Pharmacology Exam II

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A chlorine substituted derivative of linomycin

clindamycin
Susceptible to clindamycin
- strep
- staph
- pneumo
- bacteroides
- gram + and gram - anaerobes
resistant to clindamycin
- enterococci
- most aerobic gram negative bacteria
clindamycin is a bacterio____ agent

static
Mechanism of action for clindamycin
- bacterial protein synthesis inhibitor
- binds to the 50s of bacterial ribosome
mechanisms of resistance to clindamycin
- cross resistance with macrolides
- mutation of ribosomal receptor site
- modification of the receptor by methylase
- enzymatic inactivation of clindamycin
______ are intrinsically restistant to clindamycin because of poor permeability of the outter membrane

gram negative aerobes
Pharmacokinetics of clindamycin
- 90% protein bound
- penetrates most tissues except CNS
- actively taken up by macrophages
- half life of 2.5 hrs
Metabolism of clindamycin
- metabolized by the liver to active metabolites
- excreted in bile and urine
- no renal dosing necessary
Clinical uses of clindamycin
- skin and soft tissue infections
- community aquired MRSA skin infections
- treatment of penetrating abd. wounds
- female genital tract/pelvic abscess
- aspiration pneumonia
- prophylaxis for dental procedures against endocarditis in pt with valvular heart disease
Effetive for moderate to moderately sever pneumocystis jirovec pneumonia in AIDS patients

clindamycin + primaquine
Used for AIDS related toxoplasmosis of the brain

clindamycin + pyrimethamine
Adverse effects of Clindamycin
- Diarrhea/nausea/entercolitis
- skin rash
- impared liver function
- neutropenia
Chloramphenicol solubility

poorly soluble in water
chloramphenicol succinate

highly water soluble
Mechanism of action for chloramphenicol
- inhibitor of protein synthesis
- binds 50s subunit of ribosome
Chloramphenicol spectrum
- bacteriostatic
- aerobic
- anaerobic
- gram +
- gram -
Chloramphenicol is active against _____ but not_____.
- rickettsiae
- chlamydiae
Chloramphenicol may be bacteriocidal to
- H. influenzae
- N. Meningitidis
Resistance to chloramphenicol emerges through

the ability of target organisms to produce chloramphenicol acetyltransferase that inactivates the drug
oral absorption of chloramphenicol

rapid and complete
chloramphenicol palmitate

prodrug that is hydrolized in the intestine
Chloramphenical distribution into tissues

widely distributed into all tissues and body fluids, even the CNS
Chloramphenicol metabolism

conjugation with glucuronic acid or reduction ti inactive aryl amines
Chloramphenicol excretion

90% urine
clinical uses of chloramphenicol

rickettsial infections such as typhus and rocky mountain spotted fever
Chloramphenical is rarely used because of
- potential toxicity
- bacterial resistance
- availability of alternatives
most lethal and most frequent reported rickettsial illness in the unites states.

rocky mountain spotted fever
Dosage adjustments for chloramphenical need to be made for patients with ____

hepatic failure
Chloramphenical is an alternative to beta lactam antibiotics in the treatment of _____ in _____ patients
- meningococcal or bacterial meningitis
- PCN allergy pt
A serious infection of the thin lining that surrounds the brain and spinal cord

meningococcal meningitis
Chloramphenicols is used topically for the treatment of

eye infections except chlamydial
ADRs with chloramphenicol
- N/V/D
- oral/vaginal candidiasis
- dose related suppression of RBC production
- aplastic anemia
condition where bone marrow does not produce sufficient new cells to replenish blood cells leading to increased risk of hemorrhage & bruising

aplastic anemia
Toxicity of chloramphenicol in new borns
- gray baby syndrome
- vomiting
- flaccidity
- hypothermia
- shock
- collapse
Drug interactions with chloramphenicol
- chloramphenical inhibits microsomal enzymes
- half lives and concentrations are increased in:
- phenytoin
- tolbutamide
- chlorpropamide
- warfarin
glycopeptide antibiotics

vancomycin
with the exception of flavobacterium, vancomycin is active against only

gram positive bacteria, particularly staph
Vancomycin stability
- water soluble
- quite stable
Mechanism of action for Vancomycin
- inhibits cell wall synthesis by binding d-ala-d-ala terminus of peptidoglycan pentapeptide
- inhibits cross linking
Resistance to vancomycin by enterococcie is due to the change of d-ala-d-ala to d-ala-d-_____. This results in loss of affinity for vancomycin.

lactate
Vancomycin is bacterio______ for ______ bacteria at 0.5 - 10 mcg/ml
- cidal
- gram positve
Most staph, b-lactamase producers, and organisms resistant to nafcillin and methicillin are killed my ___mcg/mL or less of Vancomycin

2 mcg/mL
Vancomycin kills staph slower than _____ and only acts on _____.
- PCN
- actively dividing cells
Vancomycin has synergisitc activity with ____ & ____ against Enterococcus faecium and faecalis.

gentamicin and streptomycin
Vancomycin absorption

poor oral absorption
Oral vancomycin used to treat

c. defficile
Vancomycin distribution after IV dosage

wide distribution
Vancomycin excretion

90% glomerular filtration
Main indications for vancomycin

sepsis or endocarditis caused by methicillin resistant staphylococci
Alternative regimen for treatment of enterococcal endocarditis in pt with serious PCN allergy

vanc + gent
Recommended for treatment of meningitis suspected or known to be caused by PCN resistant strains of pneumococcus
- Vancomycin + 1 of the following
- cefotaxime
- ceftriaxone
- rifampin
Recommended dosage for vancomycin

30mg/kg/day in two or three divided doses
clearance of vancomycin is directly proportional to

creatinine clearance
Adverse reactions with vancomycin
- in about 10% of pt
- phlebitis/irritation at injection site
- chills/fever
- ototoxicity/nephrotoxicity
- red man syndrome
Red man syndrome
- reaction to vanc
- develop w/in 5 to 10 min
- not a true allergy
- caused by release of histamine
- can be reduced by prolonging the infusion time

Author

Rx2013

65305

Card Set

Pharmacology Exam II

Description

Clindamycin, Cloramphenicol, Aminoglycosides

Updated

2011-02-09T19:44:35Z