Monday, February 6, 2012

Ofloxacin Evaluation

Ofloxacin Evaluation

Most ocular treatments like eye drops and suspensions call for the topical administration of ophthalmically active drugs to the tissues around the ocular cavity. These dosage forms are easy to instill but suffer from the inherent drawback that the majority of the medication they contain is immediately diluted in the tear film as soon as the eye drop solution is instilled into the culde-sac and is rapidly drained away from the precorneal cavity by constant tear flow and lacrimo-nasal drainage.
The eye as a portal for drug delivery is generally used for local therapy against systemic therapy in order to avoid the risk of eye damage from high blood concentrations of the drug, which is not intended. The unique anatomy, physiology and biochemistry of the eye render this organ impervious to foreign substances, thus presenting a constant challenge to the formulator to circumvent the protective barriers of the eye without causing permanent tissue damage [‎ 1].
Therefore, only a very small fraction of the instilled dose is absorbed by the target tissue for this reason, concentrated solutions and frequent dosing are required
for the instillation to achieve an adequate level of therapeutic effect. One of the new classes of drug delivery systems, ocular inserts, which are gaining worldwide praise, release drugs at a pre-programmed rate for a longer period by increasing the precorneal residence time [‎ 2-‎ 4].
Ofloxacin is a pale yellow or bright yellow, crystalline powder. Ofloxacin is antibacterial and is the most commonly used fluroquinolone. It inhibits the enzyme bacterial DNA gyrase, which nicks double stranded DNA, introduces negative supercoils and then reseals the nicked ends. This is necessary to prevent excessive positive supercoiling of the strands when they separate to permit replication or transcription. The bactericidal action probably results from digestion of DNA by exonucleases whose production is signaled by the damaged DNA
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Bioelectronic DNA detection involves forming an electronic circuit mediated by nucleic acid hybridization and it serves as the basis for a DNA detection system called eSensor™ [1-4]. This system uses low-density DNA chips containing electrodes coated with DNA capture probes. Target DNA present in the sample hybridizes specifically both to capture probes and ferrocene labeled signal probes in solution thereby generating an electric current. Currente Sensor DNA chips contain as many as 36 electrodes for simultaneous detection of multiple pathogens from a single sample.

Many pathogens cause both acute and chronic disease at relatively low copy number and may be difficult or impossible to propagate in culture. Thus, most pathogen detection systems rely on nucleic acid amplification by using polymerase chain reaction (PCR). One highly effective amplification strategy targets conserved sequences among the family of organisms of interest. Such broad-range PCR strategies have been used to identify and characterize several known and previously uncharacterized bacteria [5,6] and viruses [7,8]. In order to maximize the utility of these effective pathogen nucleic acid amplification systems, amplification needs to be coupled with rapid, sensitive, and specific detection. Bioelectronic DNA detection by use of the eSensor chip might fulfill this need.

Human papillomaviruses (HPV) serve as an ideal model system for determining the efficiency and feasibility of eSensor DNA detection technology since there are at least 30 distinct genital HPV types that can be effectively amplified with broad-range consensus PCR primers. We designed two eSensor chips, each containing 14 probes specific for the conserved L1 region of the HPV genome. We evaluated clinical cervical cytology samples known to contain one or more HPV types. The eSensor DNA detection platform successfully detected the correct HPV type in most of these clinical samples, demonstrating that the system provides a rapid, sensitive, specific, and economical approach for multiple-pathogen detection and identification from a single sample.Background We used human papillomaviruses (HPV) as a model system to evaluate the utility of a nucleic acid, hybridization-based bioelectronic DNA detection platform (eSensor) in identifying multiple pathogens.