Comparison of pain response after subcutaneous injection of two maropitant formulations to beagle dogs

Abstract

The antiemetic maropitant, with metacresol as preservative (Cerenia, Zoetis), has been associated with pain after subcutaneous injection in dogs and cats. Recently, a generic formulation containing benzyl alcohol was authorised (Prevomax, Le Vet). Benzyl alcohol is reported to have local anaesthetic properties and reduce injection pain. This study compared local pain after subcutaneous injection of the two maropitant formulations, administered at approximately 4°C and 25°C, to dogs. Thirty-two healthy beagle dogs were enrolled into a blinded, randomised, cross-over study. Dogs received subcutaneous injections of maropitant injection containing metacresol as preservative and maropitant injection containing benzyl alcohol as preservative, both at approximately 4°C and 25°C, with at least three days in between treatments. Injection pain was evaluated by two blinded observers using a visual analogue scale immediately after injection and a simple descriptive scale at two minutes after injection. In healthy beagle dogs, subcutaneous injection of maropitant with benzyl alcohol is significantly less painful than injection of maropitant with metacresol.

A randomized trial: The safety, pharmacokinetics and preliminary pharmacodynamics of ropivacaine oil delivery depot in healthy subjects

“…Benzyl alcohol is a rapid analgesic for common injections. Benzyl benzoate has an antiinflammatory effect, and soybean oil is the main excipient for lipid emulsion for injection [34][35][36]. Therefore, RODD was judged to have better clinical safety and anesthetic effects.…”

Dilution of maropitant (Cerenia) in lactated Ringer solution prolongs subcutaneous drug absorption and reduces maximum plasma concentration

“…presentations of injection-associated pain. 1,9 The commonly used maropitant-containing product Cerenia requires refrigeration after puncture of the vial, 1 and refrigeration may help to reduce or eliminate injection site pain. 10 Other methods have also been suggested to reduce the pain of injection, including use of a different excipient (benzyl alcohol in lieu of the commercial formulation with metacresol) 9 and diluting maropitant in lactated Ringer injectable solution (LRS).…”

“…Pain scores were assessed according to a basic visual analog scale, as described by Deckers et al 9 A mild reaction (grade 1) included looking at the injection site, twitching skin, or licking and scratching. A moderate reaction (grade 2) included vocalization, jumping, or repeated licking and scratching.…”

“…Figure 2-Mean pain scores during and after SC administration of 1 mg/kg of Cerenia (Control) and the same dose of Cerenia diluted in 10 mL/kg of LRS in dogs (n = 5).Cerenia is a maropitant citrate-containing product formulated with sulphobutylether-β-cyclodextrin (Cerenia Injectable, 10 mg/mL). Pain was assessed on a visual analog scale as described by Deckers et al9 Scoring was conducted by 3 blinded reviewers at the time of treatment (0) and then 10, 20, 30, and 120 minutes after treatment. There were no significant between-group differences in pain scores.…”