antibiotics 1 Flashcards
what is the classname of nitrofurantoin
nitrofurantoin
indiction for nitrofurantoin
1st line treat for uncomplicated UTI
MOA for nitrofurantoin
it is metabolised in bacterial cells by nitrofuran reductase and its active metabolite damages bacterial DNA and causes cell death
Nitrofurantoin is active against the G-ve (eg E.coli) and G+ve ( Staph sap) that commonly cause UTI
contraindication for nitrofurantoin
should not be use in pregnant women or for bodies tin the first 3 months of life
renal impairment - impaired excretion inc toxicity and reduces efficacy due to lower urinary drug conc
caution for chronic use for long term prevention - inc risk of side-effect esp in elderly pts
side effect for nitrofurantoin
GI upset (N+v)
can cause delayed
hypersensitivity
turn urine yellow or dark
can cause chronic pulmonary reactions (inc inflammation and fibrosis)
hepatitis
peripheral neuropathy
in neonates - haemolytic anaemia - RBC can not mop up nitrofurantoin-stimulated superoxides
interaction of nitrofurantoin
N/A
typical dose of nitrofurantoin
50-100mg 6 hourly
what is the class name for trimethoprim
trimethoprim
what are 2 examples of trimethorim
trimethoprim and co-trimoxazole (trimethoprim and sulfamethoxazole)
main indication for trimethoprim
first choice for uncomplicated UTI
co-trimoxazole is used to treat and prevent pneumocystis pneumonia in people with immunosuppression
MOA for trimethorpim
trimethoprim - inhibits bacteria folate synthesis (as bacteria are unable to use folate present in human body) and so it is bacteriostatic
sulfonamides also inhibit bacterial folate synthesis but slightly different pathway to trimethoprim, but together with trimethoprim, a complete bactericidal action
contra-indication for trimethoprim
first trimester of pregnancy (folate antagonist)
avoid use in ppl with folate deficiency
a reduced dose should be used in ppl with renal impairment
cautious use in neonate, elderly and ppl with HIV
side effect of trimethoprim
GI upset (N+V) skin rash (rare) can impair haematopoiesis causing haematological disorder such as megaloblastic anaemia, leucopenia, thrombocytopenia can also cause hyperkalaemia elevation of plasma creatinine conc
interaction of trimethoprim
use with potassium-elevating drugs eg (aldosteron antagonist, ACEi, angiotensin receptor blockers) - predisposes to hyperkalaemia
use with other folate antagonist eg methotrexate and drugs that inc folate metabolism - inc risk of adverse haematological effects
can also enhance the anticoagulant effect of warfarin by killing normal gut flora that synthesise vit K
what is the doses of trimethoprim
200mg 12 hourly
what are the different examples of penicillin
benzylpenicillin, phenoxymethylpenicillin
what are some examples of broad spectrum penicillin
amoxicillin and co-amoxiclav
MOA for broad spectrum penicillin
Beta lactam
amoxicillin - beta-lactam has side chain attached to the beta lactam ring and this side chain can modified to increase antibacterial ability. amoxicillin has additional amino acids group for inc ability
co-amoxiclav - addition of beta-lactamase inhibitor, clavulanic acid, inc the spectrum of antimicrobial activity to include beta-lactamase-producing bacteria eg staph aureus, gram -ve anaerobes)
main indication for broad spectrum penicillin
- empirial treatment for pneumonia (can be due to both gram +ve and gram -ve pathogens
- empirial treatment for UTI (most common caused by E.coli)
- part of combined treatment for H.pylori-associated peptic ulcers
main contra-indications for broad spectrum penicillin
pt at inc risk of C.Diff infection
allergy dose should be reduced in those with severe renal impairment
adverse effect of broad spectrum penicillin
GI upset eg N+V
antibiotic colitis- normal flora got killed
allergy
cholestatic jaundice - co-amoxiclav
interaction of broad spectrum penicillin
reduce renal excretion of methotrexate - inc risk of toxicity
can enhance the anti-coagulant ability of warfarin by killing gut flora which produce Vita K
typical dose for amoxicillin
severe infection - 1g 8-hrly then switch to oral
mild-moderate - 250-500mg 8 hrly
what are the group name for benzypenicillin, phenoxymethypenicillin
penicillins
MOA for benzypenicillin and phenoxymethypencillin
Beta lactam
the side chain to the beta lactam ring is the characteristic for the medicine
main indication for benzypenicillin and phenoxymethypenicillin
