Pharmacological interaction of α-bisabolol and diclofenac on nociception, inflammation, and gastric integrity in rats.

Preclinical Research & Development The combination of nonsteroidal anti-inflammatory drugs (NSAIDs) with herbal products having analgesic and anti-inflammatory effects may increase their beneficial effects and limit their side effects. In this study, the effects of an interaction between α-bisabolol and the NSAID, diclofenac on nociception (formalin test), inflammation (paw inflammation produced by carrageenan) and gastric injury in rat was assessed. Diclofenac, α-bisabolol, or diclofenac-α-bisabolol combinations produced antinociceptive and anti-inflammatory effects in rat (p < .05). The systemic administration of diclofenac, but not α-bisabolol, produced gastric damage while the diclofenac-α-bisabolol combinations produced limited gastric damage. Effective dose (ED40 ) values were determined for each individual drug and analyzed isobolographically. The theoretical ED40 values for the antinociceptive (98.89 mg/kg) and the anti-inflammatory (41.2 mg/kg) effects differed from the experimental ED40 values (antinociception: 38.7 mg/kg and anti-inflammation: 13.4 mg/kg). We concluded that the interactions between diclofenac and α-bisabolol are synergistic. These data suggest that the diclofenac-α-bisabolol combinations can interact to produce minor gastric damage, thereby offering a safer therapeutic alternative for the clinical management of inflammation and/or inflammatory pain.

Anti-inflammatory and utero-relaxant effect of α-bisabolol on the pregnant human uterus.

The aim of this study was to evaluate the in vitro anti-inflammatory and utero-relaxant effect of α-bisabolol on the pregnant human myometrium. Samples from the pregnant human myometrium were used in functional tests to evaluate the inhibitory effect of α-bisabolol (560, 860, 1,200 and 1,860 µM) on spontaneous myometrial contractions. The intracellular cyclic adenosine monophosphate (cAMP) levels generated in response to α-bisabolol in human myometrial homogenates were measured by ELISA. The anti-inflammatory effect of α-bisabolol was determined through the measurement of two pro-inflammatory cytokines, tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß, and the anti-inflammatory cytokine IL-10, in pregnant human myometrial explants stimulated with lipopolysaccharide (LPS). Forskolin was used as a positive control to evaluate the cAMP and cytokine levels. α-Bisabolol was found to induce a significant inhibition of spontaneous myometrial contractions at the highest concentration level (p<0.05). α-Bisabolol caused a concentration-dependent decrease in myometrial cAMP levels (p<0.05) and a concentration-dependent decrease in LPS-induced TNFα and IL-1ß production, while IL-10 production did not increase significantly (p>0.05). The anti-inflammatory and utero-relaxant effects induced by α-bisabolol were not associated with an increase in cAMP levels in pregnant human myometrial samples. These properties place α-bisabolol as a potentially safe and effective adjuvant agent in cases of preterm birth, an area of pharmacological treatment that requires urgent improvement.

Synergistic Interaction of Matricaria Chamomilla Extract with Diclofenac and Indomethacin on Carrageenan-Induced Paw Inflammation in Rats.

Preclinical Research The coadministration of non-steroidal anti-inflammatory drugs (NSAIDs) with medicinal plant extracts may increase anti-inflammatory activity, thus permitting the use of lower NSAID doses and limiting the side effects. The aim of this study was to explore the interactions between an ethanolic extract of M. chamomilla extract (MCE) with two NSAIDs, diclofenac and indomethacin on carrageenan-induced paw inflammation and gastric injury in rats. Diclofenac, indomethacin and MCE, or combinations with MCE produced an anti-inflammatory effect. Effective dose (ED) values were estimated for the individual drugs, and isobolograms were constructed. The final experimental ED values were 483.7 mg/kg for diclofenac + MCE combination, and 212.6 mg/kg for indomethacin + MCE. These values were lower (p < 0.05) than the theoretical ED values (1186.9 mg/kg for diclofenac + MCE combination, and 1183.8 mg/kg for indomethacin + MCE). These data suggest that the interactions between NSAIDs and MCE that mediate the anti-inflammatory effects at the systemic level are synergistic and may have therapeutic advantages for the clinical treatment of inflammatory processes. Drug Dev Res 78 : 360-367, 2017. © 2017 Wiley Periodicals, Inc.

