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Pharmacology > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

0
Q

What are the aminoglycosides and who are they effective against?

A

These are they mycins…gentamicin, tobramycin, neomycin, amikacin, streptomycin…NOT Erythromycin or Vancomycin

All given IV except for Neomycin which is topical in an ointment

Use against G- bacteremia or for UTI
Use with Vanco or PCN for bacterial endocarditis
Use for mycobacterial infections (TB…use IV streptomycin)

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1
Q

What are the targets of the Protein Syn Inhibitors

A

Target the bacterial ribosome only, leaving the euk ribosome unaffected

  • Aminoglycosides and Tetracyclines–>30S
  • Macrolides & Clindamycin, Chloremphenicol, Streptogrammins, Linezolid—>50S
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2
Q

What are the MOA of the aminoglycosides?

A

First they passively diffuse down the porin channel (remember they are for G- and they have the porins)

Then they have ACTIVE O2 DEPENDENT transport across the cell membrane. (This is inhibited by anaerobic and acidic conditions…so anaerobes are innately resistant).

Their uptake is enhanced by a cell wall syn inhib like PCN or vanco.

Once inside it irreversibly binds the 30S P site and causes a frameshift in reading code—>Bactericidal

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3
Q

What are the pharmokinetics of Aminoglycosides?

A

They have minimal absorption so must be given IV (except who…?)

Dose is based on weight and creatinine clearance (renal function) and usually given 2-3x/day with normal renal function

Monitor patients that are receiving this for days at a time bc this can start to affect the kidney, or those whose renal function is changing or deteriorating

For high CNS penetration, use a intrathecal (injection directly into the spinal canal or intraventricular (delivery of drug to CNS within an implanted catheter or pump)

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4
Q

What is the mechanism behind once daily dosing of Aminoglycosides

A

It is based on concentration dependent killing (also true of floroquins)

  • As the amount of drug in the blood incr, so does the killing.
  • Has a post antibiotic effect where the aminoglyc continues to work even after the measurable levels of it are barely there. Prob bc it is taken up into the bact cell
  • TimeDependent Killing of Bacteria is characteristic of B lactams & Vanco
  • -Bugs are killed as long as the plasma conc is above MIC, therefore these drug’s levels need to always be above this level btwn doses
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5
Q

What are the pros and cons of once daily aminoglyc dosing?

A

Pro: Convenient for Outpatients, Less toxic
Con: Unproven in bacterial endocarditis, pregnancy, burn patients, severe renal impairment

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6
Q

What are the causes and risk factors of Aminoglyc nephrotoxicity?

A

These drugs can cause ACUTE renal injury indicative by a rise in plasma creatinine concentration.

-Since they are filtered across the glom then filtered in the prox tubule, its these tubules that are damaged. Fortunately the prox tubules can regenerate and this damage is reversible, and renal function can be recovered.

Risk Factors:
Prolonged Therapy, Frequency of Dosing
Advanced Age,
Comorbidities (diabetes, renal disease)
Concomitant meds (loop diuretics, vanco, amphotericin)
Elevated plasma drug concentrations
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7
Q

What is a way to avoid aminoglyc nephrotoxicity

A

Use once daily dosing bc renal cortical accumulation is way less with this method. Also, this method only requires a periodic TROUGH level

-If not, the serum peak and trough levels should be monitored closely.

Acute kidney injury can still occur either way

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8
Q

What is the irreversibly toxicity of Aminoglycs?

A

Ototoxicity.
It causes cochlear damage that may result in permanent hearing loss and damage to the vestibule as well (vertigo, ataxia, nystagmus)

Free radicals generated in the ear which damage sensory cells and neurons.

Gentamicin in particular damages hair cells so this is toxic to the vestibule only not cochlear. So GENTAMICIN WONT MAKE YOU DEAF, ONLY DIZZY OR OFF BALANCE

Audiometric testing used with aminogly use

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9
Q

What are the clinical uses for aminoglycs?

A

They are used for G- sepsis or bacteremias
Endocarditis with strep, enterococcus or staph
Often used in combo with other B lactams, esp for treating
-PSEUDOMONAS, LISTERIA, ENTEROCOCCUS

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10
Q

What kills Listeria?

A

Ampicillin with an Aminoglycoside

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11
Q

What is gentamicin used for?

