This paper describes hitherto developed drug forms for topical ocular administration, that is, eye drops, ointments, in situ gels, inserts, multicompartment drug delivery systems, and ophthalmic drug forms with bioadhesive properties. Heretofore, many studies have demonstrated that new and more complex ophthalmic drug forms exhibit advantage over traditional ones and are able to increase the bioavailability of the active substance by, among others, reducing the susceptibility of drug forms to defense mechanisms of the human eye, extending contact time of drug with the cornea, increasing the penetration through the complex anatomical structure of the eye, and providing controlled release of drugs into the eye tissues, which allows reducing the drug application frequency. The rest of the paper describes recommended in vitro and in vivo studies to be performed for various ophthalmic drugs forms in order to assess whether the form is acceptable from the perspective of desired properties and patient's compliance.

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Ophthalmic Drug Dosage Forms: Characterisation and Research Methods

Various strategies for ocular drug delivery are considered; from basic formulation techniques for improving availability of drugs; viscosity enhancers and mucoadhesives aid drug retention and penetration enhancers promote drug transport into the eye. The use of drug-loaded contact lenses and ocular inserts allows drugs to be better placed where they are needed for more direct delivery. Developments in ocular implants gives a means to overcome the physical barriers that traditionally prevented effective treatment. Implant technologies are under development allowing long-term drug delivery from a single procedure, these devices allow posterior chamber diseases to be effectively treated. Future developments could bring artificial corneas to eliminate the need for donor tissue and one-off implantable drug depots lasting the patient's lifetime.

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Advances in ophthalmic drug delivery.

Peptic ulcer is among the most serious gastrointestinal diseases in the world. Several orthodox drugs are employed for the treatment of the disease. Although these drugs are effective, they produce many adverse effects thus limiting their use. In recent years, there has been a growing interest in alternative therapies, especially those from plants due to their perceived relative lower side effects, ease of accessibility, and affordability. Plant medicines with ethnomedicinal use in peptic ulcer management need to be screened for their effectiveness and possible isolation of lead compounds. This requires use of appropriate animal models of various ulcers. The limited number of antiulcer models for drug development against gastric and duodenal ulcer studies has hindered the progress of targeted therapy in this field. It is, therefore, necessary to review the literature on experimental models used to screen agents with potential antigastroduodenal ulcer activity and explain their biochemical basis in order to facilitate their use in the development of new preventive and curative antiulcer drugs. Clinical trials can then be carried out on agents/drugs that show promise. In this paper, current in vivo animal models of ulcers and the pathophysiological mechanisms underlying their induction, their limitations, as well as the challenges associated with their use have been discussed.

/pdf/in-vivo-models-used-for-evaluation-of-potential-4le9q3lik6.pdf

In Vivo Models Used for Evaluation of Potential Antigastroduodenal Ulcer Agents

The field of encapsulation, especially microencapsulation, is a rapidly growing area of research and product development. The Handbook of Encapsulation and Controlled Release covers the entire field, presenting the fundamental processes involved and exploring how to use those processes for different applications in industry. Written at a level comp

Handbook of Encapsulation and Controlled Release

The influences of the serotonergic system on dopamine (DA) neuron activity have received considerable attention during the last three decades due to the real opportunity to improve disorders related to central DA neuron dysfunctions such as Parkinson’s disease, schizophrenia, or drug abuse with serotonergic drugs. Numerous biochemical and behavioral data indicate that serotonin (5-HT) affects dopaminergic terminal function in the striatum. The authors propose a thorough examination of data showing controversial effects induced by striatal 5-HT on dopaminergic activity. Inhibitory and excitatory effects of exogenous 5-HT have been reported on DA release and synthesis, involving various striatal 5-HT receptors. 5-HT also promotes an efflux of DA through reversal of the direction of DA transport. By analogy with the mechanism of action described for amphetamine, the consequences of 5-HT entering DA terminals might explain both the excitatory and inhibitory effects of 5-HT on presynaptic DA terminal activity, but the physiological relevance of this mechanism is far from clear. The recent data suggest that the endogenous 5-HT system affects striatal DA release in a state-dependent manner associated with the conditional involvement of various 5-HT receptors such as 5-HT2A, 5-HT2C, 5-HT3, and 5-HT4 receptors. Methodological and pharmacological issues have prevented a comprehensive overview of the influence of 5-HT on striatal DA activity. The distribution of striatal 5-HT receptors and their restricted influence on DA neuron activity suggest that the endogenous 5-HT system exerts multiple and subtle influences on DA-mediated behaviors.

