Tuberculoosis and antitubercular drugs

1. TUBERCULOSIS
and
ANTI-
TUBERCULAR
DRUGS
G Vijay Narasimha Kumar
Asst. Professor,
Dept. of. Pharmacology
Sri Padmavathi School of Pharmacy

2. DEFINITION
• A chronic bacterial infection caused by Mycobacterium
tuberculosis, usually characterized pathologically by the
formation of granulomas. The most common site of
infection is the lung, but other organs such as may be
involved.
• Other common names included “wasting disease” and the
“white plague.”
AETOLOGY
• TB is caused by Mycobacterium species mainly by
– Mycobacterium tuberculi which is aerobic atypical rod shaped
bacteria
• Other strains which causes TB are
– M.avium
– M.bovis ( Commonly caused by consumption of
unpasteurized milk)
– M.hominis

3. • Less common strains which causes TB are
– M.africanum
– M.microti
– Mpinnipeddi
– M.cannetti
• Less pathogenic strains are
– M.abscessus
– M.fortuitum
– M.chelonae
• Non pathogenic strains are M.smegmatis
• M.tuberculi also called as Koch’s bacilli or Acid Fast
bacilli

4. WHY TB IS A DREADFUL DISEASE ?
REASON FOR
DREADFUL DISEASE:
• Presence of Mycolic
acid (90’c’ atoms
arranged in a ring like
structure) in
Mycobacterium
species.
• Mycolic acids
 Prevents ,resists
against hydrophilic
and lipophilic
antibiotics, loss of
water, transport
of various
substances
 Helps in evading
from immune
system.

5. WHY IT CAN’T BE STAINED BY NORMAL STAINS?
• Due to presence of mycolic acids and cross linked fatty
acids and other lipids in the cell wall of organisms
,making it impermeable to usual stain.
M.tuberculi in Acid fast staining
Takes up satin by carbol fuschin.
Resists decolorisation by acids and alcohol.
Don’t acquire 20 stain methylene blue
These retain carbol fuschin hence they
appear red.

6. WHY TB AFFECTS ONLY LUNGS ?
M.tuberculi
Enters
Host cell
Utilizes
Cholesterol in cell membrane (Highly oxygenases amount involved in
metabolism of cholesterol into)
e-
• The concentrations of oxygenases greater in alveoli of
lungs .Hence Mycobacterium species majorly reside in
alveoli of lungs.
• And as it is strict aerobe strictly thrives best in tissues
with high Oxygen tension such as in the apex
of the lung
ATP

7. transmission
• TB is spread through the air from one person to
another via
– Inhalation( cough droplets)
– Ingestion (self-swallowing of infected
sputum),
– Inoculation(organisms into tissue which may
occur from infected postmortem tissue),
– Trans placental routes( Leads to congenital
TB).
types of tuberculosis
• Based on anatomical site
– PULMONARY TB (lungs)
– MILIARY TB (Liver, kidney spleen brain)

8. • Based on presence of signs and symptoms
– Active TB (only shows signs and symptoms).
– Latent TB (signs and symptoms are
absent-DORMANT).
• Based on type of tissue response and age
– Primary TB or Ghon’s complex or childhood TB
( infection of an individual who has not been
previously infected or immunised)
– Secondary TB or Post-primary or Reinfection,
or Chronic TB(infection of an individual has
been previously infected or sensitized).

9. Pathogenesis
• When ever the Mycobacterium tuberculi enters body. As it is
strictly aerobic it resides in alveoli of lungs.
• In alveoli, they will be engulfed by alveolar macrophages and with in
macrophages they will be converted into phagosome
• Phagosome should convert into phagolysosome but the M.tuberculi inhibits
the fusion of phagosome with lysosome there by no formation of
phagolysosome.
• Thus the mycobacterium tuberculosis antigen becomes “Difficut to
undergo Degradation”.

