Ocularpreparations: the formulation approach

Author(s): Kaur IP, Kanwar M


The main aim of pharmacotherapeutics is the attainment of an effective drug concentration at the intended site of action for a sufficient period of time to elicit the response. A major problem being faced in ocular therapeutics is the attainment of an optimal concentration at the site of action. Poor bioavailability of drugs from ocular dosage forms is mainly due to the tear production, non-productive absorption, transient residence time, and impermeability of corneal epithelium. This article reviews: the barriers that decrease the bioavailability of an ophthalmic drug; the objectives to be considered in producing optimal formulations; and the approaches being used to improve the corneal penetration of a drug molecule and delay its elimination from the eye. The focus of this review is on the recent developments in topical ocular drug delivery systems, the rationale for their use, their drug release mechanism, and the characteristic advantages and limitations of each system. In addition, the review attempts to give various analytical procedures including the animal models and other models required for bioavailability and pharmacokinetic studies. The latter can aid in the design and predictive evaluation of newer delivery systems.

The dosage forms are divided into the ones which affect the precorneal parameters, and those that provide a controlled and continuous delivery to the pre- and intraocular tissues. The systems discussed include: (a) the commonly used dosage forms such as gels, viscosity imparting agents, ointments, and aqueous suspensions; (b) the newer concept of penetration enhancers, phase transition systems, use of cyclodextrins to increase solubility of various drugs, vesicular systems, and chemical delivery systems such as the prodrugs; (c) the developed and under-development controlled/continuous drug delivery systems including ocular inserts, collagen shields, ocular films, disposable contact lenses, and other new ophthalmic drug delivery systems; and (d) the newer trends directed towards a combination of drug delivery technologies for improving the therapeutic response of a non-efficacious drug. The fruitful resolution of the above-mentioned technological suggestions can result in a superior dosage form for both topical and intraocular ophthalmic application.

Similar Articles

Drug delivery to the posterior segment of the eye

Author(s): Lee TWY, RobinsonJR

Development andevaluation of prolonged release topical indomethacin formulations for ocularinflammation

Author(s): AdelliGR, Balguri SP, Punyamurthula N, Bhagav P, Majumdar S

Theblood-ocular barriers

Author(s): Cunha-Vaz J

Drug delivery to the retina: challenges and opportunities

Author(s): Duvvuri S,Majumdar S, Mitra AK

Evaluation of topical hesperetin matrix filmfor back-of-the-eye delivery

Author(s): Adelli GR, Hingorani T, PunyamurthulaN, Balguri SP, Majumdar S

Ocular inserts - Advancement in therapy of eye diseases

Author(s): Kumari A, Sharma PK, Garg VK,Garg G

Ocular inserts for topical delivery

Author(s): SaettoneFM, Salminen L

Stability of benzocaine formulated in commercialoral disintegrating tablet platforms

Author(s): Köllmer M, Popescu C, Manda P,Zhou L, Gemeinhart RA

New methods of drug delivery

Author(s): Langer R

Iontophoretic drug delivery for the treatment ofscars

Author(s): Manda P, Angamuthu M, HiremathSR, Raman V, Murthy SN

Polysulfone capillary fiber forintraocular drug delivery: in vitro and in vivo evaluations

Author(s): Rahimy MH, PeymanGA, Chin SY, Golshani R, Aras C, et al.

Intravitreal sustained-releaseganciclovir

Author(s): Smith TJ, Pearson PA, BlandfordDL, Brown JD, Goins KA, et al.

Delivery of cefotaxime to the brain viaintranasal administration

Author(s): Manda P, Hargett JK, Kiran Vaka SR,Repka MA, Narasimha Murthy S

Biodegradable Intrascleral Implant for SustainedIntraocular Delivery of Betamethasone Phosphate

Author(s): Okabe J, Kimura H, Kunou N, OkabeK, Kato A, et al.

Delivery of ziconotide to cerebrospinalfluid via intranasal pathway for the treatment of chronic pain

Author(s): Manda P, Kushwaha AS, Kundu S,Shivakumar H, Jo SB, et al.

Episcleral implants for topotecandelivery to the posterior segment of the eye

Author(s): Carcaboso AM, Chiappetta DA,Opezzo JA, Höcht C, Fandiño AC, et al.