Thakur Singh - Academia.edu (original) (raw)

Papers by Thakur Singh

European Polymer Journal, 2009

Drug Development and Industrial Pharmacy, 2009

Pharmaceutical Research, 2009

Methods In this study we determined, for the first time, the ability of microorganisms to travers... more Methods In this study we determined, for the first time, the ability of microorganisms to traverse microneedle-induced holes using two different in vitro models. Results When employing Silescol® membranes, the numbers of Candida albicans, Pseudomonas aeruginosa and Staphylococcus epidermidis crossing the membranes were an order of magnitude lower when the membranes were punctured by microneedles rather than a 21G hypodermic needle. Apart from the movement of C. albicans across hypodermic needle-punctured membranes, where 40.2% of the microbial load on control membranes permeated the barrier over 24 h, the numbers of permeating microorganisms was less than 5% of the original microbial load on control membranes. Experiments employing excised porcine skin and radiolabelled microorganisms showed that the numbers of microorganisms penetrating skin beyond the stratum corneum were approximately an order of magnitude greater than the numbers crossing Silescol® membranes in the corresponding experiments. Approximately 103 cfu of each microorganism adhered to hypodermic needles during insertion. The numbers of microorganisms adhering to MN arrays were an order of magnitude higher in each case. Conclusion We have shown here that microneedle puncture resulted in significantly less microbial penetration than did hypodermic needle puncture and that no microorganisms crossed the viable epidermis in microneedle—punctured skin, in contrast to needle-punctured skin. Given the antimicrobial properties of skin, it is, therefore, likely that application of microneedle arrays to skin in an appropriate manner would not cause either local or systemic infection in normal circumstances in immune-competent patients. In supporting widespread clinical use of microneedle-based delivery systems, appropriate animal studies are now needed to conclusively demonstrate this in vivo. Safety in patients will be enhanced by aseptic or sterile manufacture and by fabricating microneedles from self-disabling materials (e.g. dissolving or biodegradable polymers) to prevent inappropriate or accidental reuse.

Nitric Oxide-biology and Chemistry, 2009

Naunyn-schmiedebergs Archives of Pharmacology, 2010

The present study has been designed to investigate the role of opioid receptors, mast cells, and ... more The present study has been designed to investigate the role of opioid receptors, mast cells, and histamine receptors (H1 subtype) in the seizurogenic effect of tramadol on pentylenetetrazole-treated mice. A single injection of pentylenetetrazole (80 mg kg−1) was used to elicit seizure activity in mice. Seizures were assessed in terms of the time latency of the onset of Straub-like tail, onset of jerky movements of whole body, convulsions, and death. Tramadol administration (50 mg kg −1) caused a marked increase in seizurogenic activity of pentylenetetrazole as measured in terms of a significant decrease in the time latency of the onset of Straub-like tail, jerky movements of whole body, convulsions, and death. Moreover, prior administration of naloxone (2 mg kg−1), fexofenadine (100 mg kg−1), cetrizine, sodium cromoglycate, and ketotifen (10 mg kg−1), respectively, attenuated the seizurogenic activity that tramadol exerted on pentylenetetrazole-treated mice. Therefore, it may be suggested that tramadol exerts a seizurogenic effect on mice via an H1 receptor activation-linked pathway possibly through an opioid receptor-dependent release of histamine from the mast cells.

European Polymer Journal, 2009

Drug Development and Industrial Pharmacy, 2009

Pharmaceutical Research, 2009

Methods In this study we determined, for the first time, the ability of microorganisms to travers... more Methods In this study we determined, for the first time, the ability of microorganisms to traverse microneedle-induced holes using two different in vitro models. Results When employing Silescol® membranes, the numbers of Candida albicans, Pseudomonas aeruginosa and Staphylococcus epidermidis crossing the membranes were an order of magnitude lower when the membranes were punctured by microneedles rather than a 21G hypodermic needle. Apart from the movement of C. albicans across hypodermic needle-punctured membranes, where 40.2% of the microbial load on control membranes permeated the barrier over 24 h, the numbers of permeating microorganisms was less than 5% of the original microbial load on control membranes. Experiments employing excised porcine skin and radiolabelled microorganisms showed that the numbers of microorganisms penetrating skin beyond the stratum corneum were approximately an order of magnitude greater than the numbers crossing Silescol® membranes in the corresponding experiments. Approximately 103 cfu of each microorganism adhered to hypodermic needles during insertion. The numbers of microorganisms adhering to MN arrays were an order of magnitude higher in each case. Conclusion We have shown here that microneedle puncture resulted in significantly less microbial penetration than did hypodermic needle puncture and that no microorganisms crossed the viable epidermis in microneedle—punctured skin, in contrast to needle-punctured skin. Given the antimicrobial properties of skin, it is, therefore, likely that application of microneedle arrays to skin in an appropriate manner would not cause either local or systemic infection in normal circumstances in immune-competent patients. In supporting widespread clinical use of microneedle-based delivery systems, appropriate animal studies are now needed to conclusively demonstrate this in vivo. Safety in patients will be enhanced by aseptic or sterile manufacture and by fabricating microneedles from self-disabling materials (e.g. dissolving or biodegradable polymers) to prevent inappropriate or accidental reuse.

Nitric Oxide-biology and Chemistry, 2009

Naunyn-schmiedebergs Archives of Pharmacology, 2010

The present study has been designed to investigate the role of opioid receptors, mast cells, and ... more The present study has been designed to investigate the role of opioid receptors, mast cells, and histamine receptors (H1 subtype) in the seizurogenic effect of tramadol on pentylenetetrazole-treated mice. A single injection of pentylenetetrazole (80 mg kg−1) was used to elicit seizure activity in mice. Seizures were assessed in terms of the time latency of the onset of Straub-like tail, onset of jerky movements of whole body, convulsions, and death. Tramadol administration (50 mg kg −1) caused a marked increase in seizurogenic activity of pentylenetetrazole as measured in terms of a significant decrease in the time latency of the onset of Straub-like tail, jerky movements of whole body, convulsions, and death. Moreover, prior administration of naloxone (2 mg kg−1), fexofenadine (100 mg kg−1), cetrizine, sodium cromoglycate, and ketotifen (10 mg kg−1), respectively, attenuated the seizurogenic activity that tramadol exerted on pentylenetetrazole-treated mice. Therefore, it may be suggested that tramadol exerts a seizurogenic effect on mice via an H1 receptor activation-linked pathway possibly through an opioid receptor-dependent release of histamine from the mast cells.