penicillins Flashcards
PMP 4 interactions - vit K antagonists + methotrexate
- aconocoumarol: PMP potentially alters AC effect, monitor and adjust dose
- MTX: PMP predicted to increase risk of toxicity. monitor
- pheninidione: PMP may increase risk of bleeding events
- warfarin: PMP potentially alters AC effect of warfarin, monitor INR and adjust dose
name the 4 drugs that PMP interacts with
vit K antagonists - warfarin, acenocoumarol, pheninidione
MTX
PMP - take with or without food
Take this medicine when your stomach is empty. This means an hour before food or 2 hours after food
MOA Penicillins
bactericidal
act by inferring with bacterial cell wall synthesis
can you use penicillin in CNS infections
penetration into CSF if poor except with meninges are inflamed
important safety info - fluclox & hepatic disorders
cholestatic jaundice and hepatitis may occur rarely up to 2 months after treatment with fluclox has stopped
RF: admin for more than 2 weeks and increasing age
do not use in pt with Hx hepatic dysfunction associated with fluclox
use in caution in HI
careful enquiry should be made about hypersensitivity reactions to Beta lactam abx
can cholestatic jaundice and hepatitis occur even after fluclox has been stopped?
can occur up to two months after treatment with fluclox has been stopped
name 2 risk factors for choelstatic jaundice and hepatitis with fluclox
taking for more than 2 weeks
increasing age
what is the interaction between paracetamol and fluclox
caution
P has been reported to cause high anion gap metabolic acidosis when given with F
what are the 5 severe interactions with fluclox?
vit K antagonists - warfarin, pheninidone, acecoumarol (rosa of bleeding events/altered AC effect)
MTX (risk of toxicity, monitor)
paracetamol (caution, high anion gap metabolic acidosis)
the following electrolyte imbalance can occur with fluxloc, esp in high doses
potentially life threatening hypokalaemia - can be resistant to potassium supplementation ! hence regular monitoring of serum potassium recommended when using higher doses
diarrhoea frequently occurs during oral penicillin therapy. it is most common with …….
most common with BS penicillins, which can cause abx-associated colitis
who is at higher risk of anaphylactic reactions to penicillins
history of atopic allergy e.g. asthma, eczema, hay fever
patients with history of anaphylaxis, urticaria, or rash immediately after penicillin administration - should they be given a penicillin
no because at risk of immediate hypersensitivity
which characteristics indicate immediate hypersensitivity to penicillin
history of anaphylaxis, urticaria or rash immediately after penicillin
individuals with a history of a minor rash (non-confluent, non-pruritic rash restricted to small area of body) or rash that occurs >72h after penicillin administration - should they be given penicillin
probably not allergic
do not withhold unnecessarily for serious infections
however bear in mind the possibility of an allergic reaction
other beta-lactam abx including cephalosporins can be used too
dose of pivmecillinam for acute uncomplicated cystitis
initially 400mg for 1 dose
then 200mg every 8 hours (TDS) for 8 tablets
total 10 tabs
(for body weight 40kg and above)
when pivmecillinam is used orally, it must only be used in pt with the following body weight
40kg and above
what are the 5 interactions of pivmecillinam
- vit k antagonists (warfarin, acecoumarol, phenindione - increased risk bleeding events/increased AC effect, monitor INR)
- valproate - avoid increased risk of adverse effects
- MTX - increased toxicity , monitor
pivmecillinam - directions for administration
- swallow whole with plenty of water during meals while sitting or standing
labels for pivmecillinam
take with or just after food, or a meal
take with a full glass of water
this route of administration is not recommended for benzylpenicillin sodium
intrathecal
are benzyl penicillin sodium and benzathine benzylpenicillin the same
BS is a short acting form of B and is not interchangeable with BB
6 common side effects for all penicillins
- diarrhoea
- thrombocytopenia
- hypersensitivity
- nausea
- vomiting
- skin reactions
contraindications for coamoxiclav (2)
- hx of co-amoxiclav associated jaundice or hepatic dysfunction
- hx penicillin-associated jaundice or hepatic dysfunction
why does benzylpencillin need to be given by injection
inactivated by gastric acid and absorption from the GIT is low
what is benzathine benzylpenicillin used for and what route
IM injection
early syphillis and late latent syphilis
which one is more active - penicillin V or benzylpenicillin sodium
penicillin V (phenoxmethylpenicillin)
why should penicillin v not be used for serious infections
absorption can be unpredictable and plasma concentrations variable
pen V - phenoxy
what is used for penicillin resistant staphylococci
fluclox , this is because it is not inactivated by penicillinase enzymes
what are the antipsuedomonal penicillins
piperacillin (only available in combo with beta lactamase inhibitor tazobactam)
ticarcillin (only available with clavulanic acid)
are piperacillin + tazobactam and ticaricillin + clavulanic acid active against MRSA
no
Pivmecillinam hydrochloride is hydrolysed to …….., which is the active drug.
mecillinam
Maculopapular rashes commonly occur with the following 2 drugs but are not usually related to true penicillin allergy
ampicillin
amoxicillin
Maculopapular rashes commonly occur with ampicillin (and amoxicillin) but are not usually related to true penicillin allergy. They almost always occur in pt with the following symptom………., therefore BS penicillins should not therefore be used for blind treatment of sore throat
glandular fever
this drug has to be taken on empty stomach because less than half the dose is absorbed when taken orally, and absorption is further decreased by presence of food in gut
ampicillin
antipseudomonal penicillins spectrum of activity
BS activity against gram positive and gram negative and anaerobes
not for MRSA
pevmecillinam spectrum of activity
many gram negative bacteria
not against P. aeruginosa or enterococci
name the broad spectrum penicillins
ampicillin
amoxicillin
antipseudomonal penicillins (T+C, P+T)
co-amox
temocillin
which one with food and which one on empty stomach
food: pivmecillinam
empty: phenoxy
what is pen V and pen G
pen g = benzylpenicillin
pen v = phenoxy
name the narrow spectrum pencillins
pen g = benzylpenicillin
pen v = phenoxy
fluclox
who is probably not allergic to penicillin, and therefore a penicillin should not be withheld unncesessarily for serious infections.
Individuals with a history of a minor rash (i.e. non-confluent, non-pruritic rash restricted to a small area of the body) or a rash that occurs more than 72 hours after penicillin administration are probably not allergic to penicillin
this drug is not inactivated by penicillinases (unlike benzylpenicillin) so if effective in infections caused by penicillin resistant staph, which is the sole indication for its use
fluclox
co amox is CI in the following 2 scenarios
History of co-amoxiclav-associated jaundice or hepatic dysfunction; history of penicillin-associated jaundice or hepatic dysfunction
Hepatitis is more common with co amox if …
male
elderly
