Opioid Analgesics Flashcards
Opioid Agonists
Work and activate receptors in the brain (mu and kappa)
Tolerance: requires larger dose to get same response.
Develops: analgesia, euphoria, sedation, respiratory depression
Doesn’t develop: constipation, miosos
Opioid analgesics
Act as agonists or antagonists at opioid receptors in the brain
Used for pain; pain is treated in the brain
3 types of analgesics
3 receptors
Mu: physical dependent, low GI sexretions, euphoria, respiratory depression, pain relief
Kappa: low GI motility, sedation, pain relief
Delta
Opioid Agonist
Adverse Effects
Respiratory depression Intracranial pressure Sedation Euphoria Miosos Constipation * low cough reflex Orthostatic hypotension Urinary retention
Opioid Agonist
-Tolerance
Develop: pain relief, euphoria, sedation, respiratory depression
Doesn’t: miosos, constipation
- cross tolerance: to other opioids, may not be complete Can be fatal.
Reduce dose by 25-50% 30-60% to be safe.
Physical dependence
-all opioids
Concern with chronic use (more than 2 weeks)
Yawning runny nose -anorexia tremor-sneezing weakness N/V symptoms of chronic use
Gradual withdrawal over 3-7 days minimizes these reactions
Morphine* Oxycodone (OxyContin) * Hydrocodone Hydromorphine Codeine * Meperidine Methadone* Dihydrocodeine Opium Nalbuphine Tapentadol* Levorphanol Tramadol * Paregoric *fetynyl, sufentinyl, alfentanil, remifentanil
Opioid receptor Agonists
Mixed opioid agonist-antagonists
Turns on some receptors and blocks others: gives good effects and minimizes others.
- Low potential for abuse & resp depression
- analgesic ceiling- only so much pain relief
- can cause withdrawal response in ppl who have used opioids
Mixed opioid agonist antagonist
Adverse effects
Psychomimetic effects: hallucinations, dysphoria
Concern with chronic use
Low respiratory depression
Pentazocine
Butorphanol
Buprenorphine (butrans)
-suboxone
Mixed opioid agonist antagonists
Naloxone
Naltrexone
Methylnaltrexone
Alvimopan
Opioid receptor antagonists
Opioid antagonists
Prevents receptors from being activated/turned on
Bumps the agonist off the receptor
*prevents drug from being activate
* prevents drug from being abused; due to absorption in GI tract
Opioid antagonists
Use
1-overdose/abuse detterant
-naltrexone
-naloxone 0% bioavailablity, only works if taken orally
* snorting or injection led to 100% withdrawal (no first pass)
2-treatment of opioid constipation: restore bowel function
-methylnaltroxone
-naloxegal
* ding cross BBB Bind to receptor jn gut
3- post op Ileus
-alvimopan
Morphine
- opioid agonist (C-2 drug)
- high first pass metabolism:variable ab, low oral bioavailablity
- active metabolite: M3G may cause neurotoxicity-increase renal impairment
- old patients need low doses
Oxycodone (OxyContin)
Opioid agonist
- resembles euphoria of heroine
- high bioavailablity, better CNS penetration
- “contin”: continual release
Hydromorphone
Opioid agonist
- more potent, fewer side effects
- active metabolite (H3G)- can contribute to neurotoxicity if renal function is impaired
Codeine
Opioid agonist
-terrible, doesn’t work
-more nausea and constipation
-* liver turns some of drug into morphine ( pro drug for morphine)
-* enzyme CYP2D6- genetically variable
Test for gene**
Activates more of the drug into morphine than a person without the enzyme
Tapentadol & tramadol have risk of causing?
Serotonin syndrome
Merperidine
Opioid agonist
Can Inhibit serotonin reuptake, short half life (3-4 hrs)
Toxic metabolite (tremor, rigidity, seizures, eliminated renally)
Lots of drug interactions: MAOIs: excitation, delerium, convulsions
Limited clinical role: rigors
Fetynyl, alfentanil, sufentinyl, remifentanil
Opioid agonist
Rapid onset, short duration
Synthetic, highly potent opioids ( anesthesia, limited role)
-IV, IM, transdermal patch, transmucosal
-used for hospitalized patients
Methadone
Opioid agonist Several unique actions -NMDA antagonist -**agonist at mu, kappa and delta receptor: inhibition of NE and 5-HT reuptake - long half life (12-190 hrs) -long duration with repeated dose - difficult to titrate
Buprenorphine (Buprenex, butrans, subutex)
- suboxone*
- Buprenorphine + naloxone
- sublingual tablet or film
- mixed opioid receptor agonist/antagonist
- special role in treating opioid dependence and managing withdrawal
- Lower risk of resp depression, more easily obtained than methadone
Tapentadol ( Nucynta)
Opioid agonist
Dual mechanism of action
- weak mu receptor agonist
- inhibition of NE and 5-HT reuptake
- SS
- AEs similiar to opioids
- increase risk of seizure
- may have high effects vs neuropathic pain
Tramadol (ultram)
Similar but less potent opioid effects
*serotonin syndrome
