WO2014080378A1

WO2014080378A1 - Phenothiazine derivatives and their use against tuberculosis

Info

Publication number: WO2014080378A1
Application number: PCT/IB2013/060403
Authority: WO
Inventors: Moegamat Anwar Jardine; Muazzam JACOBS
Original assignee: University Of Cape Town
Priority date: 2012-11-26
Filing date: 2013-11-26
Publication date: 2014-05-30
Also published as: RU2015125300A; CN104812394B; ZA201503466B; RU2663289C2; CN104812394A

Abstract

Tricyclic derivatives of formula (1), wherein R₁ may be an alkyl sulphonate or sulphonamide group, are useful as antimicrobial agents. The derivatives are optionally substituted wherein R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y may be N, or C; X may be S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyl ring. The tricyclic derivatives, such as phenothiazine derivatives, may be used in treating tuberculosis, especially drug sensitive and resistant forms of tuberculosis. The derivatives of the invention may be used independently or in combination with known anti-tubercular drugs such as isoniazid, ethionamide and ethambutol, and the combination may be administered as a single dose, or as two independent dosages. The tricyclic derivatives may also be used for the manufacture of a medicament for treating tuberculosis.

Description

PHENOTHIAZINE DERIVATIVES AND THEIR USE AGAINST TUBERCULOSIS

FIELD OF THE INVENTION This invention relates to tricyclic derivatives of phenothiazines, phenoxazines, phenazines, acridines, oxazepines, diazepins, xanthenes, thioxanthenes and uses thereof.

BACKGROUND TO THE INVENTION

The phenothiazine antipsychotic and antihistaminic drugs prochlorperazine, chlorpromazine, and promazine have demonstrated a synergistic interaction with a wide spectrum of antimicrobial agents. The minimum inhibitory concentrations of these antibiotics were sometimes reduced up to 8,000-fold in the presence of the phenothiazines.

Phenothiazines are also known to increase the NADH/NAD ratio of Mycobacterium tuberculosis via the inhibition of type II NADH:menaquinone oxidoreductase. In this way they are able to increase the reduced state of a cell and are capable of acting synergistically with drugs that require mycothiol for activation such as isoniazid and ethionamide. These combination therapies assist in limiting the emergence of resistance to antimicrobial agents. It has been proven that phenothiazines, such as thioridazine are active against Multi- and Extremely Drug Resistant forms of Mycobacterium tuberculosis.

Phenothiazines have demonstrated a wide range of biological activities, though they are primarily used as neuroleptic drugs. These neuroleptic attributes limit antimicrobial utility of these drugs in diseases such as tuberculosis as they may induce undesirable central nervous system (CNS) side effects at a mycobactericidal dose. There is thus a need for modified phenothiazine derivatives which exhibit no or minimal undesirable CNS side effects.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a tricyclic derivative of formula (1 ),

(1 ) wherein Ri is an alkyl sulphonate or sulphonamide group; R₂ is hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyl ring. When (1 ) is a phenothiazine derivative, then R₂ is not H.

In a preferred embodiment of the invention R is (CH₂)_nSO₃M, wherein n = 1 , 2, 3 or 4 and M = Na, K or H or R is SO₂Ar, with Ar optionally substituted; R₂ is H, CI, Br, SMe, C(O)CH₃ or CF₃; Y is N or C and X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyl ring. The substituents on the Ar when R is SO₂Ar include ortho and para substituents selected from NO₂, NH₂, SO₃M, CO₂R, where M = Na, K or H and R = alkyl.

Further features of the invention provide for the tricyclic derivative to be selected from: Phenothiazines

When n=3, R₂ is not H

Phenazines Phenoxazines Thiazepines

Thioxanthenes Xanthenes H, CI, CF₃, SMe, C(0)CH₃ 2,3 or 4

Still further features of the invention provide for the tricylic derivative to be selected from:

The invention provides for tricyclic derivatives of formula (1 ) as defined above as including phenothiazine derivatives of formula (1 ) wherein n = 3 and R₂ = H, for use in treating tuberculosis, preferably drug sensitive and resistant forms of tuberculosis, for the derivatives for use in treating tuberculosis, wherein the derivative is used independently or in combination with known anti-tubercular drugs.