A

Bugs:
Staph (only as a synergistic with PCN or vanco, not by itself) and G- (pseudomonas, Proteus, Enterobacter, Klebs, Serratia, Stenotrophomonas
-Has NO ANAEROBE activity (O2 dependent, remember?)
Only used for G+ as a synergistic or as a topical eye drop
-ie B lactams, vanco

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12
Q

What is Tobramycin used for?

A

Pseudomonas

Available as an inhaled solution for pseudomonas lung infections with CF patients

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13
Q

What is streptomycin used for?

A

First line IV treatment for TB

15% of gentamicin resistant enterococcus will be sensitive to streptomycin

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14
Q

What is amikacin used for?

A

Used for G- infection resistant to gentamicin and tobramycin
-bc amikacin is usu resistant to the group transferases that inactivate toby and geni

Treats mycobacterial infections (both atypical and resistant)

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15
Q

What is neomycin used for?

A

Used as a topical and bowel prep, and for hepatic encephalopathy

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16
Q

What is cefepime used for?

A

4th generation cephalo that does what 3rd gens do + have pseudomonas coverage. It also more resistant to lactamases

17
Q

What are the 4 tetracyclines and how are they administered?

A

1) Tetracycline - PO QID (4 x/day)
2) Doxycline - PO (100% bioavailable) or IV
3) Minocycline - PO 100% bioavailable
4) Tigecycline - IV

18
Q

How are the tetracycline eliminated?

A

Through the urine, others via biliary or fecal route

It goes thru enterohepatic circulation

19
Q

What is the spectrum, bugs/infections that tetracyclines work against?

A 
Spectrum:
G+, G-
Chlamydia and Mycoplasma
Rickettsia and Borellia (Lyme disease)
H. Pylori, Vibri, P Falciform

Common uses: MRSA, acne, atypical and community acquired pneumonia, chlamydia, Lyme Disease, Rocky Mountain Spotted Fever, H. Pylori, malaria prophylaxis

Use Demecyclocyline for SIADH which inhibits ADH in renal tubule…makes you pee it seems like

20
Q

What is Tigecycline and what is it used for?

A

It is a broad spectrum that covers:
MRSA, VRE, Anaerobes
-NOT pseudomonas, Proteus, Providencia, and Morganella

-Use for skin and abdominal infection

  • Has poor urine conc so DONT USE FOR UTI
  • HAS poor blood conc so DONT USE FOR BACTEREMIA
21
Q

What are the adverse effects of the tetracyclines?

A

Binds di and tri valent cations ie Ca2+ so dont take with food, esp dairy or vitamins.

In children will bind to the Ca in their teeth and turn them brown. So dont give to kids or pregnant women.

Also phototoxic

Irritates GI/Esophageal tract locally

22
Q

What is the MOA of Erythromycin and what is its spectrum?

A

It binds to the 50S subunit
It is given orally or topical

Spectrum:
G+ organisms (Pneumococci, Strep, Staph)
Mycoplasma, Legionella
Chlamydia, Pertussis

23
Q

What are the adverse effects of erythromycin?

A

GI Issues (n/v diarrhea) For this reason, it is used to treat motility disorders ie gastroparesis

Hepatoxicity (esp erythromycin estolate), and inhibitor of CYP450, increases theophylline, anticoagulants, cyclosporin

Increases digoxin level by increasing bioavailability

24
Q

What is clarithromycin and it’s spectrum?

A

PO
Broader than erythro; more active against G- (Haemophilus), MAC

Treats H. Pylori (with Ammox and Lansoprazole, a PPI)

Has drug interactions

25
Q

What is arithrymocyin and it’s spectrum

A

IV or PO

Like clari, but with less GI upset and drug interactions

Slightly more active against G- (H. Influenza)

Spectrum:
Chlamydia, MAC

Half life of 3 days so this lasts a long time. Can do a one gram dose for chlamydia, and 1200 mg 1x/wk for MAC

Zpak for Comm Acq Pneumonia

26
Q

What is Clindamycin and what is its MOA?

A

Cl substituted derivation of lincomycin

Binds to 50S ribosome just like erythromycin and prevents production of bacterial toxins

IV or PO or topical

Good Bone Penetration so use for osteomyelitis

27
Q

What is the Spectrum for Clindamycin

A

G+ (staph, strep, pneumococcus)
Anaerobes (Bacteroides, and some g+/- anaerobes)
Resistance to clindamycin usu means resistance to all macrolides
Dose is 600 mg PO/IV TID

28
Q

What kind of infections is clindamycin used for?

