Phmkntx- 20A Flashcards
Define number needed to treat.
- used to compare efficacy of 2 treatments
- it is the average # of patients who need to be treated for 1 additional patient to benefit
- the lower the NNT, the more effective the treatment
What is absolute risk reduction.
ARR= difference in treatment response between two treatment groups
Formula for NNT
NNT=1/ARR
What is number needed to harm
- compares the risk of adverse event between 2 treatments
- the average # of pts who need to be exposed to a risk factor for 1 additional pt to be harmed
- the higher the NNH, the safe the treatment
Name the 4 components of pharmacokinetics
- pharmaco (drug), kinetics (movement)
- AD ME
- Absorption
- Distribution
- Metabolism
- Elimination
Question about pt with GI upset on the exam is a clue about
-altered or decreased absorption
What do we need to remember about old people?
- the older we get, the drier we become
- very susceptible to lithium toxicity, and elevated alcohol levels
- more total body fat, less body water
- increased VOD lipophilic drugs therefore decreased peak serum levels
CYP450 enzyme system is the majority of which phase of metabolism
- PHASE I
- puts on a handle
What is the main goal of drug metabolism?
-get rid of the foreign material (drug)
What is the main goal of phase I metabolism
-to prepare drug for phase II metabolism
Name drugs that induce P450 system
- phenobarbital
- cigarette smoke
- St. John’s wort
- carbabmazepine
Name drugs that inhibit P450 system
- Fluoxetine
- Valproate (also inhibitor of phase II metabolism)
- Ketoconazole
Which P450 does Carbamazepine induce?
-3A4
Which drugs does Carbamazepine reduce (increase the metabolism of)
- carbamazepine (autoinduction)
- valproate
- haloperidol
- protease inhibitors
- OCPs
- midazolam
- vincristine
Other drugs that induce 3A4
-Phenytoin
Other drugs that inhibit 3A4
- Ketoconazole
- grapefruit
- erythromycin
- cimetidine
- nifedipine
- verapamil
Cigarette smoke effects on P450
-induces 1A2
What is known about rates of drug metabolism over the life span
-highest, super adult levels, between child and adolescent years, therefore children and adolescents my require higher doses of some meds compared to adults to achieve desired effects
Phase II metabolism is the same thing as
-CONJUGATION
Name the drugs that go directly to phase II metabolism
- lorazepam
- temazepam
- oxazepam
- Lamotrigine
What is the mechanism of the drug-drug interaction between valproic and lamotrigine
- valproic acid inhibits the UGT1A4 resulting in HIGHER LAMOTRIGINE LEVELS
- therefore, start Lamotrigine at half usual levels and take twice as long to tritrate
the effect of a low sodium diet on lithium levels
-will cause toxic lithium levels