The invention also provides for a method of treatment of tuberculosis, wherein the method comprises administering a therapeutically effective amount of the tricyclic derivative of formula (1 ) as defined above and including a phenothiazine derivative of formula (1 ) wherein n = 3 and R₂ = H, to a patient in need thereof, for the administration of the derivative to be in combination with a second anti-tubercular drug, both of which may be administered as a single dose, or as two separate dosages.

Further features of the invention provide for the anti-tubercular drugs to be selected from isoniazid, ethionamide, ethambutol, pyrazinamide,rifampicin, amikacin, kanamycin, capreomycin, viomycin, enviomycin, ciprofloxacin, levofloxacin, moxifloxacin, rifabutin, clarithromycin, linezolid, thioacetazone, prothionamide.

The invention further provides for the use of a tricyclic derivative of formula (1 ) as defined above and including a phenothiazine derivative of formula (1 ) wherein n = 3 and R₂ = H, in the manufacture of a medicament for treating tuberculosis.

The invention yet further provides a medicament in unit dose form, characterised in that each unit dose includes a tricyclic derivative of formula (1 ) as defined above and including a phenothiazine derivative of formula (1 ) wherein n = 3 and R₂ = H, and a second anti-tubercular drug.

Further features of the invention provide for the anti-tubercular drug to selected from isoniazid, ethionamide, ethambutol, pyrazinamide, rifampicin, amikacin, kanamycin, capreomycin, viomycin, enviomycin, ciprofloxacin, levofloxacin, moxifloxacin, rifabutin, clarithromycin, linezolid, thioacetazone, prothionamidea. BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described, by way of example only with reference to the accompanying figures in which:

Figure 1 shows anti-mycobacterial activity of isoniazid (INH), thioridazine (TZ) and synthesized phenothiazine derivatives C3, C4, C31 , C32 and C33 directly against M.tb H37Rv.gfp using the GFAP microplate assay and a table summarising the derived MIC₅o values;

Figure 2 shows activity of test compounds against intracellular M.tb

H37Rv where infected macrophages were treated with INH, TZ and test compounds respectively, for five days at the indicated concentration;

Figure 3a and 3b show results of a radio-ligand binding assay indicating no activity in terms of binding to dopaminergic- receptor subtypes D1 , D2, D3 and serotonergic-receptor subtypes 5-HT1 A, 5-HT2A, and 5-HT2C;

Figure 3c is a graphical representation of percentage inhibition of C3

(D50031 ) against dopamine and serotonin inhibitors;

Figure 3d is a graphical representation of percentage inhibition of C4

(D50032) against dopamine and serotonin inhibitors;

Figure 3e is a graphical representation of percentage inhibition of C31

(D50033) against dopamine and serotonin inhibitors; is a graphical representation of percentage inhibition of C32(D50034) against dopamine and serotonin inhibitors; and Figure 3g is a graphical representation of the percentage inhibition of

C33(D50035) against dopamine and serotonin inhibitors;

Figure 4 is a graph showing changes in body weight on a daily basis of mice receiving daily doses of 100 mg/kg of either C3 or C4 and mice left untreated, over a 14 day period; and

Figure 5 are graphs showing organ weights of mice at the end of a

14 day experiment, after being treated with a daily dose of 100 mg/kg of either C3 or C4 and mice left untreated.

DETAILED DESCRIPTION WITH REFERENCE TO THE FIGURES

Tricyclic derivatives of the general formula (1 ) are provided, as illustrated below,

(1 ) wherein Ri is an alkyl sulphonate or sulphonamide group; R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyi ring. When (1 ) is a phenothiazine derivative, then R₂ is not H. In a preferred embodiment of the invention R is (CH₂)nS03M, wherein n = 1 , 2, 3 or 4 and M = Na, K or H or R is S0₂Ar with Ar optionally substituted; R₂ is H, CI, Br, SMe, C(0)CH₃ or CF₃; Y is N or C and X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyi ring.

