RESUMO
Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the best therapeutic options to treat pain. Their use in combination with other drugs may broaden their applicability in analgesia if their ceiling and adverse effects are reduced. The aim of this study was to evaluate the pharmacological interaction of two NSAIDs, paracetamol and meloxicam, with the antipsychotic drug risperidone in mice, in several experimental tests of nociceptive and inflammatory pain. Antinociception was assessed by dose-response curves to paracetamol and meloxicam before and after the i.p. administration of 0.5 mg/kg of risperidone. Results are presented as means ± SEM and differences were calculated by one-way ANOVA followed by Tukey's post-test. Paracetamol and meloxicam produced a dose-related antinociceptive effect with diverse potencies. Risperidone increased the analgesia mediated by paracetamol and meloxicam only in the tonic tests that detected inflammatory pain. This suggests that COX inhibition is only a partial explanation of the increased analgesic potency of paracetamol and meloxicam since the effects of NSAIDs in the CNS are mediated by multiple mechanisms. These results indicate that the combination of risperidone with paracetamol or meloxicam could be a new and effective alternative for the management of inflammatory pain.
Assuntos
Acetaminofen , Analgesia , Acetaminofen/farmacologia , Animais , Anti-Inflamatórios não Esteroides/uso terapêutico , Meloxicam/farmacologia , Meloxicam/uso terapêutico , Camundongos , Dor/tratamento farmacológico , Risperidona/farmacologia , Risperidona/uso terapêuticoRESUMO
Nonsteroidal anti-inflammatory drugs (NSAIDs) possess as primary action mechanism the inhibition of cyclooxygenases (COX-1, COX-2, and COX-3), thus producing a decreasing prostaglandin synthesis. This study was designed to evaluate whether the antinociception induced by NSAIDs could be modulated by clomipramine or risperidone using a chemical model of inflammatory acute visceral pain, the abdominal acetic acid induced a writhing test in mice. Dose-response curves, intraperitoneal, or intrathecal for the antinociceptive activity displayed by ketoprofen, piroxicam, nimesulide, parecoxib, and paracetamol were analyzed in order to obtain the ED50 of each drug. Pretreatment of mice with either clomipramine or risperidone, increased antinociceptive potency of ketoprofen, piroxicam, nimesulide, parecoxib, and paracetamol, expressed by a decrease in the values of antinociceptive ED50. The results that were obtained are in line with those where the inhibition of COXs provides a justification for most of the pharmacological actions. Nevertheless, several findings suggest other molecular mechanisms, among which may be mentioned, L-selecting shedding; inhibition of i-NOS; inhibition of NF-Kappa B; suppression metaloproteinasas; inhibition of ß2 integrin activation; activation of α2 -adrenoceptor; increase of IL-1ß; upregulation IL-6. In conclusion, the data generated in this study demonstrated that risperidone and clomipramine, separately, increase antinociceptive potency of NSAIDs in a chemical model of inflammatory acute visceral tonic pain.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Clomipramina/uso terapêutico , Risperidona/uso terapêutico , Dor Visceral/tratamento farmacológico , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Clomipramina/administração & dosagem , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Injeções Intraperitoneais , Injeções Espinhais , Masculino , Camundongos Endogâmicos , Medição da Dor , Risperidona/administração & dosagemRESUMO
BACKGROUND: Levetiracetam (LEV) is a novel anticonvulsant with proven antinociceptive properties. However, the antinociceptive and pronociceptive effect of this drug has not yet been fully elucidated in a tonic pain model. METHODS: Thirty-six male rats (Wistar) were randomized into six groups and underwent the formalin test as follows: rats in the control group were administered 50µL of 1% formalin in the paw; sham-group rats were administered 50µL of saline in the paw to mimick the application of formalin; the four experimental groups were administered LEV intragastrically (ig) (50, 100, 200 and 300mg/kg), and 40min later 50µL of 1% formalin was injected in the paw. RESULTS: LEV exhibited antinociceptive effect in the 300mg/kg LEV group (p<0.05) and a pronociceptive effect in the 100mg/kg LEV group (p<0.05) and in the 50mg/kg LEV group (p<0.001). CONCLUSIONS: The antinociceptive and pronociceptive effect of LEV in a tonic pain model is dose-dependent.