Duloxetine hydrochloride loaded film forming dermal gel enriched with methylcobalamin and geranium oil attenuates paclitaxel-induced peripheral neuropathy in rats

Abstract

Objective: In attempt to conquer the major concerns of oral duloxetine hydrochloride (like low bioavailability, intolerable side-effects and no regeneration of demyelinated nerve fibres) for the management of chemotherapy-induced peripheral neuropathy (CIPN), an alternative delivery of duloxetine hydrochloride was aimed for in-vivo optimization.

Methods: A film forming dermal gel consisting of duloxetine hydrochloride was formulated and enriched with methylcobalamin and geranium oil. The formulated gel successfully qualified the various pharmaceutical characteristics of gel. Administration of paclitaxel (8 mg/kg/i.p. in four divided doses) for 4 alternate days induced the symptoms of peripheral neuropathy in rats. On 14th day, the responses to noxious stimulus (mechanical hyperalgesia, cold allodynia, and heat hyperalgesia) were increased and reached to its maximum. Thereafter, drug treatment with formulated dermal gel and oral duloxetine hydrochloride (30 mg/kg, once daily) was initiated for 2 weeks in different group of animals. On the 28th day animals were sacrificed to isolate sciatic nerve, to assess biochemical changes (TBARS, reduced GSH, total protein, TNF-α, IL-6) and for histopathological examinations of nerve sections using Hematoxylin-Eosin and Toludine blue staining methods.

Results: Application of formulated dermal gel to paclitaxel-treated rats significantly improved paw-withdrawal latency responses during noxious stimulus testing, reduced the levels of TBARS, TNF-α, IL-6 and elevated the levels of reduced GSH as compared to paclitaxel treated rats. Histographs also indicated marked regeneration of the damaged nerve fibers. Topical delivery of duloxetine hydrochloride produced similar results in disparity to oral route. However, no significant disparity in responses was obtained with twice application of formulated dermal gel when compared to once daily application.

Conclusion: Tremendous recovery from nociception, oxidation and inflammation in addition to nerve degeneration was achieved through dermal application of duloxetine hydrochloride in peripheral neuropathy.

Keywords: Chemotherapy-induced peripheral neuropathy; Duloxetine hydrochloride; Film forming dermal gel; Methylcobalamin; Paclitaxel.

Fig. 1

Graphical illustration of rat behavior modulation for mechanical hyperalgesia (paw withdrawal threshold in grams). Paw withdrawal latency test data for normal control, paclitaxel control, Paclitaxel + Oral Duloxetine HCl, Paclitaxel + Formulated dermal gel (once a day), Paclitaxel + Formulated dermal gel (twice a day) groups on different days of the investigation. Normal control: untreated group, Paclitaxel control: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days, Paclitaxel + Oral Duloxetine HCl: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by duloxetine HCl (30 mg/kg, once a day for 14 days), Paclitaxel + Formulated dermal gel (once a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application once a day on hind paws of rats for 14 days, Paclitaxel + Formulated dermal gel (twice a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application twice a day on hind paws of rats for 14 days. The values are expressed as mean ± standard deviation (SD), n = 6. a depicts statistically significant differences (p < 0.05) between paclitaxel control and normal control. b depicts statistically significant differences (p < 0.05) between paclitaxel control vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (once a day)/Paclitaxel + Formulated dermal gel (twice a day). c depicts statistically insignificant differences (p > 0.05) between Paclitaxel + Formulated dermal gel (once a day) vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (twice a day).

Fig. 2

Graphical illustration of rat behavior modulation for cold allodynia (paw-lifting duration in seconds). Paw lifting latency test data for for normal control, paclitaxel control, Paclitaxel + Oral Duloxetine HCl, Paclitaxel + Formulated dermal gel (once a day), Paclitaxel + Formulated dermal gel (twice a day) groups on different days of the investigation. Normal control: untreated group, Paclitaxel control: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days, Paclitaxel + Oral Duloxetine HCl: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by duloxetine HCl (30 mg/kg, once a day for 14 days), Paclitaxel + Formulated dermal gel (once a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application once a day on hind paws of rats for 14 days, Paclitaxel + Formulated dermal gel (twice a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application twice a day on hind paws of rats for 14 days. The values are expressed as mean ± standard deviation (SD), n = 6. a depicts statistically significant differences (p < 0.05) between paclitaxel control and normal control. b depicts statistically significant differences (p < 0.05) between paclitaxel control vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (once a day)/Paclitaxel + Formulated dermal gel (twice a day). c depicts statistically insignificant differences (p > 0.05) between Paclitaxel + Formulated dermal gel (once a day) vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (twice a day).