The substituents on the Ar when R is SO₂Ar include ortho and para substituents selected from NO₂, NH₂, SO₃M, CO₂R, where M = Na, K or H and R = alkyl.

The following compounds represent preferred embodiments of the tricyclic derivatives of the general formula (1 ):

Phenothiazines

When n=3, R₂ is not H

Phenazines Phenoxazines Thiazepines

Thioxanthenes

F₃, SMe, C(0)CH₃

In a more preferred embodiment, the tricyclic derivatives of the general formula (1 ) may be selected from:

A process for preparing /V-alkylsulfonates of phenothiazine involves:

(a) the preparation of the phenothiazine anion, and

(b) the reaction of said anion with cyclic alkyl sulfonates, such as 1 ,3-propane sultone or 1 ,4-butane sultone as generally described in United States Patent number 7,855,287. A less efficient, multistep synthetic method was published earlier in the Journal of Physical Chemistry, 1986, 90, 2469-2415.

The phenothiazine derivatives of the invention have been shown to have limited toxicity against primary macrophage cultures as well as limited psychotropic activity.

The anti-schizophrenic activity of phenothiazine drugs are thought to involve the blockade of synaptic dopamine receptors in the brain. It has been shown by means of molecular space filing models that favourable Van der Waal's interactions between the side chain amino of phenothiazines and the 2- substituent on ring A can promote a conformation mimicking that of dopamine. Thus modifications that deviate from this favoured orientation would diminish dopamine receptor binding and reduce CNS effects.

Standard dopamine and serotonin inhibition studies of the compounds of this invention have revealed complete inactivation of binding, thus suggesting a complete abolishment of CNS activity. The compounds of the invention have shown significant mycobacterial inhibition against virulent Mycobacterium tuberculosis, showing a minimum inhibitory concentration (MIC₅o) of ~6-12μg/ml in direct killing assays.

From in vitro studies it has been conclusively shown that alkyl sulphonate derivatives of the phenothiazine derivatives, as shown above, are very effective at killing virulent M. tuberculosis when in direct contact with the bacillus indicating that the compounds bypass mechanisms that M. tuberculosis employs to induce tolerance such as efflux pumps. Moreover, it has been well established that M. tuberculosis persist within phagosomes of macrophages, the primary host cells of bacilli, where specific evasion strategies allows it to prevent fusion with lysomes thus preventing degradation by lysosomal enzymes. One of the key challenges for potentially new drug candidates is to transverse several of these membrane systems to reach the target organism and induce killing. Data obtained clearly demonstrate that these compounds of the invention have the ability to cross all membrane systems and inhibit M. tuberculosis replication. Compared to thioridazine which is neuroleptic and cytotoxic, these compounds are superior in terms of cytotoxicity and are devoid of neuroleptic properties.

Phenothiazines, are known to improve efficacy of isoniazid in latency models in vivo and in vitro. However, pharmacokinetics and pharmacodynamics that favour its psychotic attributes have precluded its utility as an antimicrobial drug in vivo.

The phenothiazine derivatives of the present invention may be used independently or in combination with known anti-tubercular drugs such as 1 st line drugs; ethambutol, isoniazid, pyrazinamide, rifampicin; 2nd line drugs; aminoglycosides (e.g., amikacin, kanamycin), polypeptides (e.g., capreomycin, viomycin, enviomycin); fluoroquinolones (e.g., ciprofloxacin, levofloxacin, moxifloxacin), thioamides (e.g. ethionamide, prothionamide); 3rd line; rifabutin, macrolides (e.g., clarithromycin), linezolid, thioacetazone, thioridazine, arginine, vitamin D and R207910.

The potential synergistic effects of this type of combination therapy are believed to be especially suitable for drug sensitive and resistant forms of M. tuberculosis.

The invention provides for a method of treatment of tuberculosis, wherein the method comprises administering an effective amount of the tricyclic derivative of the invention to a patient in need thereof. In one embodiment of the invention the administration of the compound is carried out in combination with a second anti-tubercular drug. The administration of this combination treatment is carried out by administering both the tricyclic derivative of the invention and the second anti-tubercular drug as a single dosage treatment or the administration is carried out as two consecutive separate dosages.

