Professors Key Facts Flashcards
Elderly patients have a high incidence of drug interactions due to the likelihood of _____________________
Polypharmacy
Intrinsic factors in pharmacokinetic differences in systemic exposure are a result in changes in:
Age (pediatric, young adults, elderly) Gender Race Weight (obesity) Height Disease Genetic polymorphism Organ impairment (renal & hepatic) Pregnancy Pathophysiologic conditions
Extrinsic factors in pharmacokinetic differences in systemic exposure are a result in changes in:
Use of other drugs (interactions)
Tobacco
Alcohol
Food habits (ie. grapefruit juice)
Short-acting benzodiazepines, such as Midazolam, may be used for:
Acute episode of delirium Seizure disorders Alcohol withdrawal Benzodiazepine withdrawal Severe generalized anxiety disorder Pre-procedural anesthesia End-of-life care
Benzodiazepine use will increase the risk of:
Cognitive impairment
Falls
Accidents (MVA)
Fractures in older patients
First-pass effect or first-pass metabolism
When swallowed, a drug is absorbed by the digestive system and enters the hepatic portal system. It is carried through the portal vein into the liver where it undergoes liver metabolism before it reaches the systemic circulation.
Alternative routes of drug administration that can avoid first-pass metabolism are intravenous, intramuscular, sublingual, suppository, and inhalational aerosol. These medications allow drugs to be absorbed directly into the systemic circulation
Drugs that have a high first pass effect
Nitroglycerin
Lidocaine
Morphine
The principal factors that determine the actual applications of a particular benzodiazepine are:
- The pharmacokinetic properties of the drug itself
2. Research & marketing decisions of pharmaceutical companies
Long-Acting Benzodiazepines
Diazepam (Valium)
Temazepam (Restoril)
Clonazepam (Klonopin)
Chlordiazepoxide (Librium)
Medium-Acting Benzodiazepines
Alprazolam (Xanax)
Lorazepam (Ativan)
Short/Fast-acting Benzodiazepines
Midazolam (Versed) IV
Triazolam (Halicon)
Contraindications for Benzodiazepine use in the elderly
Falls & fractures Unsteadiness Confusion Short-term cognitive defects Dizziness
Drug distribution in neonates
Protein binding is decreased in the neonate. The amount of serum albumin is relatively lower than adults and have decreased binding affinity for many drugs. Bilirubin and free fatty acids are present in higher concentrations in neonates and compete with some drugs that bind to albumin.
The reduced plasma protein binding of drugs results in a larger fraction of free drug in neonatal serum and greater drug effect. Serum albumin concentrations do not reach adult levels until 10 months to 1 year of age
Drug metabolism in neonates
Full-term infants have a slower hepatic drug metabolism as compared to children 1 year and older. By age 1, children metabolize drugs faster than adults. However, this increase in metabolism slows to adult levels around the second year of birth as the children go through puberty into adulthood.
Acetaminophen overdose & antidote
APAP overdose is medical emergency. Early diagnosis and treatment are necessary for a positive patient outcome.
Acetylcysteine is the antidote, best given within 8-10 hours of overdose or as soon as possible after injection. May be administered orally or intravenously.
Acetylcysteine
APAP antidote
Acetadote 200 mg/ml vial diluted in 5% dextrose solution.
Given in 3 dosages:
150 mg/kg IV infusion over 15 min to 1 hour (1 hour is preferred to decrease rare adverse effects of rash, itching, angioedema, bronchospasm, and hypotension)
2nd dose infused over 4 hours at rate of 50 mg/kg.
Last dose over 16 hours at 100 mg/kg
Naloxone
Opioid antagonist for opioid overdose
Can be given IV, IM, SQ, or intranasal route.
Has a shorter half-life than morphine, so doses of Naloxone may be repeated at 2-3 minute intervals until results are effective.
In an emergency, Naloxone IV 0.4 mg for adults, the dosage is titrated to prevent withdrawal.
Naloxone is a mu-receptor antagonist. IV is the preferred method to reverse opiate effects of respiratory and CNS depression
Naltrexone (Vivitrol)
Naltrexone (Vivitrol) IM 380 mg is administered every 4 weeks, so it would remain in the patient’s system and have a longer duration of action compared to the oral formulation.
Naltrexone mimics the action of naturally occurring opiate neurotransmitters in the brain by acting as an opioid receptor antagonist.
The administration should be delayed between 7-10 days after the last use of opiates until there are no opiates left in the patient’s system.
Common SE: Injection site reactions (IM), depression, suicidal ideation, sedation, and nausea. Hepatocellular injury is rare but serious side effect that can occur at a higher dose, but this is usually reversed after the medication is discontinued.
