Related Experiment Video
Updated: Sep 15, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
No development of tolerance to analgesia by repeated administration of H1 antagonists
C Ghelardini1, N Galeotti, A Bartolini
1Department of Pharmacology, University of Florence, Italy.
Abstract:
The effect produced by repeated administration of the H1-antihistaminics diphenhydramine, promethazine and pyrilamine on their ability to induce antinociception was evaluated in the mouse hot-plate and abdominal constriction tests. Contrary to morphine, baclofen and oxotremorine, the three H1 antagonists investigated did not promote the development of tolerance to the analgesic effect after 14 days of repeated treatment. H1 antagonists could, therefore, represent a promising pharmacological approach to the management of chronic pain.
Related Concept Videos
Combined Effects of Drugs: Antagonism
The most common type is receptor antagonism, where one drug acts as an antagonist to block the effects of another drug by...
Desensitization and Tachyphylaxis
Several...
Adrenergic Antagonists: Pharmacological Actions of ɑ-Receptor Blockers
α1-blockers: These drugs inhibit α1-adrenoceptors on smooth muscle cells, resulting in vasodilation. This vasodilation lowers blood pressure, making α1-blockers valuable in treating hypertension. Additionally, α1-blockers effectively address urinary obstruction...
Analgesia and Pain Management
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Acid Suppressive Drugs for Peptic Ulcer Disease: Histamine H2-Receptor Antagonists

