Opioid Analgesics Flashcards
What are the acute effects of opioids on CVS, GIT and CNS?
CVS:
miosis (pupillary constriction except meperidine which causes dilation due to muscarinic blocking effect)
pruritis (histamine release)
gynecomastia (block DA)
SIADH (stimulate ADH release)
decreased GFR (decreased blood flow)
GIT:
constipation (relaxes longitudinal muscle and decreases peristalsis)
urinary retention (constricts circular muscle)
biliary colic (gall bladder attack, Oddi’s sphincter constriction, all but meperidine contraindicated in biliary spasm)
CNS:
analgesia (weakens sensory and emotion pain), sedation, euphoria
respiratory depression (decreased response to CO2 challenge in CNS)
increased ICP (contraindicated in head injury)
antitussive (suppresses cough)
emesis (induces vomiting)
Which among the effects of opioids will be always present in spite of long term use?
Marked tolerance occurs for all the effects of opioids, except miosis and constipation.
What are the clinical uses of morphine (mu receptor agonist)?
Analgesia (via IV), Preanesthetic medication and Intraoperative anesthesia (during surgery), managing acute pulmonary edema (via IV, reduces anxiety, preload, and afterload)
What are the important ADRs of morphine?
Respiratory depressant, physical dependence, vomiting, OD toxicity in renal failure, high doses may lead to coma
How do you treat opioid addiction?
The medicines used to treat opioid abuse and addiction are methadone, buprenorphine, and naltrexone.
What are the symptoms of opioid overdose and what is its management?
Triad of opiod OD: pinpoint pupil, respiratory depression, and coma; Ventilatory support given along with naloxone (promptly reverses Sx but duration only 1-2 h so need to repeat dose)
What are the advantages of Patient controlled analgesia (PCA)?
The patient controls a parenteral (IV) infusion device by pressing a button, a pre-programmed dose of desired opioid analgesic is delivered. Shown to have better pain control and less opioid requirement. Useful in post-op cases.
Which drugs cause serotonin syndrome?
Meperidine and dextromethorphan and tramadol should not be used with SSRIs or MAOI bc cause serotonin syndrome.
Which drugs precipitate withdrawal syndrome?
Mixed agonist - antagonists Nalbuphine, Pentazocine, butorphanol, and Buprenorphine all have the potential to precipitate abstinence symptoms in chronic opioid addicts as naloxone and naltrexone.
Why meperidine does not cause miosis and biliary colic?
Bc it has significant anti-muscaurinic effects so no miosis and biliary colic but tachycardia.
How do you diagnose opioid withdrawal in neonates and how do you treat?
Opioid abused mother’s newborn baby may have withdrawal symptoms shortly after delivery:
Irritability, Shrill crying, Diarrhea, and Seizure
Treatment: Diazepam,
Camphorated tincture of opium (oral), or
Methadone (oral)
What are the clinical uses and ADRs of codeine (moderate mu agonist)?
antitussive, high dose for analgesia; ADRs include drowsiness, lightheadedness, dizziness, sedation, shortness of breath, nausea, vomiting, sweating, and constipation
What are the clinical uses and ADRs of methadone (strong mu agonist)?
Long acting opioids used in management of opioid withdrawal state so used in maintenance programs for addicts bc use permits slow tapering effect and also diminishes the intensity of abstinence syndrome; The major hazards of methadone are respiratory depression and, to a lesser degree, systemic hypotension. Respiratory arrest, shock, cardiac arrest, and death have occurred.
What are the clinical uses and ADRs of Buprenorphine (mixed agonist-antagonist)?
Used for maintenance programs for addicts. use for depression and smoking cessation, toxicity = anxiety, insomnia, seizures. Remember shelf loves + contradicted in seizures and anorexia. ADRs include constipation, nausea, and vomiting.
What are the clinical uses and ADRs of Clonidine (α2 agonist)?
Cancel over-activity of sympathetic nerve system; ADRs include dry mouth, drowsiness, dizziness, constipation and sedation.