10. However, a very few no.of macrophages/some cells can process the
mycobacterial tuberculosis
The APC containing expressed MTB antigen enters lymphatic system and
reaches lymphatic organs.
CLONAL SELECTION
Activation of TH1cells(Cell mediated Immunity)
IL-1
INF-γ
TNF-α
Activation of INF-γ on endothelial cells of blood vessels
TH1
cell

11. Activation of Monocyte Adherent Protein (MAP) on endothelium and adherence
of monocyte to MAP
Squeezing of monocytes from blood to site of injury. Thus monocytes
entered into site of injury becomes Macrophages and increases in number.
Macrophages engulf Mycobacterium tuberculosis at site of injury.Due to
inhibition of Fusion of Phagolysosome, Macrophages are unable to digest
Mycobacterium tuberculosis

12. Granuloma (Agroup of cluster of epitheloid cells surrounded by rim of
lymphocytes around them)
IN GRANULOMA
Some of macrophages form Multinucleated giant cells by fusion of adjacent
cells (Langhans type)
Surrounding the epithelioid cells and giant cells there is a zone of
lymphocytes,plasma cells, and fibroblasts. This lesion at this stage is called
Hard tubercle due to absence of central necrosis.

13. Within 10-14 days, the centre of the cellular mass undergoes into
CASEATION NECROSIS(microscopically necrosis is structureless esinophilic
and granular material with debris) . This stage is called soft tubercle.
Wide spread of Soft tubercle over various parts of alveoli and lungs causes
PULMONARY TB.
These soft tubercle wide spread into various parts of the body like kidney
spleen, liver and bones etc.,.
In those freshly infected parts Mycobacterium tuberculi diffuse out of Soft
tubercle and infects which leads to formation of new granulomas.
Newly formed granulomas damages tissue and degenerates tissue surrounding
Extensive spread and damage of various parts of body occurs. This condition is
called MILIARY TUBERCULOSIS.

14. When infected person coughs or sneezes, the granulomas that may be present
in sputum comes in contact with air.
Lymphocytes, fibroblasts surrounding the cluster of epitheloid cells become
inactivated. And Mycobacterium tuberculi gets free from epitheloid cells
Comes in contact with another person
New person develops TB

15. SIGNS AND SYMPTOMS OF TB

17. INVESTIGATIONS
• Chest X- ray
• Laboratory diagnosis
– Sputum examination for AFB
– Complete haemogram (lymphocytosis and raised ERR).
– Culture and drug sensitivity tests using BACTEC radiometric method (
this method used to detect live bacilli) .
– D.N.A probe technology
– Nucleic acid amplification test- PCR
– ELISA testing for IgG antibodies ( It denotes only past infection , but
not useful as diagnostic aid).
– Drug susceptibility testing to anti-TB drugs.
– Gene Xpert (to differentiate 10 /Multi drug resistant TB)
– Fine needle aspiration cytology of an enlarged peripherallymph node is
quite helpful for confirmation of diagnosis
– INF- ɣTESTS
• T.SPOT
• Quantiferon TB gold intube
• Sputum collection
• Tuberculin test

18. • A presumptive diagnosis is commonly based on
the finding of AFB on microscopic examination
of a clinical sample (e.g., sputum/pus).
• When this is not possible, a probable diagnosis
may be made using imaging (X-ray/scans) and/or
a tuberculin skin test (Mantoux test).
• Tuberculin skin test, which yields a delayed
hypersensitivity type response (a small, raised,
blanched wheal) to an extract made from M.
tuberculosis (purified protein derivative; PPD).
• TUBERCULIN SKIN TEST: Purified protein
derivative (PPD), 0.1ml Intradermally, conc.
0.002mg/ml. If a raised bump of more than 5
mm (0.2 in) appears at the site 48 hours later,
the test may be positive.

19. •This test can often indicate disease when there is
none (false positive). Also, it can show no disease
when you may in fact have TB (false negative).
Interpretation
• 0–4 mm Negative
• 5–9 mm Doubtful (may be due to atypica
mycobacteria)
• 10 mm or more Positive
• In HIV infected individuals, 5 mm is considered
positive.
• Tuberculin negative patients should be
vaccinated with BCG.
• False-negative tuberculin tests (i.e. negative skin
tests occurring in patients with tuberculosis).

