercular drugs both in the blood and BAL fluid and alveolar macrophages in healthy human volunteers have been studied. Half the healthy volunteers were given anti tubercular drugs (rifampicin, isoniazid & pyrazinamide) in inhaled form together in a single capsule as described in the present invention and the other half through oral route. Blood and BAL samples were taken at a definite interval and analyzed using high performance liquid chromomatography on c18 column. The drug levels in blood plasma were significantly less in the volunteers in the inhaled group as compared to those given drug through oral route. This will ultimately have an impact on toxic and side effects of drugs which will be less through inhalational route
Bioavailability of inhaled antitubercular drugs was significantly greater inside the alveolar macrophages and in broncho alveolar lavage (BAL) fluid signifying greater concentration of the drug at the target organ i.e. lung. The concentration of the drug was so high, both in extra cellular (BAL fluid) and intra cellular (alveolar macrophages) (more than 100 times) which would make it higher than MIC to these drugs in resistant cases, making it a useful option in treatment of drug resistant tuberculosis. The levels were highest for isoniazid followed by rifampicin and thereafter pyrazinamide.

The study was conducted on a large number of resistant cases and included 58 cases out of which inhaled drug along with oral drugs was given in 30 cases and only oral in 28 cases. The study has completed one year and the results were significantly better in the inhaled group as compared to the oral group and the side effects were also less in the former. Some of the cases who had earlier failed to respond to all possible anti tubercular drugs available, responded to therapy (80%) when inhaled drugs were added to the regimen
We have used three drugs (Rifampicin, Isoniazid & Pyrazinamide) in a fixed dose combination in a single capsule whereas other studies have included only single drug mostly in nebulized form. When the particle sizes are chosen in the range disclosed in the invention, no carrier molecule was found necessary and high levels of drug were obtained in the target organ in formulations to be delivered by other routes carriers are required. Thus the inhaled therapy is safer (spares vital organ e.g. liver, kidneys, brain etc) cheaper, better tolerated, has less side effects and is more effective.
We have therefore surprisingly found that when the particle sizes of the drugs are
selected in the range of 0.5 microns to 11 microns, it is possible to deliver the
drug directly to the lungs by the inahalation route which leads to advantages in
antitubercular therapy such as Increased concentration of antitubercular drugs at
the target site (alveolar macrophages and extracellulary) in the lungs, reduced
dosages, decreased side effect of the antitubercular drugs, reduction in the
duration of therapy, definitive role in drug resistant pulmonary tuberculosis even
when resistant to the same drugs by oral route and advantages in conditions of
malabsorbtion of drugs e.g. HIV with tuberculosis and in patients with HIV due to
nointeraction with antiretroviral therapy. ^ AA ,a n, „j