Bioactivation of nitroglycerin to nitric oxide (NO) and S-nitrosothiols in the rat liver and evaluation of the coexisting hypotensive effect

Ensuring safety and efficacy in combination products: regulatory challenges and best practices

Combination products, amalgamating drugs, biologics, and medical devices, have revolutionized the healthcare landscape with their potential for innovative therapies. However, the intersection of diverse components within these products presents a complex regulatory environment, demanding rigorous attention to safety and efficacy. This article delves into the intricate landscape of regulatory considerations, safety, and efficacy assessments pertaining to combination products-a category at the intersection of drugs, devices, and biologics. The regulatory framework, primarily governed by the U.S. Food and Drug Administration (FDA), necessitates a nuanced classification determining the regulatory pathway. Collaboration between diverse regulatory centers, such as the Center for Drug Evaluation and Research (CDER) and the Center for Devices and Radiological Health (CDRH), underscores the integrated approach required for these innovative healthcare solutions. Safety considerations unravel the potential risks and adverse events associated with combining diverse components, emphasizing the need for robust risk assessment and mitigation strategies. The evaluation of efficacy involves sophisticated methodologies, clinical trials, and post-market surveillance, with recent advancements incorporating digital technologies. This comprehensive exploration aims to contribute to the evolving understanding and best practices in the regulatory and scientific realms, fostering collaboration and innovation in the development and assessment of combination products.

Disulfiram and metformin combination anticancer effect reversible partly by antioxidant nitroglycerin and completely by NF-κB activator mebendazole in hamster fibrosarcoma

We investigated the anticancer effect of disulfiram and metformin combination on fibrosarcoma in hamsters. Hamsters of both sexes (~ 70 g) were randomly allocated to control and experimental groups (8 animals per group). In all 10 groups, 2 × 10⁶ BHK-21/C13 cells in 1 ml were injected subcutaneously into the animals' backs. Peroral treatments were carried out with disulfiram 50 mg/kg daily, or with metformin 500 mg/kg daily, or with their combination. Validation and rescue grups were treated by double doses of the single therapy and by the combination with addition of rescue daily doses of ROS inhibitor nitroglycerin 25 mg/kg or NF-κB stimulator mebendazole 460 mg/kg, via a gastric probe after tumor inoculation. After 19 days all animals were sacrificed. Blood samples were collected for hematological and biochemical analyses, the tumors were excised and weighed, and their diameters and volumes were measured. The tumor samples were pathohistologically and immunohistochemically assessed (Ki-67, PCNA, CD34, CD31, COX4, Cytochrome C, GLUT1, iNOS), and the main organs were toxicologically tested. The combination of disulfiram and metformin significantly inhibited fibrosarcoma growth in hamsters without toxicity, compared to monotherapy or control. The single treatments did not show significant antisarcoma effect. Co-treatment with nitroglycerin partly rescued tumor progression, probably by ROS inhibition, while mebendazole completely blocked anticancer activity of the disulfiram and metformin combination, most likely by NF-κB stimulation. Combination of disulfiram with metformin may be used as an effective and safe candidate for novel nontoxic adjuvant and relapse prevention anticancer therapy.

Enhancing vascular relaxing effects of nitric oxide-donor ruthenium complexes

Ruthenium-derived complexes have emerged as new nitric oxide (NO) donors that may help circumvent the NO deficiency that impairs vasodilation. NO in vessels can be produced by the endothelial cells and/or released by NO donors. NO interacts with soluble guanylyl-cyclase to produce cGMP to activate the kinase-G pathway. As a result, conductance arteries, veins and resistance arteries dilate, whereas the cytosolic Ca2+ levels in the smooth muscle cells decrease. NO also reacts with oxygen or the superoxide anion, to generate reactive oxygen species that modulate NO-induced vasodilation. In this article, we focus on NO production by NO synthase and discuss the vascular changes taking place during hypertension originating from endothelial dysfunction. We will describe how the NO released from ruthenium-derived complexes enhances the vascular effects arising from failed NO generation or lack of NO bioavailability. In addition, how ruthenium-derived NO donors induce the hypotensive effect by vasodilation is also discussed.

Effect of genetic deletion and pharmacological antagonism of P2X7 receptors in a mouse animal model of migraine

BACKGROUND

Purine receptors participate in peripheral and central sensitization and are associated with migraine headache. We investigated the role of P2X7 receptor (P2X7) in a nitroglycerin (NTG)-induced mouse model of migraine.

METHODS

Intraperitoneal NTG injection (15 mg/kg) triggered thermal hyperalgesia in the hindpaws of wild-type C57BL/6J mice, followed by the induction of c-fos in upper cervical spinal cord and trigeminal nucleus caudalis. The effect of genetic deletion of P2X7 and the selective P2X7 antagonist Brilliant Blue G (BBG) were examined on hyperalgesia and c-fos induction.

RESULTS

NTG decreased the paw withdrawal threshold in both wild-type and P2X7 knockout mice. Nevertheless, subacute BBG treatment (50 mg/kg/day i.p.) completely prevented the effect of NTG in wild-type, but not in knockout mice. Whereas P2X7 deficiency differentially affected the expression of c-fos, the average number of fos-immuno-reactive neurons in trigeminal nucleus caudalis, but not in upper cervical spinal cord was lower in BBG-treated wild-type mice after NTG treatment.

