Pharm Antimycobacterial Drugs

Front 1

Question: The primary reason for the use of drug combinations in the treatment of tuberculosis is to?

Back 1

Delay or prevent the emergence of resistance.

Front 2

Question: ****A 21 year old woman from Southeast Asia has been staying with family members in california for the past 3 mo and is looking after her sister's preschool children during the day. Because she has difficulty with English, her sister escorts her to the hospital. She tells the staff that the PT is very tired for the past month, poor appetite, and lost weight. Two weeks ago, she had symptoms of the "flu", fever, and night sweats. The PT feels better lately, except for a cough with a greenish sputum, sometimes specked with blood. She has rales in the left upper lobe. WBC is 12,000/uL and hematocrit is 33%. CXY reveals infiltrate in left upper lobe with possible cavity. Gram-stained smear shows mixed flora with no dominance. Acid-fast stain reveals thin rods of pinkish hue. Pulmonary tuberculosis is diagnosis.

Back 2

*****

Front 3

Question: ***What is the most appropriate course of action?

Back 3

Hospitalize the PT and start treatment with 4 antimycobacterial drugs. This is because organisms infecting PTs form Southeast Asia are commonly INH resistant (due to acetylation for liver elimination) and coverage must be provided with 3 other antituberculosis drugs in addition to isoniazid.

Front 4

Question: ***When treatment is started, what drug regimen should be initiated?

Back 4

Isoniazid, rifampin, pyrazinamide, ethambutol. Streptomycin is usually reserved for use in severe forms of TB or for infections known to be resistant to first line drugs.

Front 5

Question: ***Which statement concerning the possible use of isonizid (INH) is true?

Back 5

She should take pyridoxine daily (due to peripheral neuropathy), low risk of hepatotoxicity, fast acetylators (native americans) may require higher doses; and flushing palpitations, sweating, dyspena may occur after ingestion of tyramine-containing (INH inhibits monoamine oxidase type A) foods.

Front 6

Question: ***On her release form the hospital, the PT is advised not to rely soley on oral contraceptives to avoid pregnancy because they may be less effective while she is being maintained on antimycobacterial drugs. The agent most likely to interfere with the action of oral contraceptives is?

Back 6

Rifampin, since it induces CYP-450: anticoagulants, ketoconazole, methadone, and steroids present in oral contraceptives.

Front 7

Question: The mechanism of high-level INH resistance of M tuberculosis is?

Back 7

Reduced expression of the katG gene, resulting in underproduction of mycobacterial catalase-peroxidase, an enzyme that bioactivates INH.

Front 8

Question: A PT with AIDS and a CD4 cell count of 100/uL has persistent fever and weight loss associated with invasive pulmonary disease that is due to M avium complex. Optimal management of this PT is to?

Back 8

Treat with clarithromycin, ethambutol, and rifabutin.

Front 9

Question: A PT with pulmonary tuberculosis resulting form an INH-susceptible strain of M tuberculosis (rate of INH resistance known is < 4%) has been treated with INH, rifampin, and pyrazinamide for a total of 2 months. If the pyrazinamide is stopped at this time, treatment should be continued with INH and rifampin for a further minimum time period of?

Back 9

4 months.

In pulmonary TB, treatment with INH, rifampin, and pyrazinamide should be continued for a total of 6 months, with pyrazinamide included for the first 2 months only. If pyrazinamide is not used during the first 2 months, INH and rifampin must be given for a total of 9 months.

Front 10

Question: A 10 year old boy has uncomplicated pulmonary tuberculosis. After initial hospitalization, he is now being treated at home with isoniazid, rifampin, and ethambutol. Which statement about this case is accurate?

Back 10

His mother, who takes care of him, should receive INH prophylaxis.

Front 11

Question: This drug has been used prophylactically in contacts of children with infection caused by Haemophilus influenzae type B. It is also prophylactic in meningococcal and staphylococcal carrier states. Although the drug eliminates a majority of meningococci from carriers, highly resistant strains may be selected out during treatment.

Back 11

Rifampin

Front 12

Question: Which statement about antitubercular drugs is accurate?

Back 12

Resistance to ethambutol involves mutations in the emb gene. It also inhibits arabinosyl tranferases. Ocular toxicity is dose dependent.

Front 13

Question: Once-weekly administration of which of the following antibiotics has prophylactic activity against bacteremia caused by M avium complex in AIDs PTs

Back 13

Azithromycin--3-4 day half life.

Front 14

Question: Risk factors for multi-drug-resistant tuberculosis include?

Back 14

History of treatment without rifampin; recent immigration from Asia and living in an area over 4% isoniazid resistance; recent immigration form Latin America; residence in regions where isoniazid resistance is known to exceed 4%.

Front 15

Which drug is most likely to cause loss of equilibrium and auditory damage?

Back 15

Amikacin. Ototoxicity is characteristic of aminoglycoside antibiotics.

Front 16

What are the major drugs used in tubercuolsis?

Back 16

RIPES: Rifampin, Isoniazid (INH), pyrazinamide, ethambutol, and streptomycin.

Front 17

What is the MOA of isoniazid?

Back 17

Inhibition mycolic acid, a characteristic component of mycobacterial cell wall. Resistance emerges if used alone.