20. 20
Fig: Tuberculin test
Fig: Chest X-ray radiography
Showing cavity
Wheal

21. Complications

22. Prevention of TB
22
• Prevention strategies include BCG vaccination
and treatment of persons with latent
tuberculosis infection who are at high risk of
developing active disease.
• BCG was derived from an attenuated strain of M.
bovis.
• Efficacy is between 0-80%.
• BCG vaccine is recommended for routine use at
birth in countries with high tuberculosis
prevalence.
• Bacillus Calmette-Guérin (BCG)

23. ANTITUBERCULA
R DRUGS
FIRST LINE AGENTS
ISONIAZID(H)
RIFAMPICIN®
PYRAZINAMIDE
ETHAMBUTOL(E)
STREPTOMYCIN(S)
SECOND LINE
AGENTS
THIOCETAZONE(T)
PARAAMINOSALICYLIC
ACID(PAS)
ETHIONAMIDE(ET)
CYCLOSERINE(C)
AMIKACIN(A)
KANAMYCIN AND
CAPREOMYCIN (K)
NEWER DRUGS
(FLUOROQUINOLON
E MACROLIDE
ANTIBIOTICS,LINE
ZOLID,RIFAPENTIN,
RIFABUTIN)

25. ISONIAZID
Isonicotinicacid hydrazide
Catalase peroxidase (enzyme of
mycobacterium) activates
Aducts with
NAD NADP
InH a Kas a dihydrofolate
reductase
Inhibition of Inhibition of
Mycolic acid DNA synthesis
Bactericidal action
• Resistance :
– Mycobacteria may develops
resistance towards H due to
change in genes coding for
catalase peroxidase.
– Alteration in Kas a and Inh a
and in structure of efflux
pumps of bacteria.
• Pharmacokinetics:
– Orally well absorbed
– Well distributed
– Metabolized in Liver by
– Based on acylation
• Slow acetylators (Half
life- 3h)
• Fast acetylators( Half
life-1h)
– Excreted through urine
• Adverse effects:
– GI disturbances,
– Hepatotoxicity
– Peripheral Neuritis
– Hypersensitivity reactions

26. Mechanism of action
Rifampicin
Binds with Beta subunit of
DNA dependent RNA
polymerase
Inhibition of m.R.N.A
synthesis
Tuberculocidal effect
• PHARMACOKINETICS:
– Orally well absorbed
– High protein bound
– Distributed to all parts
– Metabolized in liver into desacetyl
rifampicin which undergoes entero-
hepatic circulation.
– Excreted largely in feces and small in
urine.
– Enzyme inducer for
• HIV protease inhibitors
• NNRTI’s
• Azole antifungals,Sulphonyl
ureas,Phenytoin, Warfarin,
Theophylline Carbamazepine.
• ADVERSE EFFECTS:
– Patients with hepatic disease are prone
to hepatitis
– Allergic reactions-Pruritis
– GI disturbances
– Flulike symptoms
RIFAMPICIN

27. PYRAZINAMIDE
MECHANISM OF ACTION
PYRAZINAMIDE
PYRAZINOIC ACID
mycolic acid synthesis Disrupts
inhibition cell
membrane
integrity
Tuberculocidal effect
• Pyrazinoic acid Highly effective in
acid environment and inflammatory
conditions
• PHARMACOKINETICS:
– Rapidly absorbed from GI tract
– It is widely distributed in the
body and achieves a concentration
in the CSF equal to the plasma
levels.
– Deaminated in theliver.
– Degradation products and he free
drug are eliminated in urine
• ADVERSE EFFECTS:
– Hyperuricemia (precipitating
gout)
– Metallic state
– Sulfurous eructation's
– Toxic hepatitis (Not dose related)
– Arthralgia,nausea,vomiting,anorex
ia,malaise,
– Rarely photosensitivity reaction
• Used in both Extrapulmonary and
pulmonary TB

28. ETHAMBUTOL
MECHANISM OF ACTION
Ethambutol
Inhibits Arabinosyl transferase
Inhibits Synthesis of ARABINO
GLYCANS
Inhibits cell wall synthesis
• Only tuberculostatic among all first line
Anti tubercular agents.
• Suppress the emergence of resistance
• Hastens sputum conversion
• PHARMACOKINETICS:
– 70% is absorbed
– Penetrates into erythrocytes, gets
deposited, and released into
circulation
– 50% of oral dose excreted
unchanged in urine with in 24h
– 15% excreted in the form of two
metabolites
– Accumulates in presence of renal
damage
• ADVERSE EFFECTS:
– Retrobulbular optic neuritis on
prolonged therapy which results in
decrease visual acuity.
– Others are
Nausea,headache,anorexia,allergic
reactions,and confusion
• If any visual disturbances are seen in
the patient,Ethambutol should be
removed from patient’s regimen