A

Skin and Soft tissue infections (Strep & MRSA)

Anaerobic Infections
-ie Aspiration Pneumonia (huge, remember this)
Abdominal Wounds
Gynocological (pelvic abscess, septic abortion, bacterial vaginosis)

29
Q

What are the adverse effects of clindamycin

A

-C. DIFF!!! This is the main thing it predisposes to but clears out normal flora. (Floroquinolones, broad spectrum PCNs and cephalos too)

30
Q

What is the MOA of chloremphanicol and what are its adverse effects?

A

It binds to 50S and prevents peptide bond formation

Cheap in dev world, not really used here bc it works like a cancer drug, but used overseas for typhoid fever and meningitis

Aplastic Anemia and Gray Baby Syndrome (where high doses accumulate bc baby’s liver dont have the necessary enzymes to break it down. Causes vomiting, flaccidity, hypothermia, and shock)

31
Q

What are the two streptogrammins? How are they used and what is the spectrum?

A

Quinupristin and Dalphopristin
They are used together in a 30:70 ratio mix of Q to D

Spectrum:
G+ Cocci (strep, staph (MRSA/MSSA, E. Faecium) FYI E. Faecium is enterococcus…wow now I remember

Used for VRE which is vanco resistant e. faecium or enterococcus

Can get infusion related toxicity so need a central line.

32
Q

What is Linezolid and what is its MOA?

A

It is a protein syn inhib that binds to the 23S of the 50S subunit.

NO CROSS RESISTANCE WITH OTHER DRUG CLASSES

600 mg BID Po or IV. 100% bioavail with oral

33
Q

What is the spectrum of Linezolid?

A

Used for G+ (MRSA, VRE)

Use for pneumonia and skin infections. Even PRSP

34
Q

What is another function of Linezolid in the brain in the role of NT metabolism?

What drug given with it will produce what NT disorder? What are the symptoms of this disorder?

What is a side effect that is seen after two weeks of administration

A

It is a weak MAO inhibitor, (enzyme that breaks down serotonin)

If given with SSRIs, it can cause a dangerously high level of 5-HT in the brain causing SEROTONIN SYNDROME.

- Symptoms: mental changes, muscle twitching, sweating, shivering, fever, diarrhea
- Also avoid cheese and red wine bc of the tyramine

Thrombocytopenia is seen after two weeks, also anemia and neutropenia

35
Q

What are the selected drugs used for Staph Aureus?

A

MSSA:
Naf/Dicloxacillin
Cefazolin/Cephalexin

MRSA:
Vanco
Daptomycin
Coxycycline/Tigecycline
Clindamycine
Linezolid
TMP/SMX
36
Q

What are the selected drugs for Enterococcus (E. Faecium)

A 
Enterococcus: (basically all the PCNs except for very narrow bc they only work on staph)
PCN
Ampicillin
Pipercillin
Vancomycin
VRE:
Daptomycin
Quino/Dalfo
Linezolid
Tigecycline
37
Q

What is Metronidazole and what is its MOA?

A

It is a bactericidal used for C. Diff

LMW that diffuses across cell membrane

Selective toxicity twd ANAEROBIC (clostridium) and microaerophilic bugs

- These bugs contain e- transport components that donate electrons to Metro.
- That single donated e- forms a highly reactive nitro radical anion that kills the bug resulting in DNA strand breakage.
38
Q

What are the adverse effects of Mitro?

A

Metallic taste in mouth
Disulfiram effect
N/V
Peripheral Neuropathy/seizures

39
Q

What is the pharmocology of Metro? What kind of activity does it have and against what bugs?

A

PO/IV/PR

Topical vaginal and facial
Metabolized in liver
500 mg IV/PO TID

Indications:
Antiprotozoal and antibacterial (anaerobic) activity
	-Bacteroids
	-Clostridium
	-Trichomonas
	-Giardia
	-Entamoeba
Can be used for:
Brain Abscess with Ceftriaxon, Roseaca, Bacterial Vaginosis (Flagil)

Pharmacology (17 decks)

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