Nanomedicine is increasingly becoming important in the treatment of diseases and diagnosis. Size of the particle plays an important role. As the particle size decreases its effect to cure the disease increases. Pharmacokinetics, bioavailability, half-life, metabolism, biodistribution and permeability of nanomedicine were found to be better than that of microsized drugs. In vitro and In vivo ADME (Absorption, Distribution, Metabolism and Excretion) studies are mandatory for pharmaceutical organic drugs. Similarly, nanomaterials should be subjected to both in vitro and in vivo ADME studies. Thus, nanomedicine can assist in the development of safe personalized medicine in humans.

Silver nanoparticles have many medical and commercial applications, but their effects on human health are poorly understood. They are used extensively in products of daily use, but little is known about their potential neurotoxic effects. A xenobiotic metal, silver, has no known physiological significance in the human body as a trace metal. Biokinetics of silver nanoparticles indicates its elimination from the body via urine and feces route. However, a substantial amount of evidence from both in vitro and in vivo experimental research unequivocally establish the fact of easier penetration of smaller nanoparticles across the blood–brain barrier to enter in brain and thereby interaction with cellular components to induce neurotoxic effects. Toxicological effects of silver nanoparticles rely on the degree of exposure, particle size, surface coating, and agglomeration state as well as the type of cell or organism used to evaluate its toxicity. This review covers pertinent facts and the present state of knowledge about the neurotoxicity of silver nanoparticles reviewing the impacts on oxidative stress, neuroinflammation, mitochondrial function, neurodegeneration, apoptosis, and necrosis. The effect of silver nanoparticles on the central nervous system is a topic of growing interest and concern that requires immediate consideration.

Background: Nanomedicine is increasingly used to treat various ailments. Biocompatibility of nanomedicine is primarily governed by its properties such as bioavailability, biotransformation and biokinetics. One of the major advantages of nanomedicine is enhanced bioavailability of drugs. Biotransformation of nanomedicine is important to understand the pharmacological effects of nanomedicine. Biokinetics includes both pharmacokinetics and toxicokinetics of nanomedicine. Physicochemical parameters of nanomaterials have extensive influence on bioavailability, biotransformation and biokinetics of nanomedicine. Method: We carried out a structured peer-reviewed research literature survey and analysis using bibliographic databases. Results: Eighty papers were included in the review. Papers dealing with bioavailability, biotransformation and biokinetics of nanomedicine are found and reviewed. Bioavailability and biotransformation along with biokinetics are three major factors that determine the biological fate of nanomedicine. Extensive research work has been done for drugs of micron size but studies on nanomedicine are scarce. Therefore, more emphasis in this review is given on the bioavailability and biotransformation of nanomedicine along with biokinetics. Conclusion: Bioavailability results based on various nanomedicine are summarized in the present work. Biotransformation of nanodrugs as well as nanoformulations is also the focus of this article. Both in vitro and in vivo biotransformation studies on nanodrugs and its excipients are necessary to know the effect of metabolites formed. Biokinetics of nanomedicine is captured in details that are complimentary to bioavailability and biotransformation. Nanomedicine has the potential to be developed as a personalized medicine once its physicochemical properties and its effect on biological system are well understood.

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Androstenedione (AD) is a steroid intermediate valuable for the production of steroid medicaments. Microbial biotransformation of phytosterol to produce AD is a wellresearched area. However, low substrate solubility of phytosterol in aqueous media and nucleus degradation of AD to androstadienedione (ADD) or 9-hydroxy-AD are the major obstacles for AD production leading to detailed research for optimization of biotransformation process. In this review, microbial transformation of AD with respect to the existing methods of chemical or biochemical synthesis of AD are extensively discussed. This review examines the microbial biotransformation process and limitations for enhanced AD production. Factors affecting the effective biotransformation process to obtain AD are discussed and limitations are highlighted. The main content of this review focuses on the recent and futuristic biotechnological advances and strategies in techniques to enhance AD bioprocess.