Centrifugation: When plasma is required, or when not using a serum gel separator tube, follow these instructions: 1  Draw 12 mL of whole blood for each 5 mL of serum or plasma needed. 2  Centrifuge for at least 15 minutes at 2200-2500 RPM. 3  Pipette the serum or plasma into a clean plastic screw-cap vial and attach the label.
Buccal administration; Naloxone; Naltrexone; opioid antagonist; Pharmacokinetics; First-pass metabolism Summary The opioid antagonists naloxone and naltrexone are both known to undergo extensive first-pass metabolism after oral dosing. The buccal route was investigated as a potential alternative to oral administration. Oral and buccal bioavailabilities of naloxone and naltrexone were determined in rats. Less than 1 % of oral naloxone or naltrexone was bioavailable, but buccal administration resulted in approximately 70% bioavailability for each drug.
Antagonist Pharmacotherapy. Naltrexone is an opioid antagonist that blocks the effects of heroin and most other opioids. It does not have addictive properties or produce physical dependence, and tolerance does not develop. It has a long half-life, and its therapeutic effects can last up to 3 days.Naltrexone is not a stigmatized treatment.he antagonist blocks the receptor and prevemts activation by neurotransmitters or other drugs. So in the case of opiates, lets look at the opiate agonist, morphine. When morphine enters the brain, it binds to opiate receptors and activates them. This binding is what produces the effects of Morphine.