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35 Cards in this Set
- Front
- Back
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Describe the general Aminoglycosides –Structure, Use, Route
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Polar cations made of Amino sugars attached to amiocylitol ring by glycosidic link
Reserved mostly for serious G- & Used with B-lactams for synergistic effect/G+ coverage Parenteral use – IV usually |
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Mechanism of synergism of Aminoglycosides w/ B-lactams:
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Inhibiting cell wall synthesis (b-lactam) increases penetration of aminoglycosides
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SE of Amioglycosides
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Nephotoxic & Ototoxic, excreted by kidney so dose adjusted for renal function. OTOXIC in neonates = caution if pregnant, as accumulates fetal plasma
Can cause Neuromusclular block (resp paralysis) due to decrease Ach Release. |
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How do you Tx respitory paralysis as a side effect of Aminoglycosides?
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Need to correct the problem caused by decease in Ach release
Give IV Ca+ or neostigmine (cholinesterase inhibitor, allowing the Ach to act for longer period of time before degradation) |
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Mechanism of Aminoglycosides:
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Enter periplasmic space of G- through porin channels.
Pass Thru inner membrane by flowing down electrochemical gradient |
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How does the action of Aminoglycosides change with dosage?
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Static effects dependent upon concentration
-Low levels cause misreading of mRA faulty proteins -Higher levels inhibit initiation of transcription no proteins Cidal when faulty proteins (made during low dosage) insert into cell membrane, causing leaking ions & proteins |
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Where are the highest level of aminoglycosides attained?
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-Renal Cortex Nephrotoxicity
Reversible as tubular cells regenerate -Edolymph Ototoxicity Irreversible – sensory hairs don’t grow back Mech: Could disrupt ion flow or some other mech; unknown for sure Degeneration of auditory nerve permanent hearing loss |
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Name 3 aminoglycosides given by IV & their uses
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Genatmicin – topical for superficial eye infect, for burns & wounds, and to prevent catheter infec.
Tobramycin – same uses as gentamicin, sometimes combined with dexamethasone (anti-inflamm) for G- eye infect Amikacin – Nosocomial infections that resist gentamicin & tobramicin |
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Name 3 oral aminoglycosides and their uses
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Kanamycin – for prep for bowel surgery. Can also be used IV
Neomycin – for prep for bowel surgery & topical anti-infectant Paromomycin – DOC for amebic dysentery (protozoa Entamoeba histolytica) |
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What are the 2 ways to adjust dose for Renal Fcn?
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1) increase or decrease dose
2) change dosing interval |
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What is Creatinine clearance? Use? Units? What’s “normal” level?
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Time to clear creatinine from kidney, used to determine renal function
Expressed in ml/min – normal is 125 ml/min |
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What is the Cockcroft-Gault equations & what is it used for?
How is it altered for women? |
(140-age) x (lean wt in kg)
------------------------------ 72 x [Serum creatinine, mg/dl] – to estimate Creatinine clearance For women, multiply by 0.85 |
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How is Lean Body Weight (LBW) calculated?
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Male= 50 KG + 2.3 kg for each inch over 5 ft
Female = 45.5 + 2.3 kg for each inch over 5 ft |
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How do you determine the Aminoglycoside dose for a patient when taking Renal fcn into acct?
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Max daily dose x estimated Cl
----------------------------- 125 ml/min |
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What do the terms “desired peak level” and “trough” level refer to?
Are these levels the same for all the IV aminoglycoside? |
Peaks level is [drug] 30-60 min after dose, trough just before next dose
No, Amikacin has very different desired peak level than gent & tobra (don’t need to know specifics) |
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What is the general structure of Tetracylines? Use?
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4 rings
Broad spectrum 2nd line against G+ & G- |
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What is the Mech of Tetracyline?
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Inhibits binding of aminoacyl tRNA to acceptor site of ribosome - Static by preventing translation
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Name a short-acting Tertracycline. What is its “half-life”? Use?