Relaxant and anti-inflammatory effect of two thalidomide analogs as PDE-4 inhibitors in pregnant rat uterus.

The aim of this study was to evaluate the relaxant and anti-inflammatory effects of two thalidomide analogs as phosphodiesterase-4 (PDE-4) inhibitors in pregnant rat uterus. Uteri from Wistar female rats were isolated at 19 day of pregnancy. Uterine samples were used in functional studies to evaluate the inhibitory effects of the thalidomide analogs, methyl 3-(4-nitrophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4NO2PDPMe) and methyl 3-(4-aminophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4APDPMe), on prostaglandin-F2α (PGF2α)-induced phasic, K+-induced tonic, and Ca2+-induced contractions. Accumulation of cAMP was quantified in uterine homogenates by ELISA. Anti-inflammatory effect was assessed by using ELISA for determination of the pro-inflammatory cytokines tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß, and anti-inflammatory IL-10, from uterine explants stimulated with lipopolysaccharide (LPS). Nifedipine, forskolin and rolipram were used as positive controls where required. Both thalidomide analogs induced a significant inhibition of the uterine contractions induced by the pharmaco- and electro-mechanic stimuli. Nifedipine and forskolin were more potent than the analogs to inhibit the uterine contractility, but these were more potent than rolipram, and 4APDPMe was equieffective to nifedipine. Thalidomide analogs increased uterine cAMP-levels in a concentration-dependent manner. The LPS-induced TNFα and IL-1ß uterine secretion was diminished in a concentration-dependent fashion by both analogs, whereas IL-10 secretion was increased significantly. The thalidomide analogs induced utero-relaxant and anti-inflammatory effects, which were associated with the increased cAMP levels as PDE-4 inhibitors in the pregnant rat uterus. Such properties place these thalidomide analogs as potentially safe and effective tocolytic agents in a field that urgently needs improved pharmacological treatments, as in cases of preterm labor.

Inhibition of Uterine Contractility by Thalidomide Analogs via Phosphodiesterase-4 Inhibition and Calcium Entry Blockade.

Uterine relaxation is crucial during preterm labor. Phosphodiesterase-4 (PDE-4) inhibitors have been proposed as tocolytics. Some thalidomide analogs are PDE-4 inhibitors. The aim of this study was to assess the uterus-relaxant properties of two thalidomide analogs, methyl 3-(4-nitrophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4NO2PDPMe) and methyl 3-(4-aminophthalimido)-3-(3,4-dimethoxyphenyl)-propanoate (4APDPMe) and were compared to rolipram in functional studies of spontaneous phasic, K⁺-induced tonic, and Ca2+-induced contractions in isolated pregnant human myometrial tissues. The accumulation of cAMP was quantified in HeLa cells. The presence of PDE-4B2 and phosphorylated myosin light-chain (pMLC), in addition to the effect of thalidomide analogs on oxytocin-induced pMLC, were assessed in human uterine myometrial cells (UtSMCs). Thalidomide analogs had concentration-dependent inhibitory effects on spontaneous and tonic contractions and inhibited Ca2+-induced responses. Tonic contraction was equipotently inhibited by 4APDPMe and rolipram (IC50 = 125 ± 13.72 and 98.45 ± 8.86 µM, respectively). Rolipram and the thalidomide analogs inhibited spontaneous and tonic contractions equieffectively. Both analogs increased cAMP accumulation in a concentration-dependent manner (p < 0.05) and induced changes in the subcellular localization of oxytocin-induced pMLC in UtSMCs. The inhibitory effects of thalidomide analogs on the contractions of pregnant human myometrium tissue may be due to their PDE-4 inhibitory effect and novel mechanism as calcium-channel blockers.

Structure-activity relationships of aromadendranes in uterus-relaxant activity.

Aromadendranes belong to a class of sesquiterpenes present in higher plant essential oils and marine animals. Although the biological activities include antifungal, antibacterial, antiviral, plant growth regulatory, antifeedant, repellent and cytotoxic, there is only one precedent for spasmolytic effects. In a previous report we have shown that the aromadendrene molecule known as spathulenol, isolated from Lepechinia caulescens, efficiently relaxes rat uterus rings and therefore in the present work we describe structure-activity relationships of thirteen aromadendranes, most of them having the trans-fused perhydroazulene skeleton, with spasmolytic activity.

