Related Experiment Video
Updated: Apr 21, 2026
07:29
Intravascular Delivery of Biologics to the Rat Kidney
Published on: September 1, 2016
8.3K
Onset of Analgesia in Rats (Rattus norvegicus) for Three Buprenorphine Formulations
Eden D Alamaw1, Kenzie E Schwartz1, Mingyun Zhang1
11Department of Comparative Medicine, Stanford University, Stanford, California; and.
Summary
Extended-release buprenorphine formulations did not provide rapid analgesia in rats, with onset times ranging from 45 to 180 minutes. Despite reaching therapeutic plasma levels early, clinical pain relief was delayed for all tested products.
Area of Science:
- Veterinary Pharmacology
- Pain Management in Laboratory Animals
Background:
- Extended-release buprenorphine is common in lab animal medicine.
- Its analgesic onset in rats is not well-established.
Purpose of the Study:
- To investigate the analgesic onset of three extended-release buprenorphine formulations in rats.
- To compare the time to analgesia across different formulations.
Main Methods:
- Sprague-Dawley rats received saline, Bup-ER, Ethiqa-XR, or LAT-Bup.
- Thermal sensitivity was measured using a hot plate test at various time points.
- Buprenorphine plasma levels were analyzed.
Main Results:
- Bup-ER showed analgesia at 45 minutes, LAT-Bup at 120 minutes, and Ethiqa-XR at 180 minutes.
- Bup-ER and LAT-Bup reached therapeutic plasma levels by 5 minutes; Ethiqa-XR reached it by 45 minutes.
- No significant differences were observed between sexes.
Conclusions:
- None of the tested extended-release buprenorphine formulations provided analgesia within 5 minutes in rats.
- The clinical onset of analgesia varied significantly among the formulations, despite early achievement of therapeutic plasma concentrations.
Related Concept Videos
01:15Opioid Analgesics: Synthetic and Semisynthetic Opioids
1.5K
Synthetic and semisynthetic opioids are pivotal in pain management and tackling opioid addiction. Semisynthetic opioids, including morphinans (morphine derivatives), oxycodone, oxymorphone, hydrocodone, and hydromorphone, have improved pharmacokinetic profiles compared to morphine. Additionally, heroin and 6-MAM (6-Monoacetylmorphine) show better CNS penetration than morphine due to heightened lipid solubility. Hydromorphone, a potent opioid, undergoes hepatic metabolism to form the active...
1.5K
01:25Analgesia and Pain Management
3.3K
Pain is critical to various clinical pathologies, provoking an urgent need for effective management. Pain, whether acute or chronic, is a complex neurochemical process. Its alleviation depends on the type, with nonopioid analgesics effective for mild to moderate pain, such as musculoskeletal or inflammatory pain, while neuropathic pain responds best to anticonvulsants, tricyclic antidepressants, or serotonin/norepinephrine reuptake inhibitors. For severe acute or chronic pain, opioids may be...
3.3K
01:20Opioid Analgesics: Morphine and Other Natural Cogeners
1.7K
Opioids are a class of drugs that mimic endogenous opioid peptides and act on opioid receptors, and help in pain relief. These compounds are classified as natural, synthetic, or semi-synthetic. Natural opioids, like morphine, codeine, and thebaine, are derived from the opium poppy plant (Papaver somniferum or Papaver album) and are termed opiates. Synthetic opioids are artificial, while semi-synthetic opioids combine natural and synthetic compounds. Morphine, a prototypical opioid, possesses a...
1.7K
01:22Opioid Receptors: Overview
7.2K
Opioid receptors, including the mu (μ, MOR), delta (δ, DOR), and kappa (κ, KOR) types, belong to the rhodopsin family of G protein-coupled receptors. These receptors are located throughout the central and peripheral nervous systems and in non-neuronal tissues such as macrophages and astrocytes. Opioid receptor ligands can be categorized into agonists or antagonists. Highly selective agonists include [d-Ala2, MePhe4, Gly(ol)5]-enkephalin or DAMGO for MOR, [D-Pen2,...
7.2K
01:26Oral Drug Delivery Systems: Continuous-Release Systems
273
Continuous-release drug delivery systems offer a strategic approach to maintaining therapeutic drug levels over extended periods following oral administration. By modulating the release rate of active pharmaceutical ingredients, these systems minimize fluctuations in plasma concentrations, which enhances clinical efficacy and reduces the need for frequent dosing. Such characteristics make them particularly advantageous in managing chronic diseases where patient adherence and stable drug...
273