Antitubercular drugs

Name the anti-tubercular drugs:

[A]First line drugs:

1) Tab-INH(Isonicotinic acid hydrazide)-I.

2) Tab/cap.Rifampicin-R.

3) Tab.Pyrazinamide-P.

4) Tab.Ethambutol-E.

5) Inj.streptomycin-S.

6) Tab.Thiacetazone-T.

[B]Second line drugs:

1) Cycloserine.

2) Levofloxacin.

3) Ciprofloxacin.

4) Amikacin.

5) Capreomycin.

6) Para-amino salicylic acid(PAS).

7) Kenamycin.

8) Viomycin.

9) Ethonamide.

10) Prothinamide.

Difference between the first line & second line drugs:

First line drugs	Second line drugs
1.More potent. 2.Less toxic. 3.More TI. 4.Usual drugs.	1.Less potent. 2.More toxic. 3.Less TI. 4.Reserve drugs:given if first line drugs fail.

Treatment of pulmonary TB by 6 month regimen:

[A] Intensive phase(1st 2 month):Patient will come daily to take the drugs(DOTs)

[B] Continuation phase(Last 4 month):Patient will be given drugs for 30 days in each visit.Thrice daily.

Treatment of pulmonary TB 9 month regimen:

[A] Intensive phase(Ist 3 month):Patient will come daily to take the drugs(DOTs)

[B] Continuation phase(1st 3 month):Patient will come each alternative daily to take the drugs(DOTs)

Treatment of pulmonary TB 12 month regimen:

1.Twice week	Streptomycin Isoniazide Pyridoxine
2.Daily	Isoniazide Thiaceytazon

Mechanism of actions:

Rifampicin	Rifampicin binds to the bacterial DNA dependent RNA polymerase enzyme→Inhibits RNA synthesis→No protein synthesis→No growth & multiplication of bacteria→Rifampicin is bactericidal Human also has DNA dependent RNA polymerase enzyme but Rifampicin does not bind to that.
INH/Isoniazid	INZ inhibits synthesis of mycolic acids→No integrite of cell wall→Lysis of the cell. INZ is active against rapidly multiplying bacilli.Less active against slow multipliers.
Ethambutol	Ethambutol inhibit synthesis of Arabinoglycan(an essential component of mycobacterial cell wall). It enhaces the activity of Rifampicin that has to cross the cell wall primarily.
Pyrazinamide	The drug is active in acid . Drug→Enters the macrophages due to lipid solubility→Acidic environment in the macrophages→Kills the tubercle bacilli. *Thus the drug is active against the slow multiplying itracellular bacilli. which are unaffected by other drugs.

Indications:

Rifampicin	1.Pulmonary tuberculosis. 2.Leprosy. 3.Serious staphylococcal infection,such as osteomyelitis,prosthetic valve endocarditis. 4.To eliminate the meningococcal carrige & staphylococcal carrige. 5.As prophylaxis in contacts of children with haemophilus.
INH/Isoniazid	1.TB. 2.Prophylaxis of TB.
Etambutol	1.Pulmonary TB. 2.Tubercular meningitis.
Pyrazinamide	1.Pulmonary TB. 2.Tubercular meningitis(as the drug can achieve high level in CSF)

Adverse effects:

Rifampicin	1.Harmless orange/red coloration of body fluid,such as saliva,tear,urine, sweat etc. 2.Liver damage-cholestatic jaundice,hepatitis. 3.Flu-like syndrome-fever,chills,muscle pain,respiratory wheeze etc. 4.Haemolitic anaemia. 5.Rash. 6.Thrombocytopenia. 7.Nephrotoxicity(Acute tubular necrosis) 8.Induces hepatic microsomal enz.
INH/Isoniazid	1.Liver damage:it is more common in rapid acetylators. 2.Peripheral neuropathy:Burning sensation. 3.CNS toxicity:Restlessness,numbness,insomnia,muscle twiching,convulsion, unpleasent sensation,memory loss. 4.Gastro-intestinal irritation-nausea,vomiting,diarrhoea. 5.Blood dyscrasias. 6.Allergic reactions-Fever,rash,SLE.
Ethambutol	Retrobular neuritis-loss of visual acuity,color blindness(Red-green)
Pyrazinamide	1.Hepatotoxicity. 2.Hyperuricemia→Acute gouty arthritis reversible. 3.Nausea,vomiting,drug fever.

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