antibiotics Flashcards
list the beta lactams
penicillin
cephalosporins
carbapenems
monobactams
types of penicillin
narrow and broad spec
broad spec penicillins
Carboxypenicillin
Aminopenicillin
Ureidopenicillin
groups of antibiotics
- B lactams
- Glycopeptides
- Aminoglycosides
- Tetracycline
- Macrolides
- Amphenicols
- Lincosomide
- Fluoroquinolones
- Sulphonamides
- Nitroimidiazole
examples od nitromidazo;es
Metromidazol
b. Timidazol
principle for prescribing antibiotics
- MUST HAVE A BACTERIAL INFECTION (duh)
- Better to know type of MO
- character of the disease
- the patient
- pharmacological characteristics of the drug
- localization
- clinical manifestations
what type of antibiotic is given to immunosupressed patients
bacteriacidal
which factors infulence the efffective therapeutic concenctration at the site of infection
Cmax - max [serum] that a drug achieves in a specified compartment of a test area of the body before the 2nd dose. 2. Tmax – amount of time a drug is present at Cmsx 3. AUC – ‘area under the curve’ àtotal drug exposure across time. The curve represents total amount of drug absorbed by the body 4. T ½ 5. MIC – [lowest] of a drug which prevents visible growth of bacterium.
what is the Cmax
max [serum] that a drug
achieves in a specified compartment
of a test area of the body before the
2nd dose.
what is the t max
Tmax – amount of time a drug is
present at Cmsx
what is the AUC
area under the curve’ àtotal
drug exposure across time. The
curve represents total amount of
drug absorbed by the body
what is MIC (minimal inhibitory concentration)
[lowest] of a drug which
prevents visible growth of
bacterium.
how many types of antibiotics are there according to their absorption
type 1: aminoglycosides and fluroquinilones
type 2: b lactam
type 3: tetracycline and azithromycin
type 1: aminoglycosides and fluroquinilones absorption
Fast and powerful antibacterial effects - Less ADRs when peak conc achieved - Conc dependant effect!*] - ideal dose MUST ensure maximal high plasma conc
type 2 b lactams
highest bacterial efficacy when [serum] are 2-4 > MIC - ideal dose regimen is maximal duration of effect between 2 doses.
type 3 tetracylcines and azithromycin
Possess mixed type
pharmacokinetic and pharmaco
dynamics
application of aminoglycosides
single daily
dose application.
Ratio of Cmax/ MIC > 10
determines antibacterial effect.
flouroquinolones
à AUC/MIC
ratio
Gram +ve = 25-30
Gram -ve = 100-125
when should the antibiotic theraapy be changed
after 48-72 hours
Concentration dependent antibiotics: Aminoglycosides and flouroquinolones
ntibiotics which eradicate pathogenic bacteria by achieving high concentration at the site of binding
ntibiotics which eradicate pathogenic bacteria by achieving high concentration at the site of binding
Time dependent antibiotics: penicillins, cephalosporins, carbapenems, monobactams), clindamycin, macrolides (erythromycin, clarithromycin), oxazolidinones (linezolid).
he time that serum concentrations remain above the MIC during the dosing interval (t>MIC)”.They show optimum killing response when the time that the drug remains above the MIC is either equal or greater than 50% of the dosing interval.
when is combination therapy indicated
Avoid drug resistance especially in diseases like TB 2. Immunocompromised patients 3. Prophylaxis in heavy operations – i.e intraabdominal ops 4. Widening antimicrobial spectrum in critical cases i.e septicaemia 5. Rx of mixed infections (aerobes and anaerobes )
types of antibiotics based on mechanism of action
- Bactericidal effect on fast divided microbes + microbe spores – aminoglycosides, flouroquinolones
- Bactericidal effect on fast divided microbes – B lactams + vancomycin
- Bacteriostatic effect – Tertacycline , macrolides chloramphenicol, lincozamides morning
which combinations are profitable
group 1 and 2
group 1 and 3
group 2 and 2
group 3 and 3
which drug combinations are contraindicated
group 2 and 3 decrease effect( except B lactams, sulphonamides + metronidazole)
group 1 and 1 is irrational
which operations are require prophylactic antibiotic coverage
o Cardiovascular ops o Neurosurgery o Abdominal operations o Appendectomy ( o Application of prophylactic Abs
§ For 48 hours
§ IM – before op
§ IV – during op
which disease inidcate prophylactic antiobiotic coverage
Meningococcus induced meningitis
Neutropenia
Animal bites
Acute joint rheumatism
which antibiotics induce CYP450A3
rifampicin
what drugs have their plasma concentration decreased by rifampicin
a. Warfarin
b. Cyclosporin
c. Glucocorticoids
d. Ketoconozol
e. Cardiac glycosides
f. Verapamil
which drugs inhibit CYP450A3
Erythromycin, flouraquinolones and isoniazid
which antibiotics cause disulfiram reaction w/ alcohol
Metronidazol + tinidazole
antacids cause decreased absorption of which drugs
macrolides
tetraclyclines
flouroquinolones
adr’s of antibiotics
- gastrointestinal disrubances
- dysbacteriosis
- allergy
- hepatotoxicity
- nephrotoxicity
- myelotoxicity
- neurotoxicity
- bones and teeth
GIT disturbance
irritation observed especially w/
GIT
tetracyclines + erythromycin.
