Protein Synthesis Inhibitors Flashcards by Aliyah Thompson

Bactericidal protein synthesis.

Aminoglycosides

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2 names of aminoglycosides

Gentamicin &amikacin

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Bacteriostatic protein synthesis inhibitors

Tetracyclines, phenicols, lincosamides, macrolides

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Function of 30S subunit

Binds mRNA in initiation, holds peptide chain

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Function of 50S subunit

accepts/translocates charged tRNAs
A site: acceptor site
P site: donor site

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Bactericidal Drugs that target 30S

Tetracylines

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Bactericidal Drugs that target 50S

Phenicols, macrolides, clindamycin

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Bactericidal drugs that do irrversible binding to 30S

Aminoglycosides

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Types of aminoglycosides

drugs that end in “-micin” or “mycin”
neomycin (topical only)
kanamycin
gentamicin
amickicin
apramycin

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Name a natural & a semi-synthetic aminoglycoside

natural: gentamiccin
semi-synthetic: amikacin

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Spectrum of aminoglycosides

gram -ve aerobes (pseudomonas)
selected gram +ve aerobes (staphylococcus)

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Aminoglycosides must be used in combo with/ what abx in gram +ve aerobes

beta lactams (synergistic)

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T or F: aminoglycosides are 1st-2nd tier drugs & 3rd-4th tier in horses

False; they are 3rd-4th tier drugs & 1st-2nd tier in horses

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Solubility of aminoglycosides

water soluble
weak bases (ionize in acids)

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How to aminoglycosides get through cell membrane?

oxygen dependent
active transport
low efficacy in anaerobic environment

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Aminoglycosiides have inheent resistance to

Obligate anaerobes

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Which 2 ions repel aminoglycosides

calcium
magnesium

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Target MIC for aminoglycosides

10X

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What pH are aminoglycosides trapped in

Acidic
- milk
- kidney
- GI (lower oral absorption)

What pH enhances efficacy of aminoglycosides

Alkaline

Routes of admin for aminoglycosides

IM & SQ generally
can be given IV

Aminoglycosides are not very soluble in

Lipids

Poor distribution of aminoglycosides intracellularly in

CNS & eye

Aminoglycosides selectively bind to

Kidney tissue, cochlea, vestibular apparatus

Excretion of aminoglycosides

- mainly unchanged in urine unless give per os - can get trapped in acidic urine and accumulate in kidneys-> nephrotoxicity

How may times per day do you dose aminoglycosides

Real excretion

- 1-2 hr 1/2 life - clearance proportional to serum creatinine conc.

3 toxicities of aminoglycosides

- ototoxicity - nephrotoxicity - neurotoxicity

Neurologic aminoglycoside tox.

- neuromuscular tox - antagonized w/ neostigmine or calcium - interferes w/ calcium & ACh influx

Ototoxicity of aminoglycosides

- destroys sensory cells in cochlea and vestibular apparatus - progressive, can be irreversible - signs: ataxia, loss ofbalance, vertigo, hi freq. hearing loss

Rank gentamicin, amikacin, and neomycin by toxicity lvls from greatest to least

Neomycin, gentamicin, amikacin

Drugs that cause cochlear tox.

Amikacin, kanamycin, tobramycin

Drugs that cause vestibular tox

Streptomycin, gentamicin, tobramycin

Aminoglycoside extra label use

- discouraged - no official withdrawal times - approved drugs: apramycin in pigs & calves 28 day withdrawal

AmiNOglycoside rules

- no protein synth - gram -ve killer - no activity against anaerobes - nephro & ototoxic - no oral availability

How many tetracycline groups are there

General info abt tetracyclines

- broad spectrum (include protozoa) - relatively safe - freq. cross resistance - bacteriostatic (30S)

Group 1 tetracyclines

- older - short dose interval - natural - tetracycline, oxytetra., chlortetra.

Group 2 tetracyclines

- intermediate dose intervals - democlocycline, methacycline

Group 3 tetracyclines

- newer - longer dose intervals - synthetic - doxycycline, minocycline

MOA tetracyclines

Binds to 30S preventing aa-tRNA binding

Route of admin for tetracyclines

- PO (usually) - can be given topicaly& parenterally

Bioavailability for tetracyclines

- 90-100% for doxy; worse for groups 1 & 2 - absorption decreased by milk

Distribution of tetracyclines

- binds to Ca2+ (teeth discoloration) - wide distr. to body fluids and tissue (not CNS) - Minocycline & doxycycline=lipid soluble

Excretion