- Need to know half-life so that you won't over-dosing your patient. This is bc a drug w/ a long half-life will build up to toxic level if you keep giving too much too frequent. However, a drug with a short half-life needs to be given more frequent.
-Lithium half life 24 hrs, given once a day; => pt misses a dose; take 2 pills? no! problem? no!
-All drugs reach steady state in 3-5 half life's.
-If a drug has 2hr half life, how many half life does it take to go to 1/4? => 2 half life
-half life amount: 1/2 (1hl), 1/4 (2hl), 1/8 (3hl), 1/16 (4hl), 1/32 (5hl), 1/64 (6hl), 1/128 (7hl)
-if a drug has 1hr half life, pt misses the dose, frequency is every 6 hrs, => doesn't mean u should double the dose => it just tells you that you'd better not miss it. Probably good for ICU, probably not for home use.
- You don't want to check the level until it reaches until it reaches the steady state.
- You also don't want to change the dose until it reaches the steady state. Ex: Felbamate for anti-epileptics.
- Half life for Claritin is 8-11hrs (http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20C)/CLARITIN.html
) => Patient: I need to go to my parent's house and they have a dog and I'm allergic to dogs. I took the Claritin the day I go to my parents and it didn't work => NP: you need to take Claritin 3-5 days before you go to your parents to make sure it works.
Case: ICU pt 240BP=> long half life med such as amlodipine - calcium channel blocker med which has 30-50 half life (but good for inpatient)? No, IV fast and short half life => give every hr so it's at steady state very quickly. Reach steady state pretty quickly => ideal BP. Too much meds, very sensitive pt => goes down too low => stop BP meds => how long does it take for the pt to get out of the system => takes more than 3-5 half life to go back.
Case: 24mg Amlodipine for 80y/o in regular hospital floor from 200mmHg down to 70mmHg bc it's good for outpatient use => terrible drug for ER since it takes a long time to get rid of from the body since it's takes so long => do NOT use long half life but good for short half life drug.
~Miss Student
-Lithium half life 24 hrs, given once a day; => pt misses a dose; take 2 pills? no! problem? no!
-All drugs reach steady state in 3-5 half life's.
-If a drug has 2hr half life, how many half life does it take to go to 1/4? => 2 half life
-half life amount: 1/2 (1hl), 1/4 (2hl), 1/8 (3hl), 1/16 (4hl), 1/32 (5hl), 1/64 (6hl), 1/128 (7hl)
-if a drug has 1hr half life, pt misses the dose, frequency is every 6 hrs, => doesn't mean u should double the dose => it just tells you that you'd better not miss it. Probably good for ICU, probably not for home use.
- You don't want to check the level until it reaches until it reaches the steady state.
- You also don't want to change the dose until it reaches the steady state. Ex: Felbamate for anti-epileptics.
- Half life for Claritin is 8-11hrs (http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20C)/CLARITIN.html
) => Patient: I need to go to my parent's house and they have a dog and I'm allergic to dogs. I took the Claritin the day I go to my parents and it didn't work => NP: you need to take Claritin 3-5 days before you go to your parents to make sure it works.
Case: ICU pt 240BP=> long half life med such as amlodipine - calcium channel blocker med which has 30-50 half life (but good for inpatient)? No, IV fast and short half life => give every hr so it's at steady state very quickly. Reach steady state pretty quickly => ideal BP. Too much meds, very sensitive pt => goes down too low => stop BP meds => how long does it take for the pt to get out of the system => takes more than 3-5 half life to go back.
Case: 24mg Amlodipine for 80y/o in regular hospital floor from 200mmHg down to 70mmHg bc it's good for outpatient use => terrible drug for ER since it takes a long time to get rid of from the body since it's takes so long => do NOT use long half life but good for short half life drug.
~Miss Student
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