The invention further provides for the use of a tricyclic derivative of the invention for the manufacture of a medicament for treating tuberculosis. The medicament is manufactured as a solid oral dosage form, being a tablet, pill or capsule, or as a liquid oral dosage form, or as an aerosolized powder for pulmonary delivery, comprising both the tricyclic derivative and a second anti-tubercular drug, or each active ingredient separately to be administered consecutively.

The medicament having a combination of active ingredients being the tricyclic derivative and second anti-tubercular drug will preferably be in unit dose form. That is to say that both active ingredients will preferably be contained in a single tablet, pill, capsule or the like. Providing both active ingredients in a unit dose simplifies administration to patients, particularly when patients are required to self-administer the medicament. This also results in improved patient compliance and less likelihood of drug-resistant microbial forms developing as a result of partial or non-compliance with dosage regimens.

The chemically modified phenothiazines of the present invention retain antimicrobial activity and are non-toxic to macrophage cells. It will be appreciated by those skilled in the art that the new phenothiazine will have altered pharmacokinetics and pharmacodynamics across the blood brain barrier and as such minimise or exclude psychotic effects. It will further be appreciated that there are numerous modifications and variations of the embodiments of the invention that would be obvious to a person skilled in the art which are deemed to be within the scope of the invention, the nature of which is to be determined from the above description and the examples. Examples

Phenothiazine derivatives display direct anti-bacterial activity against M. tuberculosis in culture

Five compounds namely C3, C4, C31 , C32 and C33 (shown below) were evaluated against M. tuberculosis using the GFP microplate assay (GFPMA) to screen for the bactericidal/bacteriostatic activity of the phenothiazine derivative

Outcomes were compared with the known phenothiazine derivative thioridazine (TZ) and the first-line drug isoniazid (INH), which were used as positive controls for anti-mycobacterial efficacy. The results obtained have shown that all the test compounds, except for C33, displayed a dosage dependent inhibitory effect on the growth of M.f£>-H37Rv.gfp and the derived MIC50 values are summarised (Figure 1 ). The MIC50 of INH and TZ was similar to published data. Significant antitubercular activity was demonstrated for C3 and C4, which had the lowest MIC as well as for C31 and C32.

Phenothiazine derivatives are non-toxic for bone marrow derived macrophages in culture

The in vitro toxicity effects of C3, C4, C31 , C32 and C33 on bone-marrow- derived-macrophages (BMDM) at concentrations ranging between 0.1953 to 25 μg/ml was examined. Bone marrow was isolated from femurs of na^'ive C57BI/6 mice and macrophages cultured at 37 °C under 5% CO₂ until mature. The data showed that the compounds had no effect on the cell viability at all concentrations after 5 days of incubation (Table 1 , below). In contrast, TZ was toxic and induced cell death after 3 days of incubation (data not shown). After 5 days incubating with TZ, 1 00% cell death was observed at the concentrations ranged from 25 μ9/ιτιΙ to 6.25 μ9/ιτιΙ. INH was also included in the analysis at a range of concentrations between 0,00078 μ9/ιτιΙ to 0.1 μ9/ιτιΙ and was not found to be toxic (data not shown).

Table 1 : The cytotoxicity of test compounds on macrophages. Macrophages were treated for 5 days and cell viability assessed.

Intracellular inhibition of M. tuberculosis replication in macrophages by phenothiazine derivatives

To investigate whether compounds of the invention could transverse cell membrane systems and access intracellular bacilli to inhibit replication, M. tuberculosis was infected with BMDM and the infected cell cultures treated for 5 days with phenothiazine derivatives, C3 and C4. The inhibition of intracellular bacterial growth by either C3 or C4 was calculated and expressed as a percentage of the values obtained in untreated cell cultures. Simultaneously, the toxicity of the drugs on infected macrophages was also determined using the CellTiter-Blue Cell Viability Assay. The percentage of cell viability was calculated based on the values of infected cells (treated and untreated) versus the value of uninfected cells. As shown in Figure 2, both INH and TZ could inhibit more than 90% of intracellular M. tuberculosis growth at the concentrations of 1 μ9/ιτιΙ and 3 μ9/ιτιΙ respectively. Interestingly, both C3 and C4, tested at 25 μ9/ιτιΙ showed significant antibacterial activity of between 40-50 %, although being less efficient compared to INH and TZ. It is noteworthy that all the infected macrophages were almost completely viable after drug treatment. Thereafter, macrophages were lysed and supernatants plated for CFU determination.

