Opiate Analgesic

Level 1

Tertiary amine which is a synthetic phenylpiperidine derivative

1. to provide the analgesic component in general anaesthesia
2. in combination with a major tranquillizer to produce neuroleptanalgesia
3. to provide analgesia during labour when regional anaesthesia is not in
use
4. as an agent used for patient-controlled analgesia
5. in premedication and
6. for palliative care

colourless solution 50mcg/ml, TDpatch (25mcg-100mcg/hr) and as lozenges

μ receptor agonist

Binds primarily to inhibitory G-Protein Coupled μ-opioid receptors→ ↑adenylyl cyclase→ ↓cAMP→ hyperpolarization of cell→↓neurotransmitter release

inhibitory action,
modulating the pain response to produce analgesia.

less likely to ppt histamine release
norad& serotonin axn, excitatory centrally

IV/IM/TD. BA PO 30%SL50%skin>90%
onset IM.: 7-8 mins; IV imm; TD 6 hrs
duration IM:1-2 hrs; IV:0.5-1hr; TD 12hrs

relative lipid sol 500

Rapid redistribution
pKa 8.4(10% union)

prot bind 80-85%

Mod Vd 4-6L/kg

Slow Hepatic, primarily via CYP3A4clearance

excretion Urine 75%

half life I.V.: 2-4 hours, prolonged context sensitive half time

- Incompatible with thiopental

- Dialysis - unknown

Bolus: 1-2 mcg/kg
inf: 1-2 mcg/kg/hr

(relative potency 50-100)

Similar to other opioids. Differences due to lipid sol.
Does not cause delayed respiratory depression because it rapidly diffuses into and out of the CSF. Raised CSHT prolonged infusion may lead to increased duration of action and SE

Similar. Differences due to lipid sol.
Does not cause delayed respiratory depression because it rapidly diffuses into and out of the CSF. Raised CSHT prolonged infusion may lead to increased duration of action and SE