• Wide spec = alter the intestinal and oral
microflora
• N/V , anorexia abdominal pain , diarrhoea
Dysbacterioris
ncomycin/ clindamycin à development of pseudomembranous enterocolitis can occur à V DANGEROUS (swelling and overgrowth of large intestine d/t growth of C. difficile)
Hepatotoxicity
Abs that have bile excretion
mainly for eg tetracycline, erythromycin.
And rifampicin
aundice is observed after long term use
with tetra, streptomycin + lincomycin
Myelotoxiitiy
Heavy BM disturbances seen w/ long term rx
w/ chloramphenicol
Neurotoxic effects
Aminoglycosides and vancomycin effect the
8th vestibular cochlear nerve!
Optic nerve – streptomycin
chloramphenicol
Bone + teeth
Tetracyclines can accumulate in teeth and bones • Can destroy their growth and form • CI in children up to 7 yrs • Quinolones à damage chondroithal catrlidge . CI in children upto 12
what happens to antibiotics in liver failure
Metabolism of Abs may be delayed which leads to the ^ in [plasma] and ^
risk of ADRs
• When clin lab results show liver malfunction ie ^ Br AST + ALT enzyme ^ -
reduce dose
which antibiotics have delayed metabolism in liver diseases
Erythromycin
Clindamycin
Lincomycin
Chloramphenico
how does kidney failure affect antibiotics
increased half life excretion time causing increase plasma volume of antibiotics thus increasing the risk od ADRS . the dose should be reduced or the dosing intervals should be increased
which antibiotics have increased half life excretion time in kidney failure
Aminoglycosides
Floura
Beta lactams
Vanco etc
approach to type 1 (conc) antibiotics in kidney failure
keep dose unchanged and only ^ dose interval
pproach to type 2 (time) antibiotics in kidney failure
decrease dose only – ensures optimal t> MIC ratio
Which anitibiotics can be applied in pregnancy
category b antibiotics e.g.penicillins: amoxicillin, clavulanic acid, cefalosporins, macrolides, aztreonams
category c antibiotics
e.g. imipenems, aminoglycosides, chloramphenicol , flouroquinolones
antibiotic approach to community acquired pneumonia
Specific Abs not good d/t late and low rate microbial lab results
• EMPIRICAL THERAPY is the way to go!
• Recommended therapy is B lactams w/ wide spec
• In pts w/ heavy infection, combine above w/ macrolides
DO NOT COMBO W/ AMINOGLYCOSIDE
antibiotic approach to hospital acquired pneumonia
Combo therapy cos mixed infections
• Fluoroquinolones not recommended ads they ^ resistance in ambulatory pts
• Always paraentral BUT when combo – 2nd drug is applied orally
• Duration = paraentral – 5 to 7 days + 5 days oral therapy
antibiotic approach to urological infections
Causative agent is usually E.coli
Aminoglycosides + B lactams and 3rd gen
• NOT co – trimoxazole and floura d/t developed resistance.
antibiotic approach to acute prostatitis
causative agents are : strep pne, HI and Moraxella catarhallis.
Use quinolones – 1 month
• They have good penetration In prostate secretes and accumulate in prostate
gland
antibiotic approach to Acute and chronic
sinusitis
ACUTE: caused by trep pne, HI and Moraxella catarhallis.
• 1st line Rx – amoxicillin (+/- clavulanic acid)
• 2 weeks
• Cefuroxime – also used
• If no imoprovemnt within 72 hrs then proceed with application of
flouraquinalones – levoflaxicin and moxifloxacin
• In cases of B lactam allergy use – clarithromycin azithromycin etc
• Penicillin , erythromycin and 1st gen – not recommended
antibiotic approach to Osteomyelitis
Use paraentral drugs which penetrate bines and joints à oral therapy
• 4-6 weeks
• PRSPs and 3rd gen
