Pharm_Narcotic Analgesics Flashcards
Elderly patients usually require a ____ dose to achieve effective pain relief than younger patients.
Elderly patients usually require a lower dose to achieve effective pain relief than younger patients.
Neuropathic pain (spine to brain) usually requires ____ opioid doses than nociceptive pain.
Neuropathic pain (spine to brain) usually requires higher opioid doses than nociceptive pain.
’ _ _ _ _ _’ doses are usually required for continuous maintenance of pain relief than administration in response to recurrence of pain.
Lower doses are usually required for continuous maintenance of pain relief than administration in response to recurrence of pain.
What are the three major opioid receptor types?
µ (Mu)
δ (Delta)
κ (Kappa)
Dosing considerations for Opioid Analgesics
- Patients on Chronic Pain
For some patients with chronic pain, opioids do not exert an appreciable analgesic effect until a threshold dose has been achieved.
Dosing considerations for Opioid Analgesics
- Opioid Naive patients
Opioid analgesics should be started at a low dose and carefully titrated until an adequate level of analgesia is obtained, or until persistent and unacceptable side effects warrant a re-evaluation of therapy.
What does it imply if partial analgesia with incremental dosing in opioid-naive patient fails to achieve its therapeutic effect?
Failure of at least partial analgesia with incremental dosing in the opioid-naive patient may indicate that the pain syndrome is unresponsive to opioid therapy
What are the clinical uses of opioid agonists?
- List drug class & examples
Analgesia:
Codeine, morphine, pethidine
Anaesthetic adjuvant:
Fentanyl
Cough suppressant / antitussive: Codeine
Anti-diarrhoeal:
Diphenoxylate
What is the most important reason why Opioids should be avoided in infants?
Respiratory Depression (RD)
It Should not occur at normal therapeutic doses but can be lethal in:
1) Overdose (OD)
2) Respiratory disease (RD)
3) hepatic dysfunction
4) Combination with other CNS depressants
5) Young children
What are the common adverse effects of Narcotic Analgesics (Opioids)?
- N&V
- Drowsiness
- Constipation (reduced GI motility)
Nausea / vomiting most probably due to actions on the chemoreceptor trigger zone in the area postrema of the medulla (usually reduces with repeated or chronic use).
What are the common adverse effects of Narcotic Analgesics (Opioids)
Overdose?
M.U.M.
1) Miosis (pinpoint pupils) will be present for a patient that just collapse due to drug OD.
However, Miosis may no longer be present due to a drug OD, for e.g. patient collapsed due to drug OD 30mins to 1 hr ago.
2) **Mydriasis **(pupils remains dilated regardless of light in the environment)
3) Urinary Retention due to increased bladder sphincter tone (esp. patients with prostatic hypertrophy)
4) Postural hypotension & Bradycardia
5) Immunosuppressant effect with long-term use
6) Trigger Histamine release from mast cells:
- urticaria and itching
- bronchoconstriction
- hypotension due to vasodilatation
List some of the commonly used Opioid Antagonists
Opioids themself are agonist, we need antagonist to reverse the OD.
Naloxone (IV) / Naltrexone (PO) / Nalmefene (IV)
Strong µ (Mu) antagonism;
also δ (Delta) & κ (Kappa) antagonism.
When do we require the use of Opioid Antagonists?
For drug overdose (OD), to reverse drug OVERDOSE.
What is the main difference between drug toxicity vs drug overdose?
**Drug overdose: **
Over-consumption over a short period of time.
**Drug toxicity: **
Chronic usage
Route of administration and duration of action for Opioid Antagonists.
Naloxone / Naltrexone / Nalmefene
Naloxone (IV) / Naltrexone (PO) / Nalmefene (IV)
Naloxone is short-acting (usually IV)
Naltrexone is long-acting (PO)
Nalmefene is long-acting (IV)(new)
Used to counteract opioid overdose & toxicity
- Nalmefene replaced the use of Naloxone and Naltrexone
Recall why are these drugs used again?