Seratonin and Dopamine Binding Studies

The results of the radio-ligand binding assay indicated no activity in terms of binding to the dopaminergic-receptor subtypes D1 , D2, D3 and the serotonergic-receptor subtypes 5-HT1 A, 5-HT2A, and 5-HT2C. (Figures 3a- g). The benchmarked, unmodified phenothiazines, thioridazine and chlorpromazine were chosen as a point of reference. Almost complete abolishment of dopamine and serotonin receptor binding was achieved for the structural homologs, i.e. C3, C4, C31 , C32 and C33 (labelled as DS0031 , DS0032, DS0033, DS0034, DS0035).

Toxicity potential of the compounds C3 and C4 in a small animal model (C57BI/6 mice)

Toxicity of the phenothiazine derivatives C3 and C4 at a dose of 100 mg/kg as a maximum starting dose were evaluated and outcomes measured against known, clinically approved phenothiazine, thioridazine (TZ), or against no treatment.

Initial studies were conducted to evaluate the maximal tolerated dose of TZ in mice because of the variability of reported published data which ranged from 160 mg/kg to 20 mg/kg. The studies challenged 6-8 week old adult female C57BI/6 mice (n=10/group) with 100 mg/kg, 40 mg/kg, 20 mg/kg and 10 mg/kg by oral gavage and monitored animals for survival and measured change in body weight. In an initial sub-acute study TZ was administered once in a volume of 200 μΙ at onset of the experiment and survival and bodyweight changes monitored. It was found that a challenge dose of 40 mg/kg and 100 mg/kg was transiently toxic as animals presented with paralysis within 6 h. However, animals recovered within 24-48 h. Animals transiently lost weight but recovered after 3-4 days. Single dose administration of TZ did not induce mortality at any of the doses tested over a 2 week period.

To evaluate toxicity of single dose (100 mg/kg) administration of C3 and C4, the phenothiazine derivatives were administered by oral gavage in a volume in 200 μΙ. Similar to untreated animals, none of the animals showed significant weight loss over the 14 day period. Similarly, no animal loss on administration of a single dose of 20 mg/kg TZ was found. Mice displayed transient lethargy but recovered within 24 h. This single dose study was repeated with similar outcomes.

Next toxicity was evaluated in animals which received therapy on a daily basis. Briefly, mice (n=10-15/group) received either TZ (10 mg/kg or 20 mg/kg); C3 (100 mg/kg) or C4 (100 mg/kg) administered in 200 μΙ water by oral gavage on a daily basis. Changes in body weights were measured and recorded on a daily basis (Figure 4). The experiment was terminated after 14 days when all animals were humanely sacrificed and organs (heart, lung, brain, kidney, liver and spleen) removed and weighed (Figure 5). Blood was collected and serum stored for further analysis. Animals that did not receive any therapy initially gained bodyweight which thereafter stabilised. Animals which received a daily dose of 100 mg/kg showed rapid weight loss of approximately 10% in the first week after which it stabilised with possibility of recovering weight loss towards the end of the week 2. Measurement of organs in C3 and C4 treated animals showed a significant reduction in spleen weight in both therapy groups compared to untreated animals. All other organs remained unaffected.

The comparative toxicity profiles of C3 and C4 is significantly better than that of the clinically approved phenothiazine, TZ, even when the latter is tested at 10 fold lower dose concentration than either C3 or C4. While daily dose administration of either 100 mg/kg or 40 mg/kg TZ resulted in 100% mortality of animals within 48 h, all animals survived administration of C3 or C4 at 100 mg/kg. Nonetheless, although mice survived infection, C3 or C4 treated animals lost approximately 10% of their body weight. Of the organs assessed, brains, livers, lungs, kidneys and hearts showed normal weight distribution while spleens were significantly reduced. Overall, mice displayed no abnormal behaviour tolerated C3 and tolerated therapy over the 14day period.

