Drugs for pain Control Opioids_April 30 Flashcards
What is the difference between opioids and opiates?
- Opiate=drug derived from opium plant and synthetic derivatives (morphine, codeine, oxycodone)
- Opioid=All drugs with morphine like actions
Narcotic: morphine like strong analagesics
What are opioids used for in dentistry?
Acute pain
Which receptors do opioids work on?
mu (micro symbol) receptors
-Opioids such as morphine, codeine, oxycodone are agonists
Where are mu receptors found? What happens when they are activated?
- Primary afferent on dorsal horn of spinal cord
- Blocks calcium channels on primary afferents
- PRevents release of substance P
- Also opens potassium channels on secondary afferents
- Hyperpolarises neuron making it less excitable
What are the adverse effects of opioids?
-Respiratory depression (narrow therapeutic index)
- Sedation
- Nausea
- Miosis
- Euphoria
What are some advantages of opioids?
- Quick effect IV (peak in 10minutes), relief by 1hr orally
- Profound effect especially if not previously used on person
What forms do opioids come in in the dental setting?
- Solid
- Liquid
What is required in a prescription?
Pt name, date of birth, address
Name + strength + form + dose of drug
Quantity to be dispensed (in words and numbers)
How is morphine cleared?
- Hepatically
- Metabolites renally cleared
What is the half life of morphine?
2-4 hrs
What is the oral bioavailability of morphine?
25%
What dosage is used for morphine?
5-20mg depending on pain severity, decreased by 75% in elderly
How does codeine give its analgaesic effect?
Metabolised to morphine by CYP 2D6 enzyme
How does Tramadol give analgaesic effect?
- Metabolised by 2D6 enzyme to metabolite with high affinity to mu receptor
- Prevents reuptake of noradrenaline and serotonin to activate descending inhibitory pathway
What are the adverse reactions with tramadol?
Nausea
- Reacts with drugs with serotonin activitiy
- Increased INR with warfarin
