Principle 1: Do they need the medication?
- People are on too many medications
- You can’t overdose on something you don’t have
- The present predicts the future
Dont restart them
Move to limit med use where it’s not needed
Principle 2: Risk vs Benefit
Cardiotox - esc or citalopram
- QT prolongation
- Need to check QTc
Need to show they can control bg on their own
Pt disposition
- Are they oging home?
- Staying in ICU
- Going to psych unit?
Diff levels of monitoring needed for these
Risk to nursing staff? Risk to themselves if dont restart med?
ADHD meds - cant forget about the benefits of meds it might help the person be less agitated
Principle 3: Kinetics and Dynamics (Pharmaco,
Toxico)
The 5 Half Lives rule: Useful (to a point)
* From steady state:
* 97% of drug eliminated in 5 half lives
* 99.9% in 10 half lives
* Most patients recover from drug overdose in 1-4 days
* Important Considerations
* Active metabolites
* Genetic variations in CYP enzymes
* Saturation of enzymes
* Changes in physiologic milieu
How many half lives are we at
Take care of pt and ABC, the body iwll do the rest of eliminating the drugs
Usually recover 1-4 days
There are exceptions
Imipramine -
- Metabolized by 2D6
○ Poor, rapid metabolizers
- Desimipramine active metabolite
- Can saturate metabolism
Change blood or urine pH can affect drug elimination
Most important caveat
Toxicokinetics not equal
Pharmacokinetics
Absopriton is diff if you take many tablets of something or 2
Slow gastric emptying, slow gut w anticholinergic fx
Extendered release pdts - dont get absorbed right away
Clozapine elimination
Long elimination pattern already
80 hours in some cases
In OD even more prolonged
Can be due to antichoinergic protperties
Plateau of 25 h, drug abs is slowed down, ongoing absorption taking place
Elim process dragged out
Principles 4: Is the patient in
withdrawal/experiencing discontinuation
syndrome?
- Most likely culprits:
- SSRIs
- SNRIs
- Baclofen
- Opiates
- Benzodiazepines
- Ethanol
- Beta-blockers
- Clonidine
- Is your Antidepressant Patient
FINISHED?
Flu like symptoms
Insomnia
Nausea
Imbalance
Sensory Disturbances
Hyperarousal (Agitation/Anxiety)
Baclofen withdrawal is a thing, right?
Yes. Yes, it is.
Onset: 24-48hours
Common Scenarios:
◦Intrathecal Pump interruption/failure
◦After overdose, failure to restart
◦Can happen with dose adjustment
GABA-B Withdrawal looks like GABA-A
Withdrawal
Agitation
Confusion
Hallucinations
Autonomic volatility
Tremors
Treatment:
Restart at previous dose
(Or lower and titrate to
effect)
Benzodiazepines
Principle 5: Is there a blood level that can be
done?
- Usually if a patient’s levels are in therapeutic range they can be
restarted on their medication. - Considerations:
- Where predictable elimination kinetics exist
- Plasma levels associated with toxicity are poorly established for most drugs
- Toxicity can occur below the therapeutic range
- Very few drugs have Therapeutic Drug Monitoring order sets
- Never order a lab just to do a test
Principle 6: Is a drug interaction likely?
What have we given to the patient to treat their poisoning?
* Is this drug or poison one of the “usual suspects” for drug
interactions?
* Are we switching medication?
* Some antidepressants have washout periods that are needed
Principle 7: Implementation and Minimizing
Risk
- Start low, go slow
- Restart the most clinically important drug first
- If multiple drugs are important – restart the drug with the shortest
half life first
