TB Flashcards
1
Q
Ethambutol HCL
Indications
A
- Tuberculosis, in combination with other drugs
2
Q
Ethambutol
MOA
A
- Ethambutol is bacteriostatic. It is effective against M.TB and M.Bovis
- Blocks arabinogalactan synthesis by inhibition of an arabinosyl transferase enzyme
- Mycolic acids accumulate in wall, cells become spherical and possibly more permeable to other agents
- Its effect on cell wall improves the efficiency of other anti-biotics (EG clarithromycin) which are usually ineffective on M.Tuberculosis
3
Q
Ethambutol
Warnings
A
- Contra-indicated
- Optic Neuritis
- Poor vision
- Cautioned in
- Elderly and Young children
- Patients who cann’t understand warnings about visual side-effects should, if possible, be given an alternative.
- In particular, ethambutol should be used with caution in children until they are atleast 5 yrs old and capable of reporting visual symptoms
4
Q
Ethambutol
Adverse effects
A
- Visual disturbances- Ocular toxicity is more common in excessive doses or if renal function is impaired. Early discontinuation of drug is almost always followed by improvement of eyesight
- Nerve disorders
- Hyperuricaemia
- Nephritis tubulointerstitial
5
Q
Ethambutol
Monitoring
A
- Peak concentrations (2-2.5hrs after dose) should be 2-6mg/L
- Trough should be 1mg/L
- Renal function should be checked before treatment
- Visual acuity should be tested by Snellen chart before treatment with ethambutol
6
Q
Rifampicin
Indications
A
- Brucellosis in combination with other anti-bacterials
- Legionnaires disease in combination with other anti-bacterials
- Serious staphylococcal infections in combination with other antibacterials
- Endocarditis in combination with other drugs
- TB
- Prevention of TB in patients who have had close contact
- Prevention of secondary care of haemophilus influenza type b disease
- Prevention of meningococcal meningitis
- Multibacillary leprosy in combo
7
Q
Rifampicin
MOA
A
- Rifampicin is an active bactericidial anti-TB drug which is particulalry active against the rapidly growing extracellular organisms and also has bactericidial activity intracellularly
- Rifampicin has activity against slow and intermittently growing TB
- Rifampicin inhibtis DNA-dependent RNA polymerase activity in cells
- Specifically, it interacts with bacterial RNA polymerase but does not inhibit mammalian enzymes
8
Q
Rifampicin
Warnings
A
- Contraindicated in
- Acute Porphyrias
- Jaundice
- Cautioned in
- Soft contact lenses- can cause discolouration
9
Q
Rifampicin
Adverse effects
A
- Blood disorder- Thrombocytopenia with or without purpea is common
- CNS- Headache, dizziness
- GI- N&V
- General disorders- Pyrexia, chills
- Increased LFTs
- Side-effects that mainly occur with intermittent therapy include influenza-like symptoms (with chills, fever, dizziness, bone pain), respiratory symptoms (including shortness of breath), collapse and shock, haemolytic anaemia, thrombocytopenic purpura, and acute renal failure.
10
Q
Rifampicin
Interactions
A
- Anything metabolised by CYP
- Anti-arrythmics- qunidine
- AED- phenytoin
- Antipsychotics
- Anticoagulants- warfarin
- Dig
- Immunosuppressive agents
11
Q
Rifampicin
Monitoring
A
- Renal function
- Hepatic function- LFTs, vomiting, jaundice
- FBC
12
Q
Pyrazinamide
Indications
A
- TB in combination with other drugs
13
Q
Pyrazinamide
MOA
A
- Pyrazinamide exhibits bacteriostatic activity only at slightly acidic pH (therefore only active when in the cell)
- The growth of tubercle bacilli within monocytes is completely inhibited by pyrazinamide at a conc of 12.5ug/mL
- It is thought that when these are used with isoniazide it becomes effective in irradicating TB
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14
Q
Pyrazinamide
Warnings
A
- Contraindicated in
- Acute attack of gout
- Cautioned in
- Diabetes
- Gout in adults- inhibits excretion of urates resulting in hyperuricaemia
15
Q
Pyrazinamide
Side effects
A
- A hepatic reaction is the most common side effect of ‘Zinamide’ and may occur at any time during therapy. This varies from a symptomless abnormality of hepatic cell function, detectable only by laboratory tests, through a mild syndrome of fever, anorexia, malaise, liver tenderness, hepatomegaly and spleenomegaly, to more serious reactions such as clinical jaundice, and rare cases of hepatic failure and death.
Other side effects-active gout, sideroblastic anaemia, arthralgias, anorexia, nausea and vomiting, flushing, dysuria, malaise, fever, rash, hypersensitivity reactions such as urticaria and pruritus, aggravation of peptic ulcer and occasionally photosensitivity.