Spasmolytic effect of constituents from Lepechinia caulescens on rat uterus.

Lepechinia caulescens Ortega Epling (Lamiaceae) is a perennial herb used in Mexican folk medicine to treat diabetes, hypertension, gastrointestinal infections, dysmenorrhea and as abortifacient. In this study, a bioassay-guided fractionation of the hexanes extract of the leaves, evaluating the capacity to relax contraction of rat uterus rings induced by KCl (60mM), was made. The results indicated that, from the four isolated terpenes, spathulenol (1) was the most potent spasmolytic agent, followed by methyl 9alpha,13alpha-epidioxyabiet-8(14)-en-18-oate (2), 9alpha-hydroxydehydroabietyl alcohol (4) and dehydroabietic acid (3) studied at 10 and 30 microg/mL. The spasmolytic activity of 1 was totally reverted by addition of increasing extracellular Ca2+ concentrations ([Ca2+]o), while incubation of uterus rings with 1 in calcium free solutions reduced the contraction produced by [Ca2+]o in a concentration-dependent manner. Moreover, the presence of L-NAME (100 microM) or propranolol (10 microM) did not block the spasmolytic effect. These results suggest that 1 induces a greater blocking action on voltage-operated calcium channels. EtOAc and MeOH extracts of the leaves, which showed slight relaxing activity, led to 4 and rosmarinic acid (5).

Chemical composition and antispasmodic effect of Casimiroa pringlei essential oil on rat uterus.

The Casimiroa pringlei essential oil was analyzed to determine its chemical composition. Its effect on rat uterine smooth muscle was studied and compared with verapamil. Pure commercial piperitone, eucalyptol, and alpha-terpineol, the major constituents of C. pringlei essential oil, were tested on the uterine tonic contraction induced by high-potassium depolarizing solution (KCl 60 mM).

Evaluation of the interaction between acemetacin and opioids on the hargreaves model of thermal hyperalgesia.

It has been shown that the association of opioids analgesic agents with non-steroidal anti-inflammatory drugs (NSAIDs) can increase their antinociceptive activity, allowing the use of lower doses and thus limiting side effects. Therefore, the goal of the present study was to examine the possible pharmacological interaction between acemetacin and two opioids in the Hargreaves model of thermal hyperalgesia in the mouse. Acemetacin, codeine, nalbuphine or fixed-dose ratios acemetacin-codeine and acemetacin-nalbuphine combinations were administrated systemically to mice and the antihyperalgesic effect was evaluated using the thermal hyperalgesia test. All treatments produced a dose-dependent antihyperalgesic effect. ED40 values were estimated for all the treatments and an isobologram was constructed. The derived theoretical ED40 for the acemetacin-codeine and acemetacin-nalbuphine combinations were 55.9+/-4.9 mg/kg and 40.3+/-3.8 mg/kg, respectively, being significantly higher than the actually observed experimental ED40, 14.5+/-1.7 mg/kg and 12.7+/-2.2 mg/kg, respectively. These results correspond to synergistic interactions between acemetacin and opioids on the Hargreaves model of thermal hyperalgesia. Highest doses of the individual drugs or the combinations did not affect motor coordination in the balancing test on a rota-rod. Data suggest that low doses of the acemetacin-opioids combination can interact synergistically at systemic level and therefore this drugs association may represent a therapeutic advantage for the clinical treatment of inflammatory pain.

Drug treatment of hypertension: compliance and adverse reactions in a cohort of hypertensive patients in a primary care setting.