- strep infection - incl tonsillitis, pneumonia (combine with macrolide if severe), endocarditis and skin and soft tissue infections (added to fluxcloxacilline if severe)
Costridial infection eg tetanus
meningococcal infection eg meningitis, septicaemia (blood poisoning)
contra-indication for benzypenicillin and phenoxymethypenicillin
pt with renal impairment
allergy
side effect for benzypenicillin and phenoxymethypenicillin
allergy
CNS toxicity - can occur with high dose of penicillin
interaction of benzypenicillin and phenoxymethypenicillin
methotrexate - pencillin reduce renal exercretion - inc conc
what is penicillin V
phenoxymethypenicillin
what is an example of penicillin with antipseudomonal
piperacillin with tazobactam (Tazocin)
MOA for Tazocin
beta lactam
for piperacillin, side chain = a form of urea which improve affinity to penicillin binding proteins - inc spectrum of antimicrobialactivity to include pseudomonas aeruginosa
tazobactam - confers antimicrobial activity against beta lactamase producing bacteria eg staphy aureus, gram -ve anaerobes
main indication for Tazocin
reserved for severe infections - where broad spectrum of potential pathogens (incl pseudomonas aeruginosa) and antibiotic resistance is likely or pts who are immunocompromised
lowere Resp tract inf
UTI
Intra-abdominal sepsis
skin and soft tissue infection
contra-indication for Tazocin
caution in pt at risk of C.diff
allergy
renal impairment
side effect of Tazocin
GI upset
antibiotic associated colitis - killing of normal gut flora
allergy
interaction of Tazocin
methotrexate
inc risk of warfarin toxicity - killing of normal gut flora which produce vita K
which of the penicillin medication should be used with a pathogen which is penicillinase-resistant
Flucloxacillin
MOA for flucoxacillin
an acyl side chain protects the beta lactam from beta lactamases
makes flucloxacillin effective against beta lactamase producing staphylococci
MRSA resist the flucloxacillin by reducing penicillin binding affinity
contra-indication for flucloxacillin
renal impairment
allergy
side effect of flucloxacillin
GI upset
allergy
CNS toxicity - when high dose
interaction of flucloxacillin
methotrexate
what are some examples of cephalosporins and carbapenem
cefalexin and cefotaxime
meropenem ertapenem
MOA of ceflaxin and cefotaxime and meopenem and ertapenem
beta lactam ring but inhibit enzymes responsible for cross-linking peptidoglycanrs in the bacterail cell wall during cell growth
broad spectrum
both are more resistant to beta-lactamases than pencillin due to fusion of the β-lactam ring with a dihydrothiazine ring (cephalosporins) or a unique hydroxyethyl side chain (carbapenems).
main indication for cephalosporins and carbapenems
- oral cephalosporins - 2nd or 3rd line treatment options for UTI and resp tract infection
- IV injections of both types are reserved for severe or complicated infection
- cAN BE USED FOR MOST INFECTION DUE TO BROAD SPECTrum
contra-indication for cephalosporin and carbapenems
pt at risk of C.diff
allergy
carbapenems - caution in pt with epilepsy
renal impairment in both
side effect for cephalosporin and carbapenems
GI upset antibiotic associated collitis allergy CNS system toxicity - when high doses renal impairment
interaction of cephalosporins and carbapenems
warfarin
cephalosporins - inc nephrotoxicity of aminoglycosides
carbapenems - reduce plasma conc of valproate
examples for tetracyclines
doxycycline, lymecycline
MOA for doxycycline and lymecycline
inhibit bacterial protein synthesis
binds to ribosomal 30s subunit found specifically in bacteria - bacteriostatic
broad spectrum
indication for tetracyclines
acne vulgaris
lower RTI incl infective exacerbation of COPD, pneumonia and atypical pneumonia
chlamydial infection incl pelvic inflammatory disease
typhoid, anthrax, malaria and Lyme disease
contra-indication for tetracyline
oesophageal and bone - teeth deformity - avoid in infant as they are still growing, pregnancy, breast feeding
renal impairment
side effect of tetracycline
GI upset
ulceration and dysphagia
photosensitivity
discolour and hypoplasia of tooth enamel
intracranial hypertension - rare
interaction of tetracycline
They shouldn’t be given within 2 hours of calcium, antacids or iron
Enhance warfarin
indication for flucloxaillin
skin and soft tissue - eg cellulitis (with benzypenicillin)
Osteomyelitis and septic arthritis
endocarditis
