Protective role of intratympanic nigella sativa oil against gentamicin induced hearing loss

Therapeutic benefits of natural oils along with permeation enhancing activity

The skin is the largest organ of the integumentary system with a multifunctional purpose to protect the body from heat and microbes, regulate body temperature, and act as a sensory organ. A topical dosage form applied on the skin will have to cross the stratum corneum, which would then allow the dosage form to traverse the subsequent layers of the skin. The drug with poor solubility and short half-life would serve as an ideal candidate for its delivery via the transdermal route. This review reports the role of natural oils in enhancing the permeation of drugs through skin as they possess different features like natural origin, favorable penetration enhancement, and partitioning action in the skin. Chemical penetration enhancers have been used widely but are associated with toxicities. Thus, more research should be channelized in the area of extraction of oils from natural sources, along with their active constituents, which can serve as therapeutic alternatives to various disorders and diseases. Natural oils are obtained from leaves, fruits, flowers, seeds, bark, and roots, which have a therapeutic potential as well as penetration enhancing activity. The demerits of oral drug delivery include degradation of drugs in the gastrointestinal tract, addition of taste masking, and coating of tablets, which can be overcome by delivering the drug via the transdermal route. Natural oil contains lipids, flavonoids, and terpenes, which play a significant role in anti-inflammatory and penetration enhancing activity.

Protective effect of creatine on amikacin-induced ototoxicity

Introduction

Aminoglycosides are widely known for their ototoxic side effects. Nevertheless, they are potent antibiotics used in the treatment of life-threatening conditions because of the current concern for antibiotic resistance. We hypothesized that creatine supplements which are believed to improve mitochondrial antioxidant defense system and maintain optimal energy homeostasis may improve the ototoxic side effects.

Objective

This study aimed to investigate the protective effects of creatine monohydrate against ototoxicity induced by amikacin in rats in an experimental animal model, using distortion product otoacoustic emissions and auditory brainstem response.

Methods

Twenty healthy rats were assigned to four groups (5 rats in each): the control group, the creatine monohydrate group, the amikacin group and the amikacin + creatine monohydrate group. The creatine monohydrate group received creatine at a dose of 2 g/kg once daily via gastric gavage for 21 days. The amikacin group received amikacin at a dose of 600 mg/kg by intramuscular injections once daily for 21 days. The amikacin + creatine monohydrate group received intramuscular injections of amikacin (600 mg/kg) once daily for 21 days and creatine monohydrate (2 g/kg) once daily via gastric gavage for 21 days. The control group received nothing. The distortion product otoacoustic emissions and auditory brainstem response measurements were performed on all rats on days 0, 7, 21.

Results

Regarding auditory brainstem response values, a significant increase in the auditory threshold was observed in the amikacin group on day 21 (p <  0.001). The amikacin+creatine monohydrate group showed significantly lower levels of auditory brainstem response auditory thresholds on day 21 in comparison to the amikacin group (p <  0.001). Additionally, the control group and the amikacin+creatine monohydrate group did not differ significantly with respect to auditory brainstem response thresholds on treatment day 21 (p >  0.05). When we compare distortion product otoacoustic emissions values, there was no significant difference between the amikacin and amikacin+creatine monohydrate groups on day 7 (p >  0.05), However significantly greater distortion product otoacoustic emissions values were observed in the amikacin+creatine monohydrate group on day 21 compared to the amikacin group (p <  0.001).

Conclusion

Our findings demonstrate that creatine treatment protects against amikacin ototoxicity when given at a sufficient dose and for an adequate time period.

Does Calcium Dobesilate Have Therapeutic Effect on Gentamicin-induced Cochlear Nerve Ototoxicity? An Experimental Study

HYPOTHESIS

The ototoxic effects of aminoglycosides are well known. Gentamicin carries a substantial risk of hearing loss. Gentamicin is widely used to combat life-threatening infections, despite its ototoxic effects. Calcium dobesilate is a pharmacologically active agent used to treat many disorders due to its vasoprotective and antioxidant effects. We investigated the therapeutic role of calcium dobesilate against gentamicin-induced cochlear nerve ototoxicity in an animal model.

METHODS

Thirty-two Sprague Dawley rats were divided into four groups: Gentamicin, Gentamicin + Calcium Dobesilate, Calcium Dobesilate, and Control. Preoperative and postoperative hearing thresholds were determined using auditory brainstem response thresholds with click and 16-kHz tone-burst stimuli. Histological analysis of the tympanic bulla specimens was performed under light and transmission electron microscopy. The histological findings were subjected to semiquantitative grading, of which the results were compared between the groups.

RESULTS

Gentamicin + Calcium Dobesilate group had, on average, 27 dB better click-evoked hearing than Gentamicin group (p < 0.01), whereas the difference was not significant with 16-kHz tone-burst stimuli (p > 0.01). Histologically examining the Control and Calcium Dobesilate groups revealed normal ultrastructural appearances. The Gentamicin group showed the most severe histological alterations including myelin destruction, total axonal degeneration, and edema. The histological evidence of damage was significantly reduced in the Gentamicin + Calcium Dobesilate group compared with the Gentamicin group.

CONCLUSION

Adding oral calcium dobesilate to systemic gentamicin was demonstrated to exert beneficial effects on click-evoked hearing thresholds, as supported by the histological findings.

Assessment of In Vitro Antigenotoxic Effect of Nigella Sativa Oil

Objectives

Cyclophosphamide (CP) is an alkylating agent widely used as an antineoplastic and immunosuppressive agent. The genotoxicity of CP has been studied in a variety of in vivo and in vitro systems and is routinely used as a positive control in genotoxicity tests. Traditional medicine Nigella sativa L., (N. sativa), Ranunculaceae family, especially in the Eastern Mediterranean countries, especially in many countries, and is widely used in many countries as a spice and folk medicine since the time of Dioscorides used as a plant. In this study, it was aimed to show the protective effects of N. sativa oil at different concentrations against the genotoxic effects of CP by micronucleus test.

Materials and Methods

For this purpose, healthy cells were treated in vitro with N. sativa oil at concentrations of 1, 5, 10 μg/mL and CP as positive control for 68 hours. The micronuclei were then counted.

Results

No significant increase in micronucleus frequency was observed when the application of N. sativa oil at concentrations of 1, 5, 10 μg/mL compared with the negative control. There was a decrease in the number of micronucleus in all three concentrations (1, 5, 10 μg/mL) compared to the CP group in the groups treated with N. sativa oil and CP.

Conclusion

It has been shown that N. sativa oil may have protective effects against genotoxicity agents in vitro. But more work is needed to understand the mechanism of the genotoxicity effects of N. sativa oil.