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Presynaptic control of serotonin on striatal dopamine function

The present study appraised the hepatoprotective activity of aqueous extract of Camellia sinensis leaves 10 and its possible mechanism of action. Liver damage was induced by intraperitoneal administration of car11 bon tetrachloride/olive oil (50 % v/v, 0.5 ml/kg ) in male Wistar rats (150-220g) once daily for 7 days and 12 the extent of damage was studied by assessing biochemical parameters such as alanine amino trans13 ferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), total protein and albumin 14 in serum and concentrations of lipid peroxides (LPO), glutathione (GSH), catalase (CAT) and superoxide 15 dismutase (SOD) in liver. The aqueous extract of Camellia sinensis (100 mg and 200 mg/Kg) were ad16 ministered orally to the animals with hepatotoxicity induced by carbon tetrachloride and its effects on bio17 chemical parameters were compared with those in animals treated with vitamin E (100 mg/Kg). Histopa18 thological studies were also done. Camellia sinensis 100 and 200mg/kg results in significant reduction in 19 serum hepatic enzymes and liver lipid peroxide which were increased by carbon tetrachloride. There was 20 significant increase in serum total protein, albumin and liver GSH, SOD and CAT when compared to 21 those in rats treated by carbon tetrachloride. The antioxidant activity of Camellia sinensis (100 and 22 200mg/Kg) were comparable with the effects of vitamin E (100mg/Kg). Histopathological changes (con23 gestion of central vein, centrilobular necrosis and sinusoidal congestion) induced by carbon tetrachloride 24 were reduced to a moderate extent in Camellia-sinensis-treated rats. Taking together, Camellia sinensis 25 protectes the liver from carbon-tetrachloride-induced damage. Probable mechanism of its action is its 26 anti-oxidant property. 27

Possible Mechanism of Action

Ocular diseases require localized administration of drugs to the tissues around the ocular cavity. The existing ocular drug delivery systems are fairly primitive and inefficient. However, the design of ocular system is undergoing gradual transition from an empirical to rational basis. In the recent years, there has been explosion of interest in the polymer based delivery devices. Utilization of the principles of controlled release as embodied by ocular inserts offers an attractive approach to the problem of prolonging pre-corneal drug residence times. In the present update, the authors discuss the basic concept of ocular inserts as drug delivery system and examine the few inserts, which are available in the market or are being developed by pharmaceutical companies for drug delivery.The article discusses soluble ocular drug insert (SODI), Ocusert, Collagen Shields, Ocufit, Minidisc and new ophthalmic delivery system (NODS) with special attention to biological/clinical performances, and potential for future applications and developments.

The concept of ocular inserts as drug delivery systems: An overview

Th e present study appraised the hepatoprotective activity of aqueous extract of Trianthema decandra roots against carbon tetrachlorideinduced liver damage. Liver damage was induced by intraperitoneal administration of an equal mixture of carbon tetrachloride and olive oil (50% v/v, 0.5 ml/kg) in male Wistar rats (150-220 g) once daily for 7 days and the extent of damage was studied by assessing the biochemical parameters such as alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), total protein and albumin in serum. Th e aqueous extract of Trianthema decandra roots (50 mg, 100 mg and 200 mg/kg) were orally administered to the animals with hepatotoxicity induced by carbon tetrachloride and its eff ects on biochemical parameters were compared with Silymarin (25 mg/kg) treated animals. Trianthema decandra (100 and 200 mg/kg) results in a signifi cant reduction in serum hepatic enzymes when compared to rats treated with carbon tetrachloride alone. Th ere was a signifi cant increase in the serum total protein and albumin when compared to rats treated with carbon tetrachloride alone. Th e results concludes that the aqueous extract of Trianthema decandra roots (100 and 200 mg/kg) has protected the liver from carbon tetrachloride-induced damage. Key words: Carbon tetrachloride, hepatoprotective and silymarin, Trianthema decandra

Hepatoprotective activity of Trianthema decandra on carbon tetrachloride-induced hepatotoxicity in rats

The present study appraised the hepatoprotective activity of aqueous extract of Camellia sinensis leaves and its possible mechanism of action against carbon-tetrachloride-induced liver damage. Liver damage was induced by intraperitoneal administration of equal mixture of carbon tetrachloride and olive oil (50 % v/v, 0.5 ml/kg ) in male Wistar rats (150-220g) once daily for 7 days and the extent of damage was studied by assessing biochemical parameters such as alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), total protein and albumin in serum and concentrations of lipid peroxides (LPO), glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) in liver . The aqueous extract of Camellia sinensis (100 mg and 200 mg/Kg) were administered orally to the animals with hepatotoxicity induced by carbon tetrachloride and its effects on biochemical parameters were compared with Vitamin E (100 mg/Kg) treated animals. Histopathological studies of the experimental animal were also done. Camellia sinensis 100 and 200mg/kg results in significant reduction in serum hepatic enzymes and liver lipid peroxide which were increased by carbon tetrachloride. There was significant increase in serum total protein, albumin and liver GSH, SOD and CAT when compared to those in rats treated by carbon tetrachloride . The antioxidant activity of Camellia sinensis (100 and 200mg/Kg) were comparable with the effects of Vitamin E (100mg/Kg). Histopathological changes (congestion of central vein, centrilobular necrosis and sinusoidal congestion) induced by carbon tetrachloride were prevented to a moderate extent in Camellia-sinensis -treated rats. Taking together, Camellia sinensis protectes the liver from carbon-tetrachloride-induced damage. Probable mechanism of its action may be due to its anti-oxidant property .

Jothivel Nandhakumar

Papers

Possible Mechanism of Action

The concept of ocular inserts as drug delivery systems: An overview

Hepatoprotective activity of Trianthema decandra on carbon tetrachloride-induced hepatotoxicity in rats

Hepatoprotective activity of Camellia sinensis and its possible mechanism of action