29. STREPTOMYCIN
MECHANISM OF ACTION
STREPTOMYCIN
Binds to 30S subuint of
ribosomes
Which results in production
Abnormal proteins
Accumulates in
mycobacterium
Destruction of
mycobacterium
• PHARMACOKINETICS:
– Not absorbed orally and must be
given in IM. Well absorbed when
instilled in intrapleurally
– It doesn’t cross BBB. However,
high concentrations are seen in
CSF during meningeal
inflammation.
– It is mainly concentrated in
kidneys, liver, and skeletal
tissues.
– It crosses Placental barrier,
– Excreted unchanged by GFR. And
approximately 50-60% of drug is
eliminated in urine in active form
within 24h.
• ADVERSE EFFECTS:
– Pain at the site of injection
– 8th cranial nerve damage
– Neuromuscular blockade
– Nephrotoxicity and ototoxicity
– Super infections with
Staphylococcus aureus and
candida

30. THIACETAZONE
• Because of its low cost and
efficacy combination with H it
was once used in 1st line drugs
for TB.
• It is orally active , rapidly
diffuses into various body
tissues ,Partly metabolized in
liver and about 40% excreted
unchanged in urine with t1/2 12h.
• It is no longer used now because
of its Exfoliative dermatitis
Stevens-Jhonson syndrome
ototoxicity and life-threatening
hypersensitivity reactions
(Hepatitis, neutropenia,
thrombocytopenia).
PARA-AMINO SALICYLIC ACID(PAS)
• It is chemically as well as in
mechanism of action related to
Sulfonamides.It is not active against
other bacteria and the reason may be
due to the difference in the affinity
of folate synthetase of TB and other
bacteria.
• Absorbed completely by oral route
and distributed all over the body
except CSF,about 50% PAS is
aceylated and competes with
acetylation of H- Prolongs its
t1/2.Excreted rapidly by Glomerular
filtration and tubular secretion.
• Patient acceptibility is poor because
of frequent anorexia, nausea and
epigastric pain and other adverse
effects are blood dyscrasias, fever
rash, etc.,.
SECOND LINE AGENTS
These alternative drugs that are useful in cases of resistance to 1st line drugs

31. CYCLOSERINE
• MECHANISM OF ACTION :It is
D-alanine analogue and hence it
replaces alanine which is essential
for cell wall synthesis.
• PHARMACOKINETICS: Rapidly
absorbed from gut,distributed
through out the body (csf and
plasma concentrations are equal in
meningitis condition).50% of orally
administered dose gets excreted
in urine in unchanged form and
65% is excreted by kidneys within
72h.
• Broad spectrum antibiotic and it is
tuberculostatic.
• It is effective against tubercle
bacilli resistant to H or S and
against atypical mycobacterium.
• ADVERSE EFFECTS:
– Peripheral neuropathy,
– Ataxia
– Delusions, Nervousnessetc.,.
ethionamide
• MECHANISM OF ACTION:
Blocks the synthesis of
mycolic acids and it is a
tuberculostatic drug.
• PHARMACOKINETICS:
ABSORPTION is similar to H,
Metabolized in liver and only
1% excreted unchanged in
urine
• Because of its Intense gastric
irritation and neurological
toxicity(optic and peripheral
neuritis) and hepatotoxicity, it
is rarely used, as in
recommended dose of 1mg/kg.
• ADVERSE EFFECTS:
• Purpura,
• GI disturbances
• Toxic hepatitis
• Miscellaneous:
Gynecomastia,
Mennorhagia etc.,.

32. Fluoroquinolones(CIPROFLOXACIN
and OFLOXACIN):
• The fluoroquinolones are useful
new addition to the anti
tubercular drugs.
Ciprofloxacin,Ofloxacin and
sparfloxacin are active against
M.tuberculosis as well as
M.avium complex.
• They penetrate cells and kill
mycobacteria lodged in
macrophages also.
• Because of their good
tolerability,they are being
increasingly included
combination regimens against
MDR TB and MAC infection
HIV patients.
• The generally employed doses
are ciprofloxacin 1500 mg/ day
and ofloxacin 800mg/ day in 2
divided doses. Sparfloxacin is
more active against
mycobacteria in vitro, but has
been used clinically to a lesser
extent.
Macrolide antibiotics
(CLARITHROMYCIN AND
AZITHROMYCN:
• These newer macrolide
antibiotics are most active
against nontubercular
mycobacteria including MAC,
M. fortuitum, M. Kansasii
and M. marinum.
• Clarithromycin has been
used to a greater extent
because its MIC values are
lower, but azithromycin may
be equally efficacious due to
its higher tissue and
intracellular levels.
• combination with other
drugs. In AIDS patients,
life-long therapy is
required-may cause
ototoxicity
NEWER DRUGS