OBJECTIVES: The primary was to assess the frequency of therapeutic non-compliance due to ADRs in a cohort of patients with recently diagnosed systemic hypertension. The secondary objectives were to evaluate the blood pressure control during the follow-up in the whole cohort and in patients who received non-steroidal anti-inflammatory drugs (NSAIDs). METHODS: A cohort of 73 recently diagnosed ambulatory hypertensive patients was followed-up for 6 months. Validated questionnaires for identification of therapeutic scheme changes and ADRs were applied monthly, during each medical visit. RESULTS: Family physicians selected monotherapy in 79% of patients. The frequency of therapeutic non-compliance was 44%; non-compliance secondary to ADR was 7%. Systolic and diastolic blood pressure at the beginning of the study were 140 +/- 15/90 +/- 15 mm Hg for the whole cohort. At the end of the study the figures were 130 +/- 11/85 +/- 6 (p < 0.001). Patients receiving non-steroidal anti-inflammatory drugs (NSAIDs) had higher blood pressure levels than the groups of patients not receiving such kind of drugs (134 +/- 10 vs. 128 +/- 8 mm Hg, p = 0.025 and 88 +/- 7 vs. 83 +/- 5 mm Hg, p = 0.05). CONCLUSIONS: The drugs used in the present study as monotherapy are considered acceptable choices for hypertension treatment. The frequency of therapeutic non-compliance was within the limits reported in the literature and the frequency of therapeutic non-compliance secondary to ADRs in this cohort was lower than that reported in the literature. Higher blood pressure was found in the group of patients receiving NSAIDs.

Nurses' and Nursing Students' Knowledge and Attitudes regarding Pediatric Pain.

Nursing staff spend more time with patients with pain than any other health staff member. For this reason, the nurse must possess the basic knowledge to identify the presence of pain in patients, to measure its intensity and make the steps necessary for treatment. Therefore, a prospective, descriptive, analytical, and cross-sectional study was conducted to investigate the knowledge and attitudes regarding pediatric pain in two different populations. The questionnaire, Pediatric Nurses Knowledge and Attitudes Survey Regarding Pain (PKNAS), was applied to 111 hospital pediatric nurses and 300 university nursing students. The final scores for pediatric nurses and nursing students were 40.1 ± 7.9 and 40.3 ± 7.5, respectively. None of the sociodemographic variables predicted the scores obtained by the participants (P > 0.05). There was a high correlation between the PKNAS scores of pediatric nurses and nursing students (r = 0.86, P < 0.001). It was observed that the degree of knowledge about pain and its treatment was very low in both groups. Due to this deficiency, pain in children remains inadequately managed, which leads to suffering in this population. It is necessary to increase the continued training in this subject in both areas.

Anatomical differences in uterine sensitivity to prostaglandin F(2alpha) and serotonin in non-pregnant rats.

The ovarian steroids regulate the sensitivity of a population of uterine receptors to prostaglandin F(2alpha), serotonin and oxytocin. However, the uterine sensitivity to prostaglandin F(2alpha) and oxytocin does not coincide with the estrogen-induced increase in the number of receptors. Anatomical differences affect the uterine sensitivity to agonists. We investigated whether anatomical differences between ovarian and cervical uterine regions modulate the hormone-regulated sensitivity to prostaglandin F(2alpha), serotonin and oxytocin. Non-cumulative concentration-response curves for these agonists were recorded for ovarian and cervical uterine segments from adult ovariectomized rats treated with 17beta-estradiol, 17beta-estradiol+progesterone, or vehicle. The ovarian segments displayed a higher maximal response (E(max)) to prostaglandin F(2alpha) and a lower E(max) to serotonin than the cervical segments. Both uterine segments displayed a similar sensitivity to oxytocin. The ovariectomized controls displayed the highest E(max) and the lowest effective concentration 50 (EC(50)) for oxytocin and prostaglandin F(2alpha). Anatomical differences between ovarian and cervical uterine regions modulate the hormonal regulation of uterine sensitivity to serotonin and prostaglandin F(2alpha) in the non-pregnant rat uterus.

Role of ATP-sensitive K+ channels in the antinociception induced by non-steroidal anti-inflammatory drugs in streptozotocin-diabetic and non-diabetic rats.

There is evidence that systemic sulfonylureas block diclofenac-induced antinociception in normal rat, suggesting that diclofenac activates ATP-sensitive K(+) channels. However, there is no evidence for the systemic interaction between different non-steroidal anti-inflammatory drugs (NSAIDs) and sulfonylureas in streptozotocin (STZ)-diabetic rats. Therefore, this work was undertaken to determine whether two sulfonylureas, glibenclamide and glipizide, have any effect on the systemic antinociception that is induced by diclofenac (30 mg/kg), lumiracoxib (56 mg/kg), meloxicam (30 mg/kg), metamizol (56 mg/kg) and indomethacin (30 mg/kg) using the non-diabetic and STZ-diabetic rat formalin test. Systemic injections of NSAIDs produced dose-dependent antinociception during the second phase of the test in both non-diabetic and STZ-diabetic rats. Systemic pretreatment with glibenclamide (10 mg/kg) and glipizide (10 mg/kg) blocked diclofenac-induced systemic antinociception in the second phase of the test (P<0.05) in both non-diabetic and STZ-diabetic rats. In contrast, pretreatment with glibenclamide or glipizide did not block lumiracoxib-, meloxicam-, metamizol-, and indomethacin-induced systemic antinociception (P>0.05) in both groups. Results showed that systemic NSAIDs are able to produce antinociception in STZ-diabetic rats. Likewise, data suggest that diclofenac, but not other NSAIDs, activated K(+) channels to induce its systemic antinociceptive effect in the non-diabetic and STZ-diabetic rat formalin test.

