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Chapter 82-92 Lehne Pharmocology
Used for studying pharmocologic effects of antibiotics.
88
Biology
Undergraduate 3
12/03/2009

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Term
What is Selective Toxicity?
Definition
Selective toxicity is defined as the ability of a drug to injure a target cell or target organism without injuring other cells or organisms that re in intimate contact with the target.
Term
What are the three ways that selective toxicity can be achieved?
Definition
Disruption of a bacterial cell wall, Inhibition of an enzyme unique to bacteria, disruption of bacterial protein synthesis.
Term
How can an organism develop tolerance to a drug?
Definition
Microbes may elaborate drug-metabolizing enzymes, microbes may cease active uptake of certain drugs, microbial drug receptors may undergo change resulting in decreased antibiotic binding and action and microbes may synthesize compounds that antagonize drug actions.
Term
What is a suprainfection?
Definition
A suprainfection is simply a special example of the emergence of drug resistance.  This happens when antibiotics kill off normal flora and allow more dangerous
Term
What is the mechanism of action on penicillin based drugs?
Definition
Penicillins weaken teh cell wall, causing bacteria to take up excessive amounts of water and rupture. They work by two actions.  Inhibition of transpeptidases and disinhibition of autolysins.
Term
What does pen. bind to?
Definition
penicillin-binding proteins.  They are named as such because pen. must bind to them to produce antibacterial effects.
Term
What is the difference in gram positive and gram negative binding for penicillin?
Definition
Penicillin effectivley attacks gram positive bacteria but cannot penetrate the outer membrane of gram negative cells.
Term
What do Beta-lactamases do?
Definition
They cleave the beta-lactam ring in penicillin rendering it ineffective.
Term
How do gram positive and gram negative bacteria treat beta-lactamases differently?
Definition
The g+ bacteria produce large amounts of B-L and discharge it in to the local medium. G- produce small amounts and secrete them into the periplasmic space.
Term
Where are penicillins derived from?
Definition
6-aminopenicillanic acid.
Term
What are the three salts of penicillin G?
Definition
Potassium penicillin G, Procain Penicillin G, and benzathine penicillin G
Term
T/F If and individual is allergic to Penicillin G they will in 5% to 10% of cases be allergic to cephalosporins and carbapenems.
Definition
True.
Term
What is the allergen in Penicillin?
Definition
Penicillin iteslf is not an allergen, however with degradation the small molecules form haptens with proteins and this can cause a reaction.
Term
What is the major antigenic determinant reagent?
Definition
benzypenicilloyl-polylysine
Term
What does the minor determinant mixture detect?
Definition
It detects antibodies that mediate immediate allergic responses (anaphylaxis)
Term
How do aminoglycosides and pen. work together and against each other?
Definition
They work because Pen. defeats the cell wall allowing aminoglycosides to get inside the cell. They work against each other because they two can react in solution. The solution to this problem is to administer them in seperate IV solutions so that the reaction doesn't occur.
Term
What are the 3 agents that are penicillinase-resistance?What are they used against? (ONLY)
Definition
nafcillin, oxacillin, dicloxacillin.
Staph. aureus and staph. epidermis
Term
What are the two broad-spectrum penicillins?
Definition
Ampicillin, amoxicillin
Term
What are extended-spectrum penicillins used for?
Definition
Primarily for infections with P. aeruginosa. These infections often occur in the immunocompromised host and can be very difficult to eradicate.
Term
What 3 drugs are appropriate for use with patients that are allergic to Pen.?
Definition
Vancomycin, erythromycin, and clindamycin.
Term
How are penicillins eliminated?
Definition
Kidney
Term
Can Pen. G be adminstered orally?
Definition
NO. It is unstable in the stomach, IM injection or IV.
Term
What is the active area of a cephalosporin?
Definition
The beta-lactam ring.
Term
How do cephalosprins work?
Definition
They act by binding to penicillin-binding proteins and disrupt cell wall synthesis and activate autolysins. Death is caused by autolysis.
Term
In order what is the least to most resistant to betalactamases?
Definition
1st gen 2nd gen and then finally 3rd and 4th gen are most resistant.
Term
What happens from 1st gen to 4th gen cephalosprins?
Definition
Increasing activity against gram-negative bacteria and anaerobes, increasing resistance to destruction by beta lactamases and increasing ability to reach the CSF.
Term
t/f cephalosporins are absorbed by the GI tract well.
Definition
False, they must be given parenterally.
Term
What two cephalosporins are not eliminated by nonrenal routes?
Definition
cefoperazone and cefriaxone.
Term
What three cephalorpsorings can NOT be taken with alcohol?
Definition
cefmetazole, cefoperazone, cefotetan. They result in a disulfuram like reaction causing intense sickness.
Term
What are carbapenems? What are the 3 drugs?
Definition
Beta-lactam antibiotics that have very broad antimicrobial spectra. imipenem, meropenem, and ertapenem.
Term
What is the mechanism for imipenem?
