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64 Cards in this Set
- Front
- Back
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Give an example of a macrolide.
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Erythromycin
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Are macrolides lipophilic or hydrophilic?
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lipophilic - get better tissue penetration and into cells
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What is the spectrum of action of macrolides?
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Gram (+); narrow spectrum; alternate treatments for mycobacterial and chlamydiphilia infections
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What is the mechanism of action of macrolides?
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-work on the 50s ribosome --> inhibit protein synthesis by inhibiting protein elongation
Exception is rifampic. It is cidal and works on RNA (decreases activity of RNA polymerase, preventing transcription) |
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How can macrolides be used?
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p/o, parenterally, topically
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Is rifampin (a macrolide) static or cidal - how does this differ from the other macrolides?
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rifampin is cidal - all the other macrolides are static
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What is the major adverse effect of macrolides?
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-GI (diarrhea)
-decreases in microsomal activity in all but rifamin are possible |
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How must a lipophilic drug, like macrolides, need to be prepared if it is to be taken p/o. Why?
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-must be coated b/c stomach acid can be detrimental to the molecule
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How are macrolides cleared?
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oxidized in the liver microsomes; parent compound and metabolites in enerohepatic circulation
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Is rifampin a reserve antibiotic?
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YES!
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What other action does rifampin have as opposed to the other macrolides?
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-effective against mycoplasma, anaerobes, and some viruses in additions to normal macrolide targets
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How are macrolides normally used - to treat what?
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-to treat general soft tissue infections
-as an alternative to penicillin -Tilmicosin is given SC for bovine respiratory disease -feed addatives |
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Give an example of a Lincosamide.
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clindamycin
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What is the chemistry of Lincosamides?
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-hydrophilic and hydrophobic
-weak bases |
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What is the spectrum of action of Lincosamides?
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Like Gram (+), but also like a broader spectrum (anerobes and mycoplasma, protozoa)
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What are some adverse effects of Lincosamides?
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-diarrhea can be life-threatening in some species (Guinea Pigs, Hamsters, rabbits, horses)
-can cause NM blockade |
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What is the mechanism of action of Lincosamides?
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-static - act on the 50S ribosome, including 50s ribosome of G+ bacteria (mostly)
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What is unique about Clindamycin?
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-has a Cl on molecule which increases lipophilic action
-can be used in a bone infection (others are not lipophilic enough); will distribute to bone, but not CSF |
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How are lincosamides dosed?
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BID, TID - half life is greater than beta lactams
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Is p/o absorption for clindamycin or lincomycin greater?
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clindamycin>lincomycin
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How are lincosamides metabolized?
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-Phase I oxidation occurs with fecal excretion and urinary excretion - both 50%
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Name the two classes of antifungals.
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(1) Polyenes - antibiotic/antifungal
(2) Imidazoles |
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What is the chemistry of polyenes?
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large MW compunds; weak acids that have hydrophilic and lipophilic regions (amphoteric)
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How are polyenes normally administered?
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(1) IV (diluted sufficiently to dissolve)
(2) topically |
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Give an example of a polyene?
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amphotericin B
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What is the mechanism of action of polyenes?
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-most effect works on membrane and sterols in membrane - causes a leaky membrane
-since the patients have these too, there are some side effects |
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What are adverse side effects of polyenes?
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(1) GI problems - nausia - vomiting
(2) >80% of patients will develop nephrotoxicity - exaggerated if other renal-targeting drugs are used concurrently (3) drug fever (when given IV)- can be decreased by pretreating with corticosteroids (4) anemia s |
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What are polyenes used for?
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serious systemic infections (IV) or serious non-systemic infections
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Are polyenes safe?
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no - only used for the life threatening fungal infections
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How are polyenes used?
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IV and topically
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Are polyens highly protein bound?
....highly metabolized? |
yes - 95%
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How are polyenes metabolized?
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-microsomal metabolized and excreted in the urine (slow)
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Give an example of an imidazole.
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ketoconazole
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What is the biggest use of imidazoles?
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topical
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What do imidazoles target?
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-target sterol membrane of fungi - make it leaky
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Are imidazoles cidal or static?
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can be both depending on dose
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What does imidazole prevent from forming in fungi?
