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CASE 111 (23/7/2020) - Coggle Diagram
CASE 111 (23/7/2020)
Phenytoin
Half life : 22 hours
management of phenytoin overdose
gastric lavage
Monitor level every 4 hrs until completely decline before start new dose
activated charcoal
side effect
Gingival hyperplasia
ataxia
hirsutism
headache
nausea & vomitting
Education
Advise pt not to discontinue phenytoin without consultation
Educate pt on side effects
monitoring
liver function test
suicidality
full blood count
interaction of phenytoin with other medication
Phenytoin is CYP3A4 and CYP2C9 inducer while Atorvastatin, Bisoprolol and Amlodipine metabolised by CYP3A4
Take Phenytoin with Atorvastatin Amlodipine and Bisoprolol
treatment options
Consider an alternative for one of the interacting drugs in order to avoid therapeutic failure of the substrate
Frequent monitoring and dose adjustment.
Consider in avoiding concomitant use of phenytoin and other interacting drug
treatment plan.
Discontinue tablet phenytoin
Start T. Levetiracetam 500mg BD.
education
Educate patient on side effect of levetiracetam
Emphasize on how to consume T. Levetiracetam
drug interaction between phenytoin and warfarin
Used of warfarin & phenytoin together may increase risk of bleeding.
Phenytoin can lead to increases or decreases in the INR. Upon initiation of phenytoin, the INR may increase due to the displacement of warfarin from protein binding sites. Long-term phenytoin use with warfarin can lead to a decrease in the INR since it is a CYP inducer.
Phenytoin may increase warfarin metabolism, thus reduce effect of warfarin.
Phenytoin is enzyme inducer of the CYP3A4 and CYP2C9 families of the P450 enzyme which responsible for the liver’s degradation of various drugs.
Why Atorvastatin can be prescribed anytime not only at night ?
But the longer half-lives of rosuvastatin, atorvastatin, pitavastatin, and pravastatin has longer half-lives allow these agents to maintain a therapeutic drug concentration over a 24-hour period and allow alternate administration times
Simvastatin, fluvastatin, and lovastatin have a short elimination half-life compared to other drugs within the class. Agents with significantly shorter elimination half-lives require bedtime dosing to maximize efficacy - allowing the greatest statin concentration to be present while endogenous cholesterol synthesis is the highest.
They act by inhibiting the enzyme HMG CoA reductase, which controls synthesis of cholesterol in the liver. Most manufacturers of statins recommend that they are taken at night, on the basis of physiological studies which show that most cholesterol is synthesised when dietary intake is at its lowest.