Parkinson's Drugs
Why is levodopa used instead of dopamine for treating Parkinson's disease?
Dopamine cannot cross the blood-brain barrier, but levodopa can
What is the primary mechanism of action of phenytoin?
Blocks voltage-gated sodium channels to stabilize neuronal membranes
What is the most serious adverse effect of morphine?
Respiratory depression
What is the mechanism of action of alprazolam?
Enhances GABA activity by binding to GABA-A receptors
What is the mechanism of action of SSRIs like fluoxetine?
Selectively inhibits serotonin reuptake in the synaptic cleft
Why is carbidopa combined with levodopa?
To prevent peripheral conversion of levodopa to dopamine, allowing more to reach the brain
Why is valproic acid absolutely contraindicated in pregnancy?
Category X - high risk of neural tube defects (spina bifida)
How does naloxone work to reverse opioid overdose?
Competitively blocks opioid receptors, reversing opioid effects
What is the most serious risk when combining benzodiazepines with alcohol or opioids?
Severe CNS and respiratory depression
How long does it typically take for SSRIs to show therapeutic effects?
4 to 6 weeks
What enzyme does selegiline inhibit, and why is this beneficial in Parkinson's disease?
MAO-B; prevents dopamine breakdown in the brain, prolonging its action
What does 'zero-order kinetics' mean for phenytoin dosing and monitoring?
Small dose increases can lead to disproportionate increases in serum levels; frequent monitoring is essential
Why might naloxone need to be administered multiple times after reversing an opioid overdose?
Naloxone has a shorter half-life than most opioids; effects may wear off before the opioid is eliminated
Why is phenobarbital a concern regarding drug interactions?
It is a potent hepatic enzyme inducer, decreasing levels of many other drugs
What serious adverse effect can occur when combining MAO inhibitors with tyramine-rich foods?
Hypertensive crisis
A patient on levodopa should avoid taking the medication with what type of food, and why?
High-protein meals; they compete with levodopa for absorption via amino acid transporters
Name TWO serious adverse effects that require monitoring with valproic acid.
Hepatotoxicity (monitor LFTs)
Thrombocytopenia (monitor platelet count)
Pancreatitis (sever abdominal pain, N/V)
Teatogenicity (spina bifida)
What adverse effects should you anticipate after administering naloxone to reverse opioid toxicity?
Acute withdrawal symptoms and return of severe pain
What must be assessed before discontinuing long-term alprazolam therapy?
Risk of withdrawal seizures; medication must be tapered gradually
Why are tricyclic antidepressants NOT first-line agents for depression?
Significant anticholinergic, antihistaminic, and cardiovascular side effects
A patient on Selegiline should avoid taking the medication with what type of food, and why?
Tyramine-rich foods (cheese, wine) beause it can cause hypertensive crises
A patient on haloperidol develops high fever (104°F), severe muscle rigidity, and altered mental status. What is happening?
Neuroleptic Malignant Syndrome (NMS) - life-threatening emergency; discontinue drug immediately
What are the nursing responsibilities when setting up a Patient Controlled Analgesia (PCA)?
Medications rights and verifying them with another RN
What is the antidote for Alprazolam and what should the nurse monitor for?
Flumazenil
Must be used carefully — carries risk of causing seizures
A patient on lithium presents with nausea, vomiting, tremor, and muscle weakness. What do you suspect and what should you do?
Suspect lithium toxicity; check lithium level immediately and hold medication