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P-gp is largely implicated in the brain-to-blood efflux of opioids, namely morphine and oxycodone. Long-term ex-posure to morphine and oxycodone has proven to up-regulate the expression of ABC transporters, such as P-gp, BCRP and MRPs, at the BBB, which may lead to increased tolerance to the antinociceptive effects of such drugs.
Oral administration of morphine will further act to slow this onset of action and reduce morphine’s bioavailability. Typically, 40–60% of orally ingested morphine will fail to reach the systemic circulation as a result of significant first-pass metabolism in the liver and gut wall.
With repeated dosing, morphine’s oral bioavailability ranges from 24% to 40%. 37,38 Morphine’s low bioavailability and relative hydrophilicity make it less than ideal as an analgesic. Because of the delay in transport across the blood-brain barrier, morphine has a slower onset of action than other opioids.
24 gru 2011 · In this review we will discuss recent advances in the field, considering brain disposition of M6G, UDP-glucoronosyltransferases (UGT) involved in morphine metabolism, UGT interindividual variability and transport proteins. Keywords: Blood-Brain-Barrier, Genetic variability, Morphine, Morphine-3-glucuronide, Morphine-6-glucuronide, Transport ...
1 lis 2021 · Brain edema and blood-brain barrier permeability was reduced by post-TBI morphine. Morphine treatment significantly decreased neuroinflammation. Naloxone pretreament effectively reversed all beneficial effects of morphine.
9 lip 2024 · Co-administration of morphine with the dual Hcrt receptor antagonist suvorexant prevents morphine-induced changes in the number and size of Hcrt neurons, the increase in Hcrt projections to the...
14 mar 2024 · Naloxone acts by competitive displacement of opioid agonists at the μ-opioid receptor (MOR). Its effect depends on pharmacological characteristics of the opioid agonist, such as dissociation rate from the MOR receptor and constitution of the victim.