CONCLUSIONS

Our results show that P2X7 receptors might participate in the pathogenesis of migraine, although upregulation of other P2X receptors probably compensate for the loss of its action in knockout mice. The data also suggest the therapeutic potential of P2X7 antagonists for the treatment of migraine.

Sumatriptan alleviates nitroglycerin-induced mechanical and thermal allodynia in mice

The association between the clinical use of nitroglycerin (NTG) and headache has led to the examination of NTG as a model trigger for migraine and related headache disorders, both in humans and laboratory animals. In this study in mice, we hypothesized that NTG could trigger behavioural and physiological responses that resemble a common manifestation of migraine in humans. We report that animals exhibit a dose-dependent and prolonged NTG-induced thermal and mechanical allodynia, starting 30-60 min after intraperitoneal injection of NTG at 5-10 mg/kg. NTG administration also induced Fos expression, an anatomical marker of neuronal activity in neurons of the trigeminal nucleus caudalis and cervical spinal cord dorsal horn, suggesting that enhanced nociceptive processing within the spinal cord contributes to the increased nociceptive behaviour. Moreover, sumatriptan, a drug with relative specificity for migraine, alleviated the NTG-induced allodynia. We also tested whether NTG reduces the threshold for cortical spreading depression (CSD), an event considered to be the physiological substrate of the migraine aura. We found that the threshold of CSD was unaffected by NTG, suggesting that NTG stimulates migraine mechanisms that are independent of the regulation of cortical excitability.

The protective effect of nitroglycerin on gastrointestinal and renal side effects of lornoxicam in rats

The aim of this study is firstly, to determine the preventive effect of chronic usage of combination of nitroglycerin and lornoxicam on gastrointestinal and renal side effects and secondly, to investigate the oxidative and antioxidative effects of this combination in rats.

METHODS

Thirty-seven Wistar male rats were divided into five groups for 15 days; isotonic group (n = 8, sodium chloride 0.09, Group ISO), lornoxicam group (n = 8, lornoxicam 1.3 mg/kg, Group L), nitroglycerin group (n = 6, nitroglycerin 1 mg/kg, Group NTG), lornoxicam-nitroglycerin combination group (n = 8, 1.3 mg/kg lornoxicam + 1 mg/kg nitroglycerin, Group L-NTG), and control group (n = 7, no drug was administered, Group C). Nitric oxide, malondialdehyde, reduced glutathione (GSH), catalase, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha concentrations were measured before drug injection and on fifteenth day in all blood samples. Gastrointestinal and renal biopsies were performed on fifteenth day.

RESULTS

Two rats died on tenth and twelfth days in Group L. There were significant differences in Group L compared to the other groups for the lesions of stomach and kidney (p = 0.01, p = 0.028 respectively). Gastric ulceration was occurred in a rat in Group L. Malondialdehyde, TNF-alpha, and IL-6 levels decreased in NTG and L-NTG groups, whereas catalase and glutathion levels increased in NTG, L and L-NTG groups compared to control group (p < 0.05).

CONCLUSION

Lornoxicam may cause gastrointestinal and renal side effects without oxidative stress. Adding nitroglycerin to lornoxicam for chronic treatment may prevent these side effects and enhance antioxidative effect compared to the use of lornoxicam alone in rats.

Effects of nitroglycerin on erythrocyte rheology and oxygen unloading: novel role of S-nitrosohemoglobin in relieving myocardial ischemia

BACKGROUND

We hypothesized that nitroglycerin improves O2 delivery to ischemic tissue by altering erythrocyte rheology and O2 unloading through an increase in bioactive nitric oxide (NO) content.

METHODS AND RESULTS

Twelve dogs with resting flow-reducing single-vessel stenosis were studied at rest and during intracoronary infusion of nitroglycerin (0.3 to 0.6 microg.kg(-1).min(-1)). Half the dogs also had occlusion of the remote coronary artery to remove any collateral effects. Systemic and coronary hemodynamics, myocardial blood flow (MBF), whole blood viscosity (WBeta), erythrocyte charge (EC) and mobility (EM), regional myocardial O2 delivery and consumption, and tissue O2 pressure (Po2) were measured. No changes in systemic hemodynamics were seen with nitroglycerin. Despite flow-limiting stenosis, MBF increased significantly in the central 25% of the ischemic bed, which was associated with an approximately 19% decrease in WBeta. There was a good correlation (r=0.87) between the two. The decrease in WBeta was associated with a decrease in EC and an increase in EM (r=0.83). The nitroglycerin-induced increase in tissue Po2 was disproportionate to the increase in MBF, indicating enhanced O2 unloading. Erythrocyte S-nitrosothiol content (reflecting mainly S-nitrosohemoglobin) was significantly higher for blood exposed in vitro to 0.1 micromol/L nitroglycerin or the NO donor SNAP, as compared with control (18.9+/-8.8 and 10.5+/-6.5 versus 2.6+/-0.5x10(-5), P<0.05).

CONCLUSIONS

The augmented MBF in the ischemic microcirculation during nitroglycerin administration occurs in tandem with increased erythrocyte S-nitrosothiol content, EM, and O2 unloading. These additional microvascular mechanisms may contribute to the powerful antiischemic effects of nitroglycerin, especially during low-flow states.