Evaluation of soluble Bioadhesive Ophthalmic Drug Inserts (BODI) for prolonged release of gentamicin: lachrymal pharmacokinetics and ocular tolerance

New Trends in Drug Delivery Systems for Veterinary Applications

BACKGROUND

The veterinary pharmaceutical industry has shown significant growth in recent decades. Several factors contribute to this increase as the demand for the improvement of the quality of life of both domestic and wild animals, together with the need to improve the quality, productivity, and safety of foodstuffs of animal origin.

METHODS

The goal of this work was to identify the most suitable medicines for animals that focus on drug delivery routes as those for humans, although they may have different devices, such as collars and ear tags.

RESULTS

Recent advances in drug delivery systems for veterinary use are discussed, both from academic research and the global market. The administration routes commonly used for veterinary medicines are also explored, while special attention is given to the latest technological trends to improve the drug performance, reducing the number of doses, animal stress, and side effects.

CONCLUSION

Drug delivery system in veterinary decreased the number of doses, side effects, and animal stress that are a small fraction of the benefits of veterinary drug delivery systems and represent a significant increase in profit for the industry; also, it demands investments in research regarding the quality, safety, and efficacy of the drug and the drug delivery systems.

Water dispersible microbicidal cellulose acetate phthalate film

Background

Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production.

Methods

CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined.

Results

The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold.

Conclusions

Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP.

Melt extrusion: from process to drug delivery technology

Starting from the plastic industry, today melt extrusion has found its place in the array of pharmaceutical manufacturing operations. This article reviews the process technology with regard to the set up and specific elements of the extruder as well as its application. Melt extrusion processes are currently applied in the pharmaceutical field for the manufacture of a variety of dosage forms and formulations such as granules, pellets, tablets, suppositories, implants, stents, transdermal systems and ophthalmic inserts. As a specific area the manufacture of solid dispersions, in particular, solid molecular dispersions using the melt extrusion process is reviewed. Melt extrusion is considered to be an efficient technology in this field with particular advantages over solvent processes like co-precipitation. Potential drawbacks like the influence of heat stress and shear forces on the drug active have been overcome in a number of examples with drugs of different chemical structure. Examples of suitable excipients and recent findings like self-emulsifying preparations are presented. The article concludes with a number of published examples of melt extrudates applying the principle of solid molecular dispersions. Improved bioavailability was achieved again demonstrating the value of the technology as a drug delivery tool.

Delivery of antibiotics to the eye using a positively charged polysaccharide as vehicle

The positively charged polysaccharide chitosan is able to increase precorneal residence time of ophthalmic formulations containing active compounds when compared with simple aqueous solutions. The purpose of the study was to evaluate tear concentration of tobramycin and ofloxacin after topical application of chitosan-based formulations containing 0.3% wt/vol of antibiotic and to compare them with 2 commercial solutions: Tobrex and Floxal, respectively. The influence of the molecular weight, deacetylation degree, and concentration of 4 different samples of chitosan on pharmacokinetic parameters (area under the curve values [AUC(eff)] and time of efficacy [t(eff)]) of tobramycin and ofloxacin in tears was investigated over time. It was demonstrated that the 2 chitosan products of high molecular weight (1350 and 1930 kd) and low deacetylation degree (50%) significantly increased antibiotic availability when compared to the controls, with AUC(eff) showing a 2- to 3-fold improvement. The time of efficacy of ofloxacin was significantly increased from about 25 minutes to 46 minutes by the chitosan of higher Mw (1930 kd) at a concentration of 0.5% wt/vol, whereas a similar performance was achieved by a chitosan of low Mw (580 kd) at a concentration of 1.5% wt/vol in the case of tobramycin.

Ocular effects of adrenomedullin

The purpose of this study was to determine the expression and effects of adrenomedullin (AM), a novel vasodilator peptide, in the eye. Expression of AM mRNA was examined in the rat iris-ciliary body using reverse transcription-polymerase chain reaction (RT-PCR). In rabbits, intraocular pressure (IOP) was measured periodically after intravitreal injection (20 microl) of AM (10(-7)-10(-4)m) into one eye. In separate groups of rabbits, 30 min after intravitreal injection of either AM-(22-52) (10(-3)m), a specific AM receptor antagonist, or CGRP-(8-37) (10(-3)m), a CGRP1 receptor antagonist, into one eye, AM (10(-6)m) was injected into both eyes, and IOP was measured. Using different rabbits, aqueous protein and cAMP concentrations were determined 6 hr after injection of AM. Expression of AM mRNA was detected in the rat iris-ciliary body. In rabbits, intravitreally administered AM (10(-6)-10(-4)m) profoundly lowered IOP, and the maximum effect was observed at 4-8 h. The ocular hypotensive effect of AM was dose-dependent (10(-7)-10(-4)m). Pretreatment with CGRP-(8-37) did not significantly inhibit the ocular hypotensive effect of AM (10(-6)m), whereas pretreatment with AM-(22-52) completely abolished it. AM (10(-6)m) did not significantly affect aqueous protein concentration. The higher dose of AM (10(-5)m) induced a significant increase in aqueous protein, which was not associated with an increase in the aqueous cAMP content and was significantly inhibited by AM-(22-52) and CGRP-(8-37). These results demonstrate that AM is expressed in the iris-ciliary body and decreases IOP mainly via specific AM receptors, and suggest that AM may play a role in controlling IOP.