TB Drugs Flashcards
What four drugs are used for TB therapy?
Isonazid, Rifampin, Pyrazinamide, Ethambutol
RIPE
How does Isoniazid (INH) work?
It inhibits mycolic acid synthesis and inhibits catalase peroxidase
Isoniazid inhibits ___ peroxidase
Catalase
What would happen if you used isoniazid (INH) by itself during active TB?
The patient will acquire resistance! Don’t do this! The mutation that causes this resistance is usually through a mutation or deletion of the catalase peroxidase or it’s regulating genes.
What is an adverse effect of INH?
Hepatitis. This is why patients liver function has to be monitored when they are on INH.
Peripheral Neuropathy in people with B6 deficiencies.
A malnourished TB patient lacking B6 is given INH. What adverse effect do you expect to see?
How do you prevent this?
We expect to see peripheral neuropathy. This occurs in patients taking INH who are malnourished or lack B6.
If the patient is B6 deficient, you should give them pyridoxine (B6)
A malnourished TB patient lacking B8 is given INH. What should you do?
Give them INH PLUS pyridoxine (B6)
Along with INH, what is another “cornerstone” drug for treating TB?
Rifampin - It is bacteriocidal
It blocks DdRP
How does rifampin work?
It blocks DNA-dependent RNA Polymerase.
Should you give Rifampin as monotherapy?
No! It will cause the patient to become resistant.
What should you give Rifampin with?
With INH. This will prevent resistance.
What is the MOR of rifampin?
Mutation in RNA polymerase.
What can we use to treat active TB and also latent TB?
Rifampin (IV/PO)
What is Rifampin and INH metabolized by?
The liver
What is the major side effect of using Rifampin?
Orange colored urine and tears along with HEPATITIS.
____ drug is a big P450 activator, which means that it causes P450 to metabolize other medications quicker (example, birth control pills)
Rifampin
A young woman comes to your clinic and finds out she is pregnant. She has been taking her birth control pills as scheduled and does not understand what happened. You look on her medical record and find out that she has TB and has been on Rifampin. What happened?
Rifampin is a big P450 activator, which means that P450 metabolized her BCP much quicker.
A patient with TB is also on coumadin, a blood thinner. What TB drug should you avoid?
Rifampin. Because rifampin is a big P450 activator, P450 can metabolize coumadin much quicker.
_____ is also a first line treatment for TB, but it is not a “corner stone” TB drug. When do we use it?
Is it resistant?
How is it administered?
What are some side effects?
Pyrazinamide (PZA) is also a first line treatment for TB, but not a cornerstone TB drug like Rifampin and INH.
We only use it in the initial phase of treatment because it is very active against rapidly forming organism and very bacteriocidal. Where it has its trouble is mopping up everything at the end.
Resistance is very rare.
It is administered orally 1x a day
It’s main side effect is hepatitis. It also increases urate and causes Gout.
A person develops gout and hepatitis after taking a mystery TB drug. What did he take?
He took PZA (pyrazinamide)
Which TB drug is bacteriostatic?
How does this drug work?
Ethambutol. It is not a cornerstone TB drug like Rifampin and INH, but it is a first line TB drug like PZA.
Ethambutol works by inhibiting arabinosyl transferase, an enzyme necessary for cell wall synthesis.
___ is a TB drug that works by inhibiting arabinosyl transferase, an enzyme necessary for what?
Ethambutol works by inhibiting arabinosyl transferase, an enzyme necessary for cell wall synthesis.
How is ethambutol used? What is the main side effect?
It is a TB drug that is used in combination with INH, RIfampin and PZA in the early part of a TB infection (before you know the drugs susceptibility). C
Combination therapy reduce thes potential for resistance to occur.
Ethambutol can cause color vision loss.
A patient comes to you with TB. You need to start her on an Rx regimen. What do you do?
Use all four TB drugs (RIPE) for 2 months. Then check TB susceptibilities. If it is fully susceptible, then stop the ethambutol and PZA and continue INH and rifampin to continue 4 months-6 months.
Someone who has latent TB should be on therapy for ___ on ___
9 months with INH