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Short acting: T ½ = 6-8 hrs
Tetracycline (Rx) – Alternate oral or topical for inflammatory acne (1st DOC topical erythromycin + benzoyl peroxide) |
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Name an intermediate acting Tetracycline? What is its “half-life”? Use?
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Intermediate Acting: T ½ ~ 12 hrs)
Democlocyine – Used to treat chronic dilutional hyponatremia assoc with Syndrome of Inappropriate ADS secretion (water retetion) |
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Name a Long Acting Tetracyline? What is its “half-life”? Use?
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Long acting: T ½ = 16-18 hrs
Doxycycline – Oral & IV 1st DOC for Ricketsia (Rocky Mt Spot Fever), Chlamydia trachomatis, lyme disease. Alt for Syphilis c/ PCN allergy (Fluorquinolone DOC) |
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What stomach contents inhibit tetracycline absorbtion?
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Dairy products & antacids – causes chelations by the calcium or metallic salts
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What is the mechanism of Tetracyclines?
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??????? I missed this somehow??? Help?
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SE of Tetracylines:
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-GI upset
-Photosensitivity -Permanent brown discoloration of teeth |
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What is Tigecycline – drug or class? Mech? Use?
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Class similar to tetracyclines & might have similiar effects. Same mech of tetracyclines. Use: MRSA & tetracycline sensitive G-/G+, complicated skin & intra-abd infection
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Describe structure of Macrolides. Effective against?
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Large lactone ring w/ 1+ deoxy sugars.
All are effective against MSSA, Moraxella catahhralis, H. influenzae |
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Describe the Main Mech of Macrolides
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Inhibits translocation of tRNA from acceptor to donor site of ribosome, thus preventing protein translation
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Name 3 Macrolides
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Erythromycin
Azithromycin Clarithromycin |
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Erythomycin: Route? 5 Salt versions? Which salt best absorbed?
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Usually oral, EC = enteric coated free base
5 salt versions available: estolate, stearate, ethylsuccinate, lactobionate, gluceptate Best absorbed: Estolate salt, but can cholestatic hepatic |
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Erythromycin was the 1st Rx effective against what? How is it used now?
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1st vs Legionnaires’ – now Azithromycin or Levofloxacin are DOC & erythro is alternate
Erythro DOC for Pneumonia for Campy jejuni, Conyne diphtheria, Boredetella pertussis Erytho is a component of Pediazole for Otitis Media (along with sulfisoxazole) |
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What are the SE of Erythromycin?
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-Metabolites complex c/ cytochrome heme Fe & inhibit CYP3A, decreasing erythro metabolism
-Can prolong cardiac repolarization torsades arrhythmia. Incr risk if used with other Rxs that inhibit CYP3A (incr. erythro level) -Doubles risk of sudden cardiac death. Risk increases 5x with concurrent use of diltiazem or verapamil (CV drugs, anti-arrhythmic drug) |
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Azithromycin is in which class? Use?
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Macrolide used for community acquired pneumonia, legionnaires, Chlamydia trachomatics, Mycobac avium, & alt for Bordetella pertussis
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What is the “Half-life” of Azithromycin? Metabolism?
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T ½ = 70 hrs. Concentrates intracellularly. Doesn’t inhibit P450. Excreted unchanged in bile
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Use of Clarithromycin? SE?
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For comm. Acquired pneumonia & Mycobac avicum & is part of a “tx cocktail” forH. Pylori.
SE: Has caused low blood sugar & does inhibit CYP3A (incr Rx level) |
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Describe Ketolide
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New class – a macrolide derivative with incr G+ activity.
Mech same as macrolides |
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Name one Ketolide. Use? Concentrates where?
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Telithromycin used for comm. acquired resp infect. Active vs B-lactam & macrolide resistant bugs but some resistance is already forming. Concentrates in pul tissues & WBC.
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