Drug Therapy Of TB & Cough

Question 1

GR: resistance to TB develops readily

Answer 1

As the organisms grow slowly

Question 2

Mention the solution to poor compliance to TB medication

Answer 2

Directly obeserved therapy

Question 3

Mention 1st line anti-TB drugs

Answer 3

Rifamycins, isoniazid, pyrazinamide and ethamutol

Question 4

Mentiom treatment of LTBI

Answer 4

Isoniazid for 9 months

OR INH & rifapentine for 12 weeks

Question 5

Desribe initial phase of TB treatment

Answer 5

2 months of the 4 1st line drugs

Question 6

Describe the continuation phase of TB treatment

Answer 6

4 months of INH and rifampicin

Question 7

Time for treatment of extrapulmonary TB or with HIV coinfection

Answer 7

2 yrs

Question 8

Mention steps of TB patient monitoring

Answer 8

Clinical evaluation & culture (monthly)

Watching for drug side effects

Question 9

Mecahnism of action of isoniazid

Answer 9

Enzyme responsible for synthesis of mycolic acid acts on intracellular and extracellular organisms

Question 10

How does resistance of INH develop?

Answer 10

By overexpression of target enzyme, cross resistance with ethionamide

Question 11

Describe metabolism of INH

Answer 11

By acetylation in the liver, thus its T1/2 differs between slow and rapid acetylators.

Question 12

Describe adverse effects of INH

Answer 12

1. Hepatitis
2. Hypersensitivity
3. Peripheral and optic neuritis, memory impairment and convulsions. Pyridoxine phosphokinase inhibition, GABA is not synthesized, thus, CNS overstimulation occurs.
4. Enzyme inhibition

Question 13

Mechanism of action of rifampicin & resistance

Answer 13

Inhibit DNA-dependent RNA-polymerase

Mutations leading to decreased affinity of target enzyme to drug

Question 14

Mycobacterial spectrum of rifampicin

Answer 14

Acts intra and extracellularly and on necrotic tissue

Also acts on atypical mycobacteria and M.leprae

Question 15

Describe the absorption and distribution of rifampicin

Answer 15

Well absorbed after oral administration
Widely distrubted and destroys bacilli in macropahges
Crosses BBB

Question 16

Describe metabolism and elimination of rifampicin

Answer 16

Metabolized in liver, excreted in bile (mainly, enterohepatic circulation) and urine.

Question 17

Describe adverse effects of rifampicin

Answer 17

1. Skin rash, fever, GIT upset
2. Liver damage
3. Enzyme induction
4. Flu like symptoms
5. Red discoloration of secretions
6. Resistance

Question 18

Mention drug preferred to rifampicin in HIV patient and why?

Answer 18

Rifabutin

Less drug interaction

Question 19

Mention drug preferred to rifampicin in LTBI and why?

Answer 19

Refapitine

Longer half-life

Question 20

Describe mechanism and reach of pyrazinamide

Answer 20

Targets mycobacterial fatty acid synthase-1 gene involved in mycolic acid synthesis
Intracellular bacilli

Question 21

Adverse effects of pyrazinamide

Answer 21

Hepatitis, hyperuricemia, arthralgia and GIT upset

Question 22

Mention 1st line drug which is bacteriostatic

Answer 22

Ethambutol

Question 23

Mechanism of ethambutol

Answer 23

Inhibit RNA synthesis, distributed in the body and cross BBB

Question 24

Side effects of ethambutol

Answer 24

Optic neuritis, red/green colour blindness, decrease visual acuity, decrease uric acid excretion.

Question 25

Mechanism of action and side effect of dextromethorphan

Answer 25

M, sigma-1 opioid receptor agonist and noncompetitive NMDA antagonist so act on cough center in CNS
S, hallucinations

Question 26

Mechanism of action and side effect of pholcodine

Answer 26

M, direct depression of cough center in medulla

S, sputum retention

Question 27

Mechanism of action and side effect of antihistaminics as antitussive

Answer 27

M, H1 receptor antagonist suppress central cough mechanism

S, anticholinergic effects

Question 28

GR: dextromethorphan is preferred to codiene

Answer 28

Less dependence, conatipation and respiratory center depression.

Question 29

Mention peripheral antitussive and its mechanism and its side effects

Answer 29

Menthol
Aromatic substance - Demulcent effect (antitussive) and opens airway to reduce cough and congestion (expectorant)
Seizure, coma and death

Question 30

Indication of antitussive drugs

Answer 30

Dry unproductive cough

Question 31

Mechanism of action and side effect of acetylcysteine

Answer 31

M, Break disulphide bond of thick mucus

S, agiodema, pruritis and peripheral edema

Question 32

Mechanism of action and side effect of bromhexine

Answer 32

M, disrupts acid mucopolysaccharide making mucoid sputum less viscous to be easilty expectorated.
S, pain in upper stomach

Question 33

Mechanism of action and side effect of ambroxol

Answer 33

M, break down mucopolysaccharide making sputum thin to promote clearance.
S, difficulty in breathing and allergic reaction

Question 34

Uses of mucopolysaccharides

Answer 34

Productive cough, COPD, asthmatic bronchotis, cystic fibrosis, bronchiectasis, care of tracheostomy. Acetycysteine for paracetamol poisoning.

Question 35

Mechanism of action and side effect of guaphenesin

Answer 35

M, increase volume and viscosity of secretion allowing ciliray clearance
S, dizziness, headache, stomach pain

Question 36

Uses of expectorants

Answer 36

Productive cough

Question 37

Cough medicine CI in children

Answer 37

Central antitussives, guaiphenesin, pseudoephedrine, phenyleptherine.