Antimycobacterials

Question 1

Isoniazid ADR

1st line

Answer 1

ADRs - peripheral neuritis caused by a relative pyridoxine deficiency (B6) so must give INH w/ B6 50mg, life threatening hepatits
-specific for TB

Question 2

Rifampin ADR

1st line

Answer 2

ADRs-harmless red, reddish brown or orange color to urine, sweat, tears,saliva and onto contact lenses

• Cytochrome P450 enzyme inducer!!
• also used for leprosy when combined w/dapsone

Question 3

Pyrazinamide

1st line

Answer 3

ADRs - hyperuricemia, hepatotoxicity

Question 4

Ethambutol

1st line

Answer 4

dose related retrobulbar neuritis (loss of central vision and color discrimination

Question 5

Rifapentine

1st line

Answer 5

CYP450 enzyme inducer.

similar to rifampin

Question 6

Rifabutin

1st line

Answer 6

• not FDA approved for TB tx

- used as a sub for rifampin

Question 7

combo first line agents

Answer 7

Rifamate: Contains INH/RIF
Rifater: Contains INH/PZA/RIF

Question 8

streptomycin

2nd line tx

Answer 8

• used when TB is refractory to other therapies or if it is life threatening (HIV, meningitis)
• nephrotoxic, ototoxic (MONITOR peaks/troughs).

Question 9

capreomycin
ethionamide
cycloserine
p-aminosalicylic acid (PAS)

2nd line tx

Answer 9

nephrotoxic, ototoxic
hepatic impairment,
CNS somnolence

Question 10

Bedaquiline MOA

2nd line tx

Answer 10

diarylquinoline antimycobacterial drug that inhibits mycobacterial ATP synthase that is essential for the generation of energy
-only use with 3 other drugs

Question 11

Common regimen for active TB

Answer 11

Initial phase: INH, RIF, PZA , EMB and B6 x 8 weeks
Continuation phase: INH, RIF and B6 for 18 weeks (Continuation phase may be extended in certain patients)
Children – same recommendations except avoid EMB

Question 12

Principles of treatment for drug-resistant TB

Answer 12

Don’t add a single new drug, try at least 3 previously unused agents to which there is reported susceptibility
Use at least one drug via the parenteral route
Provide hospital-based or direct-observed therapy (DOT) to assure adherence

Question 13

PPD positive

Answer 13

– all pts should be treated w/ INH 300 mg PO daily
Adults – 9 mos
isoniazid (INH) and rifapentine (RPT) administered weekly for 12 weeks as directly observed therapy (DOT) is equal alt
children – 9 mos

Question 14

rifabutin

Answer 14

Indications: MAC prophylaxis in HIV pts, Tx of MAC infx in combo with azithromycin, clarithromycin or ethambutol for 16 weeks, TB

ADRs - rash, GI (take w/ meals to reduce effects), neutropenia, yellow-brown urine, sweat, tears, contact lenses.

Question 15

clofazimine

Answer 15

Indications: MAC, leprosy, resistant TB

ADRs GI effects (N,V,D, anorexia), skin discoloration and discoloration of urine, sweat, tears (red-brown to black), increased LFTs, hepatitis

Question 16

dapsone

Answer 16

-used for leprosy
MOA: Sulfone, inhibit folic acid synthesis by M. leprae, bacteriostatic
ADRs: GI, peripheral neuropathy, optic neuritis, blurred vision, proteinuria, nephrotic syndrome, lupus erythematosus.

Question 17

Thalidomide

Answer 17

• used for leprosy

- ADRs – phocomelia (congenital abnl of the limbs)