Fig. 3

Graphical illustration of rat behavior modulation for heat hyperalgesia (paw withdrawal threshold in seconds). Paw withdrawal latency test data for for normal control, paclitaxel control, Paclitaxel + Oral Duloxetine HCl, Paclitaxel + Formulated dermal gel (once a day), Paclitaxel + Formulated dermal gel (twice a day) groups on different days of the investigation. Normal control: untreated group, Paclitaxel control: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days, Paclitaxel + Oral Duloxetine HCl: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by duloxetine HCl (30 mg/kg, once a day for 14 days), Paclitaxel + Formulated dermal gel (once a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application once a day on hind paws of rats for 14 days, Paclitaxel + Formulated dermal gel (twice a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application twice a day on hind paws of rats for 14 days. The values are expressed as mean ± standard deviation (SD), n = 6. a depicts statistically significant differences (p < 0.05) between paclitaxel control and normal control. b depicts statistically significant differences (p < 0.05) between paclitaxel control vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (once a day)/Paclitaxel + Formulated dermal gel (twice a day). c depicts statistically insignificant differences (p > 0.05) between Paclitaxel + Formulated dermal gel (once a day) vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (twice a day).

Fig. 4

Measurement of TBARS level (nM/mg of protein) and reduced GSH level (μM/mg of protein) in rat sciatic nerve in normal control, paclitaxel control, Paclitaxel + Oral Duloxetine HCl, Paclitaxel + Formulated dermal gel (once a day), Paclitaxel + Formulated dermal gel (twice a day) groups. Normal control: untreated group, Paclitaxel control: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days, Paclitaxel + Oral Duloxetine HCl: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by duloxetine HCl (30 mg/kg, once a day for 14 days), Paclitaxel + Formulated dermal gel (once a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application once a day on hind paws of rats for 14 days, Paclitaxel + Formulated dermal gel (twice a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application twice a day on hind paws of rats for 14 days. The values are expressed as mean ± standard deviation (SD), n = 6. a depicts statistically significant differences (p < 0.05) between paclitaxel control and normal control. b depicts statistically significant differences (p < 0.05) between paclitaxel control vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (once a day)/Paclitaxel + Formulated dermal gel (twice a day). c depicts statistically insignificant differences (p > 0.05) between Paclitaxel + Formulated dermal gel (once a day) vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (twice a day).

Fig. 5

Measurement of TNF-α level (pg/mL of protein) and IL-6 level (pg/mL of protein) in rat sciatic nerve in for normal control, paclitaxel control, Paclitaxel + Oral Duloxetine HCl, Paclitaxel + Formulated dermal gel (once a day), Paclitaxel + Formulated dermal gel (twice a day) groups. Normal control: untreated group, Paclitaxel control: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days, Paclitaxel + Oral Duloxetine HCl: Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by duloxetine HCl (30 mg/kg, once a day for 14 days), Paclitaxel + Formulated dermal gel (once a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application once a day on hind paws of rats for 14 days, Paclitaxel + Formulated dermal gel (twice a day): Paclitaxel (8 mg/kg; i.p. in four divided doses) for 4 alternate days followed by formulated dermal gel application twice a day on hind paws of rats for 14 days. The values are expressed as mean ± standard deviation (SD), n = 6. a depicts statistically significant differences (p < 0.05) between paclitaxel control and normal control. b depicts statistically significant differences (p < 0.05) between paclitaxel control vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (once a day)/Paclitaxel + Formulated dermal gel (twice a day). c depicts statistically insignificant differences (p > 0.05) between Paclitaxel + Formulated dermal gel (once a day) vs Paclitaxel + Oral Duloxetine HCl/Paclitaxel + Formulated dermal gel (twice a day).

Fig. 6

Hematoxylin & eosin and Toluidine blue stained histopathological photomicrographs of the sciatic nerve in for normal control, paclitaxel control, Paclitaxel + Oral Duloxetine HCl, Paclitaxel + Formulated dermal gel (once a day), Paclitaxel + Formulated dermal gel (twice a day) groups. A and F: Normal control. B and G: Paclitaxel control. C and H: Paclitaxel + Oral Duloxetine HCl. D and I: Paclitaxel + Formulated dermal gel (once a day). E and J: Paclitaxel + Formulated dermal gel (twice a day). Yellow arrow represents- Longitudinally arranged nerve fibres. Black arrow represents- Schwann cell nuclei. Red arrow represents- Necrotic area. Orange arrow represents- Tortuous fibre tract.