Effect of diclofenac with B vitamins on the treatment of acute pain originated by lower-limb fracture and surgery.

The aim of this study was to compare the efficacy of diclofenac, for the treatment of acute pain originated by lower-limb fracture and surgery, with that of diclofenac plus B vitamins. This was a single-center, prospective, randomized, and double-blinded clinical trial. Patients with lower-limb closed fractures rated their pain on a 10 cm visual analog scale (VAS). Patients were then randomized to receive diclofenac or diclofenac plus B vitamins (thiamine, pyridoxine, and cyanocobalamin) intramuscularly twice daily. Patient evaluations of pain intensity were recorded throughout two periods: twenty-four hours presurgery and twenty-four hours postsurgical. One hundred twenty-two patients completed the study. The subjects' assessments of limb pain on the VAS showed a significant reduction from baseline values regardless of the treatment group. Diclofenac plus B vitamins combination was more effective to reduce the pain than diclofenac alone. The results showed that the addition of B vitamins to diclofenac increased its analgesic effect. The novelty of this paper consists in that diclofenac and diclofenac plus B vitamins were useful for treatment of acute pain originated by lower-limb fracture and surgery.

Synergistic relaxing effect of the paracetamol and pyrilamine combination in isolated human myometrium.

OBJECTIVE: To evaluate the interaction type of the human uterine relaxant effect of the paracetamol-pyrilamine combination (PPC) in vitro. STUDY DESIGN: Uterine strips were contracted with KCl (60 mM) and treated with vehicle or increasing concentrations of paracetamol (100-3200 µM), pyrilamine (3.2-100 µM) or the PPC. The relaxing effects of the drugs alone and in combination were measured. Isobolographic analysis was used to determine the pharmacologic interaction type. RESULTS: Paracetamol, pyrilamine and the PPC produced a significant relaxing effect on non-pregnant human uterine strips pre-contracted with KCl (60 mM). The EC30 values for paracetamol and pyrilamine on the uterine contraction were 2391.3±595.3 µM and 14.7±1.7 µM, respectively. The derived experimental EC30 for the PPC was 401.8±129.8 µM. This value was significantly lower (p<0.05) than the theoretical EC30 expected for a purely additive interaction, which was 1203.0±297.7 µM for the PPC. The interaction index (γ) was 0.33±0.14 for PPC, being statistically different from unity. CONCLUSION: Data suggest that low doses of the PPC can interact synergistically and therefore this drug association may represent a therapeutic advantage for the clinical treatment of dysmenorreic pain.

Synergistic effect of the interaction between naproxen and citral on inflammation in rats.

The combination of non-steroidal anti-inflammatory drugs with herbs having analgesic effects can increase their antinociceptive activity and limit their side effects. The aim of the present study was to examine the effects on inflammation and gastric injury in rats resulting from the interaction between naproxen and citral. Naproxen, citral, or fixed-dose naproxen-citral combinations were administered orally and their anti-inflammation (carrageenan-induced paw edema) and gastric damage were assessed in rats. The pharmacological interaction type was evaluated by the isobolographic analysis. Naproxen, citral, or combinations of naproxen and citral produced anti-inflammatory effects. The sole administration of naproxen produced significant gastric damage, but this effect was not obtained with either citral or combinations. ED(30) values were estimated for the individual drugs, and isobolograms were constructed. The derived theoretical ED(30) for the anti-inflammatory effect was 504.4 mg/kg; this was significantly higher than the observed experimental value (190.6 mg/kg). These results indicate that a synergistic interaction underlies the anti-inflammatory effect. The data suggests that the naproxen-citral combination can interact and to produce minor gastric damage and may have therapeutic advantages for the clinical treatment of inflammation.

