Skin nociceptive block with pramoxine delivery by subcutaneous injection in rats

Pharmacol Rep. 2018 Dec;70(6):1180-1184. doi: 10.1016/j.pharep.2018.09.001. Epub 2018 Sep 10.

Abstract

Background: Pramoxine has been shown to produce spinal anesthesia, while cutaneous analgesia (peripheral) of pramoxine is not established. The experimental goal was to examine cutaneous antinociception produced by a local anesthetic (LA) pramoxine and compare this result with that of another well-known LA lidocaine.

Methods: Cutaneous antinociception was evaluated by blockade of pinprick- induced cutaneous trunci muscle reflex (CTMR) on the skin of rat's back. After the dose-related curves were constructed, the quality and duration of drug's (lidocaine and pramoxine) cutaneous antinociception were compared.

Results: We showed that pramoxine, as well as lidocaine produced skin antinociception in a dose-related fashion. The relative potency (ED50 [50% effective dose] basis) was lidocaine (5.44 [4.67-6.35] μmol) greater than pramoxine (42.1 [38.8-45.7] μmol) (p < 0.01). On the basis of equianalgesic doses (ED75, ED50, and ED25), pramoxine caused equivalent duration of cutaneous antinociception to lidocaine.

Conclusions: These preclinical data indicated that pramoxine elicits skin antinociception dose-relatedly. Pramoxine exhibits a potency less than that of lidocaine while they have a comparable duration of skin antinociceptive action.

Keywords: Lidocaine; Pinpricks; Pramoxine; Skin antinociception; Subcutaneous injection.

MeSH terms

  • Administration, Cutaneous
  • Anesthesia, Local / methods
  • Anesthetics, Local / administration & dosage*
  • Animals
  • Dose-Response Relationship, Drug
  • Drug Delivery Systems / methods*
  • Injections, Subcutaneous
  • Male
  • Morpholines / administration & dosage*
  • Pain / drug therapy*
  • Pain / pathology
  • Pain Measurement / drug effects*
  • Pain Measurement / methods
  • Rats
  • Rats, Sprague-Dawley
  • Skin / drug effects*
  • Skin / pathology

Substances

  • Anesthetics, Local
  • Morpholines
  • pramoxine