33. MANAGEMENT OF TB
• Aims:
1. To kill the dividing bacteria in the lung lesions.
2. To kill the persisters so as to avoid relapse and ensure total cure
3. To prevent emergence of drug resistance
And based on
treatment is given
PATIENT
NEWLY
AFFECTED
PATIENTS
ACTIVE TB LATENT TB
PREVIOUSLY TREATED
PATIENTS AND BASED ON
DRUG SENSITIVITY TEST
LESS SENSITIVE
MORE
SENSITIVE

35. FOR NEWLY INFECTED PATIENTS
FOR PREVIOUSLY TREATED PATIENTS WITH LOW
RESISTANCE TO DRUGS
INTENSIVE PHASE
(2months)
H,R,Z,E+VitB6
CONTINUOUS
PHASE
(4months)
H,R+VIT B6
INTENSIVE PHASE
(3months)
HRZES HRZE
+
Pyridoxine 100mg/day
CONTINUOUS PHASE
(5months)
HRZ + Pyridoxine
100mg/day

36. MULTI DRUG RESISTANT OR HIGHLY
RESISTANT
INTENSIVE PHASE
(6months)
Z
E
AMIKACIN/KANAMYCI
N
OFLOXACIN/LEVOFLO
XACIN
CYCLOSERINE
ETHIONAMIDE+
PYRIDOXINE
CONTINUOUS PHASE
(12-18months)
E
OFLOXACIN/LEVOFLOXA
CIN
CYCLOSERINE
ETHIONAMIDE+
PYRIDOXINE
For H resistance: R+Z+E for 12Months
For R resistance: H+Z+E for 12Months
For both H+R resistance: Z+E+S(Et)+CIROFLOXACIN(OR OFLOXACIB
OR LEVOFLOXACIN),for 12-18 Months

37. DOT’s REGIMEN OF RNTCP(REVISED NATIONAL TUBERCULOSIS
CONTROL PROGRAMME) -1997

38. TB in special population
• TUBERCULOSIS IN PREGNANT WOMEN:
• H, R and Z to be safe to the foetus and
recommend the standard 6 month (2HRZ
+ 4HR) regimen for pregnant women with
TB. E can be added during late but not
early pregnancy. S is contraindicated.
• India, it is advised to avoid Z, and to
treat pregnant TB patients with 2 HRE +
7HR (total 9 months). Treatment of TB
should not be withheld or delayed
because of pregnancy.
• TREATMENT OF BREASTFEEDING WOMEN :
• All antiTB drugs are compatible with
breastfeeding; full course should be
given to the mother, but the baby
should be watched. The infant should
receive BCG vaccination and isoniazid
prophylaxis.
• In case of M. tuberculosis infection, drugs used are the same as in non-HIV cases,
but the duration is longer and at least 4 drugs are used.
• Initial therapy with 2 month HRZE is started immediately on the diagnosis of TB,
and is followed by a continuation phase of HR for 7 months (total 9 months).
• Alternatively, 3 drugs (HRE) are given for 4 months in the continuation phase.
Pyridoxine 25-50 mg/ day is routinely given along with H to counteract its
neurological side effects, which are more likely in AIDS patients.
• MDR-TB in HIV-AIDS patients should be treated for a total of 18-24
months or for 12 months after sputum smear negativity.
Tb in hiv

39. Treatment of TB in MAC
• Mycobacterium avium complex (MAC) infection is common in
HIV-AIDS patients, particularly when the CD4 count drops to <
100 cells/J.IL
• Clarithromycin/ azithromycin are the most active drugs against
MAC. A favoured regimen consists of an intensive phase of at
least 4 drugsclarithromycin/ azithromycin + ethambutol
rifabutin + one FQ / clofazimine/ ethionamide given for 2-6
months (duration is response based) .
• Followed by 2 drug maintenance phase with clarithromycin/
azithromycin + ethambutol/ one FQ/ rifabutin for at least 1 2
months or eYen lifelong.
• However, any additional benefit of the initial 4 drug intensive
phase is unproven. Clarithromycin inhibits the metabolism of
rifabutin.