Spasmolytic and anti-inflammatory effects of Aloysia triphylla and citral, in vitro and in vivo studies.

Aloysia triphylla is traditionally utilized for the treatment of menstrual colic (primary dysmenorrhea) in Mexico. Citral is the main chemical component found in Aloysia triphylla leaves extract. Primary dysmenorrhea is a very frequent gynecological disorder in menstruating women, affecting 30-60% of them. It is usually treated with non-steroidal anti-inflammatory drugs (NSAIDs); although their effect is rapid, they possess many side effects. Due to these shortcomings, Mexican folk therapy is considered as a feasible alternative. The effects of the hexane extract of Aloysia triphylla and citral on uterine contractions were evaluated in vitro as well as their anti-inflammatory properties and gastric wound capabilities were assessed in vivo. The inhibitory effects on the contractions were analyzed using isolated uterus strips from estrogen primed rats. Contractions were induced by KCl 60 mM, oxytocin 10 mIU/mL, charbacol 10 µM and PGF(2α) 5 µM. The anti-inflammatory effect was assessed on carrageenan-induced rat hind paw edema model. The inhibitory concentration-50 (IC(50)) of the hexane extract of Aloysia triphylla upon each contractile response was for KCl 44.73 ± 2.48 µg/mL, oxytocin 42.16 ± 3.81 µg/mL, charbacol 41.87 ± 1.73 µg/mL and PGF(2α) 28.70 ± 2.40 µg/mL in a concentration-dependent way. The extract of Aloysia triphylla produced a significant inhibitory effect on PGF(2α)-induced contraction compared to its inhibitory actions on the others. Citral exhibited the same inhibitory effect on the contraction induced by PGF(2α). The oral administration of the extract (100-800 mg/kg) and citral (100-800 mg/kg) showed anti-inflammatory activity; furthermore, the maximal dose utilized did not produce gastric injury. These results were compared with anti-inflammatory effects and gastric damage produced by 30 mg/kg of indomethacin p.o. The spasmolytic and anti-inflammatory effects support the traditional use of Aloysia triphylla leaves in the treatment of the primary dysmenorrhea in Mexican communities.

The combination of naproxen and citral reduces nociception and gastric damage in rats.

It has been shown that the association of non-steroidal anti-inflammatory drugs with plant extracts can increase their antinociceptive activity, allowing the use of lower doses and, thus, limiting side effects. Therefore, the aim of this study was to examine the effects of the interaction between naproxen and citral on nociception and gastric injury in rats. Naproxen, citral, or combinations of naproxen and citral produced an antinociceptive effect. The administration of naproxen produced significant gastric damage, but this effect was not obtained with either citral or the naproxen-citral combination. The ED(50) value was estimated for the individual drugs and an isobologram was constructed. The derived theoretical ED(50) for the antinociceptive effect (423.8 mg/kg) was not significantly different from the observed experimental value (359.0 mg/kg); hence, the interaction between naproxen and citral mediating the antinociceptive effect is additive. These data suggest that the naproxen-citral combination interacts at the systemic level, produces minor gastric damage, and potentially has therapeutic advantages for the clinical treatment of inflammatory pain.

Pharmacological interaction between gabapentin and glibenclamide in the formalin test in the diabetic rat.

There is evidence that local peripheral administration of gabapentin produces antinociception through the activation of the ATP-sensitive K+-channel. However, this interaction has not been evaluated systemically, nor in diabetic rat. This work was undertaken to determine whether glibenclamide has any effect on the systemic antinociception induced by gabapentin. Inflammatory pain was induced by injection of formalin in diabetic rats. Reduction of flinching behavior was considered as antinociception. Systemic administration of gabapentin (10-56 mg/kg, i.p.) produced a dose-dependent antinociception in both phases of the formalin test. Also, glibenclamide (1-10 mg/kg, s.c.) blocked the gabapentin-induced antinociception. Given alone glibenclamide did not significantly modify formalin-induced nociception in diabetic rats. Our data suggest that gabapentin is able to reduce formalin-induced nociception in streptozotocin-injected rats. In addition, these data are consistent with gabapentin-mediated activation of ATP-sensitive-K+ channels to produce systemic antinociception in the formalin test in diabetic rats.