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18 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Structure |
Phenanthrene 5 rings |
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Preparations |
Liquid Oral IV Intrathecal |
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Isomers |
Levorotatory is active isomer |
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Pka |
7.9 - weak base 23% unionised at phys pH |
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Lipid solubility Potency |
Poor relative potency - 1 |
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Pharmacokinetics - Absorption |
Oral availability variable ~30% ionised in stomach - therefore absorbed later Bioavailability ~ 25% as 7% taken up by lungs |
oral/bioavailability |
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Pharmacokinetics - Distribution |
PPB - 35% Vd - 3L/Kg |
PPB Vd |
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Pharmacokinetics - Metabolism |
Liver, **kidney 75% ⇒ M3G inactive 10% ⇒ M6G active (same duration, 13 x potency) 5% ⇒ demethylated to normorphine |
Location Metabolites and activity |
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Pharmacokinetics - Excretion |
Clearance 16ml/kg/min 90% renal 10% bile none unchanged. T𝜷1/2 = 2hrs |
Clearance rate Proportion renal/liver % unchanged. |
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Pharmacodynamics - Opioid receptor effects |
- Activation of opioid receptors - GPCR - Inhibit adenylate cyclase - decreased cAMP - Increase K conductance = hyperpolarise membrane - Block presynaptic ca channels = reduce nervous transmission. |
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Pharmacodynamics - CNS |
Analgesia - Visceral > m/skel Euphoria Miosis Decreased Cerebral BF Decreased ICP Sedation Euphoria |
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Pharmacodynamics - CVS |
Central vagal excitation = bradycardia Mildly negatively inotropic ↓ SVR secondary to histamine release. = ↓ in C.O. and MAP |
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Pharmacodynamics - Resp |
Due to agnoism at mu2 ↓RR and ↓MV TV can ↑ or ↓ ↓ of pontine and medullar ventilatory centres - shifts CO2 response to right, and can cause apnoea/pauses and periodic breathing Cough suppressant |
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Pharmacodynamics - GIT |
↓ motility and gastric emptying Risk of biliary/sphincter oddi spasm |
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Pharmacodynamics - Renal |
Reduced due to reduced CO |
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Obstetrics |
rapid placental transfer no affect on uterine tone |
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Side effects |
Nausea Pruritis Heaviness, warmth His release: |
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Interactions |
Cardiac effects worsened in combo with N20 or benzos MAOI = exaggerated CNS depression |
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