Fluoroquinolones
MOA?
Inhibits bacterial topoisomerase (DNA gyrase)
MOA: Sulfamethoxazole
PABA analog ⇒ Inhibits dihydropterate synthase
PABA is the precursor molecule to folate
(PABA + Pteridine → → → Folate. The initial reaction only occurs in bacteria)
MOA: Metronidazole
Free radical metabolites ⇒ DNA damage
(∴ Bacteriocidal)
What are the two phases of treatment for tuberculosis?
(1) 4 drugs for 2 months
(2) 2 drugs for 4 months
MOA: Rifampin
Inhibits DNA-dependent-RNA polymerase
Name 2 classes of antibiotics which exhibit reduced potency when taken with divalent cations
(1) Flouroquinolones
(2) Tetracyclines
MOA: Trimethoprim
Inhibits dihydrofolate reductase
As a general rule, compare when you would use Metronidazole vs. Clindamycin
In the treatment of ANAEROBIC bacteria,
(1) Metronidazole: Below the diaphragm
(2) Clindamycin: Above the diaphragm
What drug regimen is most commonly used to treat active tuberculosis?
(1) Rifampin
(2) Isoniazid
(3) Pyrazinamide
(4) Ethambutol
When can Rifampin be used as a monotherapy?
PROPHYLAXIS for those exposed to:
(1) Neisseria meningitis
(2) Haemophilus influenzae
Adverse Effects (4) : Flouroquinolones
(1) Torsades (what else?)
(2) GI distress
(3) Tendon rupture
(4) Teratogen
(Teratogen ⇒ Abnormal cartilage development)
What type of infections is TMP-SMX first line for?
(1) UTI
(2) Prostatitis
(3) Nocardia
(4) Pneumocystis jirovecci
(Prophylaxis for Toxoplasma, NOT treatment, which would be: combination of pyrimethamine and sulfadiazine, supported by leucovorin (folinic acid))
what does metronidazole treat in the setting of clostridium difficile
pseudomembranous colitis
MOA: Isoniazid
Inhibits the synthesis of mycolic acid
Which drug can turn bodily fluids orange?
Rifampin
In what age group are Flouroquinolones contraindicated?
<10
CD4: TMP-SMX prophylaxis against Pneumocystis jirovecci and toxoplasmosis
<200
<100
Adverse Effect: Metronidazole
Disulfiram-like reaction
Resistance and adverse effects to isoniazid
Resistance:
Downregulation of Kat G (Kat G ≡ catalase-peroxidase)
AE:
(1) Vitamin B6 Excretion (Co-administer Vitamin B6 to prevent peripheral neuropathy)
(2) ⇒ Peripheral neuropathy
(3) Seizures
(4) Hepatotoxicity (liver acetylation, increased AST)
(5) Drug induced lupus
(6) Inhibits CYP450
(INH = Injury to Nerves and Hepatocytes)
MOA and AE: Ethambutol
Inhibits arabosyl transferase ⇒ inhibits carbohydrate polymerization
AE: OPTIC NEURITIS
Name 2 factors which increase the risk of Flouroquinolone-induced tendon rupture
(1) Old age
(2) Glucocorticoids
Adverse Effects - Renal, neonates, cutaneous, anemia, bleeding: TMP-SMX
renal:
(1) Type IV renal tubular acidosis
(2) Interstitial nephritis
neonates:
(1) Neural tube defects
(2) Kernicterus
(Note: TMP-SMX ⇒ Neural tube defects due to ↓ folate levels)
cutaneous:
(1) Atopic reaction
(2) Steven-Johnson syndrome
(3) Photosensitivity
anemia:
(1) Pancytopenia ⇒ ↓ RBCs
(2) ↓ Folate ⇒ Megaloblastic anemia
(3) ↓ GSH ⇒ Hemolytic anemia
bleeding:
There is an increase in free Warfarin concentrate due to:
(1) Inhibition of CYP450 system
(2) Displacement from albumin
Quadruple therapy for H. pylori?
bismuth, doxycycline, metronidazole, PPI
Which antimycobacterial agent is a potent inducer of CYP450?
rifampin
Which antimycobacterial agent may precipitate gout attacks?
Pyrazinamide