Definition
imipenem binds to two pbps (pbp1 and pbp2) causing lysis. It is resistant to almost all beta-lactamases.
Term
What is the primary introduction route and how does the body eliminate imipenem?
Definition
Parenterally, and it is primarily renal. it is inactivted by depeptidase.
Term
What are teh adverse effects of imipenem?
Definition
Gastrointestinal effects are most common with hypersensitivy reactions that have also occur.
Term
How does Vancomycin work?
Definition
inhibits cell wlal synthesis and thereby promotes bacterial lysis and death. it however does not interact with PBPs
Term
T/F Vanco. is a wide spectrum drug.
Definition
False, it is only active acainst gram positive bacteria. Staph aureus and staph epdiermidis.
Term
What is the most serious effect of vanco?
Definition
ototoxicity. Hearing impairment can be reversible but not always. risk is increased by high doses and longterm treatment. Rapid infusion can cause rash, pruritus, urticaria, tachycardia, and hypotension.
Term
How do tetracyclines suppress bacterial growth?
Definition
by binding to the 30s ribosomal subunit and thereby inhibit binding of transfer RNA to the messenger RNA-ribosome complex. PRotein synth is then halted.
Term
What diseases are tetracyclines 1st line for?
Definition
rickettsial diseases chlamydia trachomatis brucellosis cholera pneumonia by mycoplasma pneumoniea lyme disease anthrax and gastric infection with h. pylori.
Term
T/F tetracyclines are used to treat acne?
Definition
True.
Term
What two tetracylcines are used to treat peridontal disease? Which is used in pill form and which is topical?
Definition
doxycycline is in 20 mg twic daily pills and minocycline is topical.
Term
What should tetracyclines not be administerd with?
Definition
calcium supplements, milk products, iron supplements, magnesium containing laxatives, and most antacids. This is because it is a chelating agent.
Term
How are tetracyclines elimnted?
Definition
Kidneys and liver. All tetracyclines are excreteed by the liver into the bile. After the bile enters the intestine most tetracyclines are reabsorbed. Ultimate elimination of short and intermediate acting tets is in urine. Long acting tets are eliminated by the liver as metabolies.
Term
What are the effects on bones and teeth by teterocyclins?
Definition
Teterocyclins bind to calcium in developing teeth resultin gi n yellow or brown discoloration. Hypoplasia of thee namel may also occur.
Term
What is the minimal inhibitory concentration?
Definition
concentration of antimicrobial that inhibits growth in 18-24 hours.
Term
What is minimal bacterialcidal concentration?
Definition
minimum concentration that kills 99.9% of the cells.
Term
What are bacteriostatic agents best used for?
Definition
uncomplicated host infections that the host body can take care of if just kept in check. NOT FOR NEUTROPENIA in patients. If they have no immune system slowing down the bug will not help.
Term
Tetreacyclines can cause what in the liver and kidneys?
Definition
Fatty infilltration and can exacerbate renal impairment in patients with pre existing kidney disease.
Term
What are macrolides?
Definition
broad spectrum antibiotics that inhibit bacterial protein synthesis. They are called macrolides because they are large molecules.
Term
Where does erythromycin bind to?
Definition
50s subunit on the ribosome to block addition of new amino acids to the growing peptide chain.
Term
What two ways can bacteria become resistant to erythromycin?
Definition
1L production of a pump that exports the drug
2: modifications (by methylation) of target ribosomes so that binding of erythromycin is impaired.
Term
What is erythromyacin a possible replacement for?
Definition
Pen. G as it doesn't ignite the typical allergy
Term
What are the first line treatment uses for erthromycin?
Definition
Legionella pneumophillia (legionnaires' disease, bordetella pertussis, whooping cough. Diptheria, urethritis, cervicitis, streptococus pyrogenes and streptococcus pneumoniae.
Term
What are the adverse effects of erythromycin?
Definition
Gastrointestinal effects, Liver injury form the erythromycin estolate version. QT prolongation and sudden cardiac death
Term
What are drug interactions with erythromycin?
Definition
By inhibition of hepatic P450 enzymes elevated levels of all drugs can occur. Theophylline, carbamazepine, and warfarin are of particular importance. Erythromycin should not be combined with drugs that inhibit erythro. metabolism. These are verapamil, diltiazem, HIV protease inhibitors and azole antifungal drugs.
Term
Clindamycin can cause what problems?
Definition
it can promote secere antibiotic associated pseudomembranous colitis. This condition can be fatal.
Term
How does clindamycin work?
Definition
it acts by binding to the 50s subunit of bacterial ribosomes. It is the same site as erythromycin and so they can antagonize each other.
Term
What is clindamycins antimicrobial spectrum?
Definition
It is active against most anerobic bacteria (G+ and G-) and most areobic G+ microbes.
Term
What is AAPMC and what does Clindamycin do to make it worse?
Definition
Antibiotic-associated pseudomemembranous colitis. It is caused by a suprainfecton of the bowel by C. difficile. It is characterized by profuse, watery diarrhea, abdominal pain, fever and leukocytosis. Left untreated it could be fatal.
