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Pharm for final > Folic acid inhibitor > Flashcards

Folic acid inhibitor Flashcards

1
Q

The 2 enzyme target for bacterial folate antagonists are

A 
Dihydropteroate synthetase (sulfonamides; competes with PABA)
Dihydrofolate reductase (trimethoprim)
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2
Q

structural analogs of PABA and competitively inhibit the enzyme dihydropteroate synthase

A

Sulfonamide drugs

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3
Q

bacteriostatic against gram (+) and gram (-) bacteria

A

Sulfonamides

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4
Q

What are the 3 groups of sulfonamides?

A

1) Oral absorbable: Sulfadiazine, Sulfisoxazole, Sulfamethoxazole ( + trimethoprim)
2) Oral nonabsorbable agents: Sulfasalazine
3) Topical agents: Sodium sulfacetamide (Sulamyd), Silver sulfadiazine (Silvadene)

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5
Q

Sulfadiazine

A

An oral absorbable sulfonamide.

Used for: UTI; nocardiosis, rheumatic fever; prophylaxis; toxoplasmosis; uncomplicated malaria

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6
Q

Sulfamethoxazole ( + trimethoprim)

A

An oral absorbable sulfonamide

Used for: URI; UTI; prophylaxis and tx of P. carinii

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7
Q

Sulfisoxazole

A

An oral absorbable sulfonamide
Used for: Otitis media; UTI; chloroquine-resistant malaria
drug resistant malaria and Toxoplasma gondii

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8
Q

Sulfasalazine

A

Oral nonabsorbable sulfonamide
Used for UC, enteritis
Delayed –release tablets used to treat RA
Anti-inflammatory properties due to cleavage of sulfasalazine to sulfapyridine and 5-aminosalicylate

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9
Q

Sodium sulfacetamide (Sulamyd)

A

Topical sulfonamide. Used in ophthalmic solution or ointment for bacterial conjunctivitis
Also used to treat chlamydia trachoma infections most common cause of preventable blindness worldwide

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10
Q

Silver sulfadiazine (Silvadene)

A

Topical sulfonamide. Topical for burn infection prophylaxis

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11
Q

Sulfonamides: distrubution

A

Distributed throughout body including CNS and fetus
Sulfamethoxazole is highly protein bound to albumin (if you have a drug that’s highly bound to albumin, may displace)
Protein binding drug interactions (narrow therapeutic index to these meds): Warfarin, phenytoin, sulfonylureas

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12
Q

Sulfonamides: Adverse Effects

A

N/V/D, HA, photosensitivity
Fever
Skin rashes- Mild to life threatening
Blood dyscrasias including hemolytic anemia
Numerous “itis’s” (nephritis, hepatitis, vasculitis)
Crystalluria

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13
Q

Competitive inhibitor of dihydrofolic acid reductase
converts dihydrofolic acid to tetrahydrofolic acid
The next step in purine synthesis
Resistance also common

A

Trimethoprim

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14
Q

Trimethoprim: adverse effects

A

1) GI

2) megaloblastic anemia, leukopenia, granulocytopenia reversed with folinic acid

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15
Q

Uses for trimethoprim

A

Can be used alone for community acquired UTI or for prophylaxis of UTI

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16
Q

Combination of Trimethoprim+sulfamethoxazole is bactericidal or -static?

A

Bactericidal.

whereas sulfamethoxazole on its own is -static

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17
Q

What is the only Only available IV sulfonamide antibiotic

A

Trimethoprim+sulfamethoxazole (Bactrim/Septra)

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18
Q

Uses for Trimethoprim+sulfamethoxazole (Bactrim/Septra)

A

Alternative agent for: Community acquired pneumonia, UTI and prostatitis, Acute otitis media (not first choice unless you have PCN allergy)
Treatment of pneumocystis carinii (HIV pts)
Bacterial diarrhea
Prophylaxis: UTI, PCP & Toxoplasma gondii in AIDS pts, Peritonitis prevention in pts with cirrhosis

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19
Q

Drug that Inhibits DNA processing by:

Inhibition of DNA topoisomerases

A

Quinolones (fluoroquinolones)

20
Q

Drugs that Inhibit DNA processing by: Inhibition of DNA-dependent RNA polymerase

A

Directly - rifampin

Indirectly - nitrofurantoin

21
Q

Name this drug based on action: Block bacterial DNA synthesis by inhibiting DNA topoisomerase IV and topoisomerase II (DNA gyrase)
Inhibit DNA supercoiling, transcription and repair

A

Quinolones

22
Q

Quinolones act against which bacteria?

A

Active against gram (+) and gram (-) bacteria

Activity against Topo IV accounts for gram (+) spectrum

23
Q

Primary target of quinolones differ according to what?

