Acular LS (Ketorolac Tromethamine Ophthalmic) - Description and Clinical Pharmacology

DESCRIPTION

ACULAR LS ^® (ketorolac tromethamine ophthalmic solution) 0.4% is a member of the pyrrolo-pyrrole group of nonsteroidal anti-inflammatory drugs (NSAIDs) for ophthalmic use.

Structural and Molecular Formula:

C₁₉H₂₄N₂O₆    Mol Wt 376.40

Chemical Name: (±)-5-Benzoyl-2,3-dihydro-1H-pyrrolizine-1-carboxylic acid, compound with 2-amino-2-(hydroxymethyl)-1,3-propanediol (1:1)

Contains:

Active: ketorolac tromethamine 0.4%.
Preservative: benzalkonium chloride 0.006%. Inactives: sodium chloride; edetate disodium 0.015%; octoxynol 40; purified water; and hydrochloric acid and/or sodium hydroxide to adjust pH.

ACULAR LS ^® ophthalmic solution is supplied as a sterile isotonic aqueous 0.4% solution, with a pH of approximately 7.4. ACULAR LS ^® ophthalmic solution is a racemic mixture of R-(+) and S-(-)- ketorolac tromethamine. Ketorolac tromethamine may exist in three crystal forms. All forms are equally soluble in water. The pKa of ketorolac is 3.5. This white to off-white crystalline substance discolors on prolonged exposure to light. The osmolality of ACULAR LS ^® ophthalmic solution is approximately 290 mOsml/kg.

CLINICAL PHARMACOLOGY

Mechanism of Action

Ketorolac tromethamine is a nonsteroidal anti-inflammatory drug which, when administered systemically, has demonstrated analgesic, anti-inflammatory, and anti-pyretic activity. The mechanism of its action is thought to be due to its ability to inhibit prostaglandin biosynthesis. Ketorolac tromethamine given systemically does not cause pupil constriction.

Pharmacokinetics

One drop (0.05 mL) of 0.5% ketorolac tromethamine ophthalmic solution was instilled into one eye and one drop of vehicle into the other eye TID in 26 normal subjects. Only 5 of 26 subjects had a detectable amount of ketorolac in their plasma (range 10.7 to 22.5 ng/mL) at day 10 during topical ocular treatment. When ketorolac tromethamine 10 mg is administered systemically every 6 hours, peak plasma levels at steady state are around 960 ng/mL.

Clinical Studies

In two double-masked, multi-centered, parallel-group studies, 313 patients who had undergone photorefractive keratectomy received ACULAR LS ^® 0.4% or its vehicle QID for up to 4 days. Significant differences favored ACULAR LS ^® for the reduction of ocular pain and burning/stinging following photorefractive keratectomy surgery.

Results from clinical studies indicate that ketorolac tromethamine has no significant effect upon intraocular pressure.

The safety and effectiveness of ACULAR LS ^® in post-cataract surgery patients has not been established.