It will be appreciated that there are numerous modifications and variations of the embodiments of the invention that would be obvious to a person skilled in the art which are deemed to be within the scope of the invention, the nature of which are to be determined from the above description and the examples.

Claims

CLAIMS:

wherein Ri is an alkyl sulphonate or sulphonamide group; R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyi ring and when (1 ) is a phenothiazine derivative, then R₂ is not H.

A tricyclic derivative as claimed in claim 1 wherein R is (CH₂)_nSO₃M, with n = 1 , 2, 3 or 4 and M = Na, K or H or R₁ is SO₂Ar, with Ar optionally substituted; R₂ is H, CI, Br, SMe, C(O)CH₃ or CF₃; Y is N or C and X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyi ring.

A tricyclic derivative as claimed in claim 2 wherein the Ar of SO₂Ar is optionally substituted in the ortho or para position with substituents selected from NO₂ , NH₂, SO₃M, CO₂R, where M = Na, K or H and R = alkyl.

A tricyclic derivative as claimed in any other the preceding claims wherein the tricyclic derivative is selected from: Phenothiazines

When n=3, R₂ is not H

Phenazines Phenoxazines Thiazepines

Thioxanthenes Xanthenes

F₃, SMe, C(0)CH₃

5. A tricyclic derivative as claimed in any one of the preceding claims wherein the tricyclic derivative is selected from:

wherein Ri is an alkyl sulphonate or sulphonamide group; R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyl ring, for use in treating antimicrobial infections.

A tricyclic derivative as claimed in claim 6 for use in treating tuberculosis.

A tricyclic derivative as claimed in claim 6, wherein the derivative is used independently or in combination with a second anti-tubercular drug.

A tricyclic derivative as claimed in claim 8 wherein the second anti- tubercular drug is selected from isoniazid, ethionamide, ethambutol, pyrazinamide,rifampicin, amikacin, kanamycin, capreomycin, viomycin, enviomycin, ciprofloxacin, levofloxacin, moxifloxacin, rifabutin, clarithromycin, linezolid, thioacetazone and prothionamide. 10. A method of treating tuberculosis which includes administering to a patient in need thereof a therapeutically effective amount of a tricyclic derivative of formula

wherein R is an alkyl sulphonate or sulphonamide group; R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyl ring. A method of treating tuberculosis as claimed in claim 10 wherein the tricyclic derivative is administered in combination with a second anti- tubercular drug either as a single unit dose or as separate dosages.

12. A method of treating tuberculosis as claimed in claim 1 1 wherein the second anti-tubercular drug is selected from isoniazid, ethionamide, ethambutol, pyrazinamide, rifampicin, amikacin, kanamycin, capreomycin, viomycin, enviomycin, ciprofloxacin, levofloxacin, moxifloxacin, rifabutin, clarithromycin, linezolid, thioacetazone and prothionamide.

13. Use of a tricyclic deri

wherein Ri is an alkyl sulphonate or sulphonamide group; R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyl ring, in the manufacture of a medicament for use in treating tuberculosis.

14. A medicament in unit dose form, characterised in that each unit dose includes a tricyclic d

(1 )

wherein Ri is an alkyl sulphonate or sulphonamide group; R₂ is a hydrogen, a halogen, a substituted alkyl group, a thioether or an acetyl group; Y is N, or C; X is S, SO, SO₂, N, O, CH₂, C(O), CO₂, NHCO, and ring B is a 6, 7 or an 8 membered cycloalkyi ring,

and a second anti-tubercular drug.

A medicament as claimed in claim 14 wherein the second anti- tubercular drug is selected from isoniazid, ethionamide, ethambutol, pyrazinamide,rifampicin, amikacin, kanamycin, capreomycin, viomycin, enviomycin, ciprofloxacin, levofloxacin, moxifloxacin, rifabutin, clarithromycin, linezolid, thioacetazone and prothionamidea.