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- decreases ergosterol synthesis
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What type of side effect might you get if imidazoles are administered p/o?
topically? |
GI upset - used for systemic use
topically - very safe! |
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What are imidazoles used for?
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-p/o administration common for systemic antifungal effects, though not as efficacious as IV amphotercin B
-p/o for fungal infections of the integumentary system -topical widespread |
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What are ionophores used for? Name some other things about them.
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-feed additives/ growth promotants
-NA channel target -cattle only - not good in exercising animals (causes heart attack) |
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Name 3 groups of anithemintics.
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(1) Avermectins
(2) Benzimidazoles (3) Tetrahydropyrimidines |
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What is the mechanism of action of acermectins?
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Cl channel target (GABA/glutamate)
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How are avermectins administered?
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-orally, parenterally, topically
- fecal excretion -stay in the body a long time |
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What is the action of benzimidazoles?
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binds to parasite tubilin
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How can benzimidazoles be administered?
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p/o, variable through the GI tract;
-stay in rumen - are excreted thru fecal |
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What is the target of tetrahydropyrimidines?
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nicotinic agonists
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How are tetrahydropyrimidines administered?
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orally, parenterally, topically
-urinary and fecal excretion |
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What are some mechanisms of action of antiviral drugs?
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(1) decrease entry and/or affect coating
(2) transcription /translation (nucleus) - MOST COMMON - decrease viral replication (3) interfere with viral assembly, maturation and or release (4) improve host resistance (4) maturation and release (includes H1N1) |
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What are adverse effects of anitvirals?
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-difficult to impossible to treat
-species specificities -effective drugs are toxic to the host which may preclude systemic use -prevention is better than treatment |
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What is the type of virus we are most likely to treat?
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-herpes (opthalimic) - used topically so no systemic effects
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How do nucleoside analogs as antiviral drugs work - mechanism of action?
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-serve as false substrates for DNA polymerase, keeping the virus from replicating - look like nucleic acids
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Describe the use of antiviral, biological immune modulators.
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(1) immunoglobulins - use IgG and IgA to boost the immune system
(2) interferon alpha 2A - used to treat malignant melanoma, feline viruses, and LA respiratory disease (3) lymphocyte T-cell immunomodulator - a polypeptide that regulates lymphocyte and cytokine production (for FeLV and FIV) |
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What is the difference in dosing of human vs. vet med interferon?
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-human: millions of units via parenteral route
-vet med: 100-1000 units orally (p/o); stimulate immune system |
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What are the role of biologicals?
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-to help body fight infections
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What type of cancers are easier to treat?
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-growing, small tumors
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What is the action of anti-cancer drugs?
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WORK on CELL CYCLE
(1) S phase - synthesis phase (false subsrates) (2) M phase - no division (3) generally cytotoxic no matter what stage |
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What are the (goals) objectives of treating cancers?
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(1) cure - thyroid, other than that it is unlikely
(2) remission - no clinical signs (3) reduction - so can do surgery (4) palliation - improve quality of life |
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What are the factors contributing to realization of treatment goal?
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(1) diagnosis is important
(2) treatment modalities (3) client, patient, DVM (4) resistance |
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Name some treatment modalities for cancer.
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Primary - surgery, radiation, chemotherapy
Secondary - cryosurgery, hyperthermia, immunotherapy |
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What are some toxicities of cytotoxic agents?
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(1) to DVM and staff - need protective clothing, special prep
(2) to patient - have toxicity to normal cells (kidney, bone marrow, skin/hair, GI tract) |
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What are the manifestations of toxicity in cancer drugs?
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marrow cells - immunosuppression, anemia
gi cells - nausea, vomiting, ulceration, diarrhea kidney - nephrotoxicity reproductive cells - loss of function other - loss of hai |
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What are the methods for decreasing toxicity and increasing usefulness?
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(1) dosing - use surface are instead of weight, pulsing
(2) consider adjuvants to decrease adverse effects - antiemetics, hydration analgesics (3) consider resistance (4) use combinations of drugs - |
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What are the mechanisms for resistance in cancer drugs?
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(1) decrease uptake
(2) increase clearance (3) increase efflux (4) inactivation (5) change in target (6) increase repair of DNA damage |
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When using combination drugs to treat cancer, what are the rules?
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each drug must be active against the tumor; toxicities should not overlap; each drug should have a different mechanism of action
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