Front 18

Although INH is one of the more important drugs for TB, what else is it good for in regards to TB?

Back 18

During latent infection including skin test converters, and for close contacts of PTs with active disease, INH is used as a sole drug.

Front 19

What is the side effects of INH?

Back 19

Hepatotoxicity, peripheral neuropathy; drug induced lupus; G6PD-deficient hemolytic anemia.

Note: pyridoxine or vitamin B6 is given to prevent peripheral neuropathy; INH increases excretion of B6

Front 20

What is the MOA of rifampin? Its SE?

Back 20

Its a bactericidal agent that inhibits DNA-dependent RNA polymerase.

harmless orange color to urine, sweat and tears; hepatitis; thrombocytopenia; induces liver CYP450, nephritis.

Front 21

What are the uses of rifampin?

Back 21

Active against mycobacteria, as well as certain gram-negative bacteria (prophylaxis for PTs with meningococcal meningitis and H. influenzae type B).

It is also used with other drugs to fight TB and leprosy.

Front 22

Rifampin does what to CYP-450?

Back 22

Induces, increasing metabolism of warfarin, oral contraceptives, prednisone, ketoconazole, digoxin, glyburide.

Front 23

What is the MOA of ethambutol?

Back 23

Inhibits arabinosyl transferases, a component of mycobacterial cell walls.

Front 24

What are the uses of ethambutol and its side effects?

Back 24

Used to treat M. tuberculosis infections.

Does dependent retrobulbar neuritis, resulting in decreased visual acuity, red-green color blindness, and retinal damage.

Front 25

What is pyrazinamide used for, and what is its side effects?

Back 25

Used with other drugs against M. tuberculosis.

Polyarthralgia, photosensitivity, hepatotoxicity; GI intolerance, fever, hyperuricemia (gout), maculopapular rash, porphyria. Avoid in pregnancy!

Front 26

What is streptomycin used for? Its SE?

Back 26

It is an aminoglycoside. It is used to treat TB, tulareia, meningitis, and miliary dissemination with other drugs.

SE: Nephrotoxicity, ototoxicity

Front 27

What is the DOC for leprosy and its MOA?

Back 27

Dapsone. It inhibits folic acid synthesis. Rifampin and clofazimine are also used.

Front 28

SE of dapsone?

Back 28

G6PD-deficient hemolytic anemia, methemoglobinemia, GI intolerance.

Front 29

Dapsone can be used as a prophylaxis against?

Back 29

P. carinii infection in HIV PTs

Front 30

M. avium complex (MAC) is a disseminated infection of what, and what are the drugs used to fight it and prophylaxis?

Back 30

AIDS, and clarithromycin or azithromycin with or without rifabutin is recommneded for prophylaxis in PTs with less 50/uL CD4 count. Ethambutol and rifabutin used with azithromycin or clarithromycin for treatment.

Front 31

PT presents with dyspnea, fever, productive cough, night sweats for 2 months with upper lobe consolidation on CXR and acid-fast bacilli. How do you treat active TB?

Back 31

6 month regimen with rifampin. 2 months with isoniazid, rifampin, ethambutol, and pyrazinamide. Followed by 4 months of isoniazid and rifampin.

PT still has cavitary pulmonary TB and sputum cultures after 2 months of treatment, than second phase of isonizid and rifampin for 4 - 7 months.

Front 32

How do you treat latent TB?

Back 32

THIS is important, must distinguish between active and latent. Latent TB, treat with INH for 9 months, otherwise, treating active TB with INH will develop resistance.

Adding in rifampin or by itself for a few months in the beginning is ok. Treatment must be 9 months.

Front 33

What is the main complication of TB treatment with INH and what must be monitor?

Back 33

Hepatoxicity and ALT and ASt

Front 34

Isoniazid, rifampin, and pyrazinamide all cause what?

Back 34

Hepatotoxicity! Monitor liver enzymes.

Front 35

Side effects of Rifampin?

Back 35

Think Red for Rifampin: Body fluids (urine, feces, saliva, sweat, tears, all are bright red-orange color.

Also, RNA, for DNA-dependent RNA polyermase inhibition of M. TB

Hepatitis (less than INH)

Front 36

What is rifabutin used for, and what is it similar to?

Back 36

It is similar to rifampin; therefore, similar side effects and induction of CYP-450. It is used to treat Mycobacterium avium-intracellulare.

Front 37

What is clofazimine used for, and its side effects?

Back 37

Binds to DNA as an anti-inflammatory drug used to treat leprosy reactions.

Since it is a red-colored compound, where it deposits on the skin conjunctiva, it colors these tissues red. Where there is leprosy lesions, it colors these tan or black.

Front 38

What is one of the uses of thalidomide?

Back 38

To treat anti-inflammatory erythema nodosum leprosum.

Front 39

What does an osteosarcoma look like on the skull?

Back 39

Well marginated bump (golfball to baseball size mass) on the animal's head. Proliferative well marginated lump.

Front 40

How do you treat Mycobacterium avium complex?

Back 40

Prophylaxis with CD4 less than 50: Clarithromycin or azithromycin with or without rifabutin.

MAC infections: combination of azithromycin or clarithromycin with ethambutol and rifabutin.