Term
What is linezolid a first class member of?
Definition
oxazolidinones
Term
How is Linezolid useful?
Definition
it is useful because it has activity against multidrug reistant gram positive pathogens, including vancomycin resistant enterocci and methicillin-resistant staph. aureus (MRSA)
Term
What is the mechanism of linezolid?
Definition
It binds to the 23S portion of the 50S ribosomal subunit.
Term
What are aminoglycosides composed of?
Definition
two ore more amino sugars connected by a glycoside linkage.
Term
What is the mechanism of action for aminoglycosides?
Definition
They bind to the 30s ribosomal subunit, and thereby cause protein synthesis inhibition, premature terminatino of protein synthesis, and production of abnormal proteins
Term
What are aminoglycosides limited to attacking?
Definition
aerobic gram negative bacilli. Escherchia colik, Lebsiella pneumoniae, serratia marcescens, proteus mriabilis, and psudomans aeruginosa.
Term
How well and what types of administration of aminoglycosides are used?
Definition
1% and parenterally.
Term
How are aminiglycosides eliminated?
Definition
primarily by the kidney, they are not metabolized.
Term
What can cause interpatient variation in absorption of aminoglycosides?
Definition
age,m percent, pahtophysiology.
Term
What are adverse effects of aminoglycosides?
Definition
ototoxicity, nephrotoxicity,neuromuscular blockade and hypersensitivity
Term
Why do aminoglycosides cause ototoxicity?
Definition
They can accumulate within the inner ear causing cellular injury. The risk of ototoxicity is related primariliy to excessive trough levels.
Term
Why is ototoxicity caused by high trough levels of aminoglycosides?
Definition
This is because when trough levels remain persistently elevated, aminoglycosides are unable to diffuse out of inner ear cells and hence the cells are exposed to the drug continuously.
Term
How is nephrotoxicity related to dosage?
Definition
Total cumulative dose of aminoglycosides. it typically results in acute tubular necrosis.
Term
t/f penicillins and aminoglycosides are frequently employeed together.
Definition
True, pen. breaks down the cell wall and aminoglycosides kill the cell.
Term
What is the dosing schedule of aminoglycosides?
Definition
one large dose once a day in modern applications.
Term
What are the outstanding features of amikacin?
Definition
it has the broadest spectrum of action against gram-negative bacilli and all of the aminoglycosides, amikacin is the least vulnerable to inactivation by bacterial enzymes.
Term
What are sulfonamides structureal analogs of?
Definition
para-aminobenzoic acid.
Term
What is the mechanism of sulfonamides?
Definition
they hnhibit synthesis of folic acid.
Term
What are the therapeutic uses of sulfonamides?
Definition
urinary tract infections (sulfamethoxazole)
Term
What are the adverse effects of sulfonamides?
Definition
hypersensitivity reactions, blood dyscrasias, kernicterus, and renal damage.
Term
What is the most severe hypersensitivity reaction of sulfonamides?
Definition
stevens-johnson syndrome, a rare reaction that has a mortality rate of about 25%. Symptoms include widespread lesions of the skin and mucous membranes, together with fever, malaise, and toxemia.
Term
What are the hematologic effects of sulfonamides?
Definition
hemolytic anemia in patients whose red blood cells have a genetically determined deficiency in glucose-6-phosphate dyhydrogenase. Most common in African Americans and people of mediterranean origin.
Term
What is kernicterus?
Definition
it is a disorder in newborns caused by deposition of bilirubin in the brain. B. is neurotoxic and can cause severe neurologic deficits and even death.
Term
What is crystsalluria?
Definition
because of low soluability sulfonamides can cause crystalline aggregates that can cause irritation and obstruction sometimes resulting in anuria and even death.
Term
What is sulfamethoxazole combined with? is it an intermediate or short acting sulfonamide?
Definition
Trimethoprim, intermediate.
Term
How does trimethoprim work?
Definition
it inhibits dihydrofolate reductase from working.
Term
What are adverse affects of trimethoprim?
Definition
megaoblastic anemia, thrombocytopenia, and neutropenia can occur in individuals with pre-existing folic acid deficiency. pregnancy useage can cause fetal malformations in animals but no cases observed in humans.
Term
How does the trimethoprim/sulfamethoxazole combination work?
Definition
they work by inhibiting consecutive steps in the synthesis of tetahydrofolic acid. SMZ acts first to inhibit paba incorperation. TMP then inhibits dihydrofolate reductase.
Term
What are the side effects of trimethoprim+sulfamethoxazole?
Definition
Hypersensitivty, stevens-johnson syndrome (with long-acting agents) hematological reactions, incerased serum creatinine concnetration and drug interactions with protein binding displacement and competition for metabolizing enzymes.
Term
What is the clinical manifestation of acute cystitis?
Definition
dysuria, urinary urgency, urinary frequency, suprapubic discomfort, pyuria, and bacteriuia.
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