A 
according to organism.
Topo II primary, Topo IV secondary 
E.coli
Topo IV primary, Topo II secondary
Staphylococci, streptococci
24
Q

Spectrum of activity of quinolones

A

Originally developed for enhanced gram negative coverage
Campylobacter, Enterobacter, E. coli, H. influenzae, Klebsiella, Salmonella typhi, Shigella, Vibrio cholerae
Limited activity against gram positive organisms

25
Q

Ciprofloxacin (Cipro)

A

quinolone. Excellent gram negative coverage with only moderate gram positive activity

26
Q

Levofloxacin (Levaquin)

Moxifloxacin (Avelox)

A

quinolones. Excellent gram negative coverage with improved gram positive coverage

27
Q

Trovafloxacin (Trovan)

A

quinolone. Continued gram negative and gram positive coverage with enhanced anaerobic coverage (B. Fragilis)

28
Q

List quinolones

A

Ciprofloxacin (Cipro)
Levofloxacin (Levaquin)
Moxifloxacin (Avelox)
Trovafloxacin (Trovan)

29
Q

Atypical pneumonia organisms that quinolones work against

A

Chlamydia pneumoniae

Mycoplasma pneumoniae

30
Q

intracellular pathogens that quinolones work against

A

Legionella
Mycobacteria tuberculosis
Mycobacteria avium complex

31
Q

clinical uses of quinolones

A

UTI
Sinusitis
Mycobacterial infections
Bacterial diarrhea
Salmonella, shigella, vibrio, campylobacter, traveler’s diarrhea
Soft tissue, bone and joint infections
Decubitis, prosthetic joints, osteomyelitis
Gonococcal and chlamydial infections
Pneumonia (community- or hospital-acquired)
Post-exposure prophylaxis for anthrax = cipro
Tx inhalation anthrax infection = levofloxacin
Trovafloxacin FDA restricted to life- or limb-threatening infections
Severe hepatic toxicity

32
Q

Gatifloxacin, levofloxacin, lomefloxacin and ofloxacin eliminated by?

A

Renal excretion

33
Q

Trovafloxacin and moxifloxacin are excreted?

A

non-renally (bile)

34
Q

Drug interactions of quinolones

A

Antacids, sucralfate, iron, multivitamins
CYP interactions most common with ciprofloxacin
Methadone and theophylline levels increased
Severe, fatal hypoglycemia with concurrent use of glyburide (diabetic pts)

35
Q

Moxifloxacin (Avelox)

A

quinolone. Oral or IV; broad spectrum single daily dose; targets DNA gyrase instead of Topo IV in gram (+)

36
Q

Gemifloxacin (Factive)

A

quinolone. Approved to treat mild-moderte CAP due to multi-drug resistant Streptococcus pneumoniae

37
Q

Metronidazole (Flagyl): MOA

A

Bactericidal
Metabolized to an intermediate that inhibits bacterial DNA synthesis and degrades existing DNA.
Selectivity due to its toxic metabolite that is not produced in mammalian cells

38
Q

Metronidazole (Flagyl): spectrum of activity

A

Anaerobic and protozoan infections
Amebiasis; trichomoniasis; skin infections; CNS infections; intra-abdominal infections; systemic anaerobic infections; tx C. dif; bacterial vaginosis; H. pylori; acne rosacea

39
Q

Metronidazole (Flagyl): contraindications

A 
History of blood dyscrasias
History of alcoholism
Hepatic disease
CNS disorders
Visual changes
1st trimester of pregnancy- disrupts organ formation-fatal (Category B in 2nd and 3rd trimester)
40
Q

Metronidazole (Flagyl): Drug interactions

A

Warfarin –>increased INR (international normalized ratio—how long it takes blood to clot. Increasing this= more likely to bleed)
Cimetidine (p450 inhibitor)  increased metronidazole levels
Lithium toxicity (bipolar conditions)
ETOH disulfiram-like rxn (flushing, HA, N/V, sweating or tachycardia

41
Q

Metronidazole (Flagyl): ADRs

A 
Vertigo, HA, confusion, seizures
Edema
N/V/D, abdominal cramping, constipation
Darkened urine, polyuria, dysuria, 
Transient leukopenia, neutropenia (reversible)
42
Q

Nitrofurantoin (Macrodantin, Macrobid): MOA

A

Poorly defined; appears to require reduction for activity –> reactive forms damage DNA and interfere with RNA synthesis and DNA replication
Bacteriostatic-low conc.
Bactericidal-high
Spectrum: Gram (+) & Gram (-)

43
Q

Nitrofurantoin (Macrodantin, Macrobid): ADRs

A

GI: N/V
Interstitial pulmonary fibrosis with chronic use
Hemolysis in patients with G6PD deficiency
Aggranulocytosis, thrombocytopenia (reversible)
Peripheral neuropathies, HA, dizziness
Significant skin reactions w/allergies.

44
Q

Polymyxin B: MOA

A

Bactericidal
Interact w/phospholipids on the outer plasma cell membranes of gram (-) bacteria, disrupting their structure.
Disruption destroys bacteria’s osmotic barrier leading to lysis

45
Q

What bacteria does Polymyxin B work against?

A

Gram (-) bacteria

Pseudomonas aeruginosa

46
Q

Daptomycin (Cubicin): indications

A

Reserve. Used for multi-drug resistant gram (+) bacteria
Bactericidal disruption of plasma membrane function by acyl tail poking hole in membrane allowing depolarization doesn’t penetrate into cytopolasm

47
Q

Daptomycin (Cubicin): ADRs

A

reversible myopathy, GI (N/V/D)

Pharm for final (11 decks)

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