Description

Neurological Disease

Description

Ketorolac (Ketorolac tromethamine, Toradol) is a non-selective COX inhibitor of COX-1 and COX-2 with IC50 of 1.23 μM and 3.50 μM, respectively.

Targets

IC₅₀

In Vitro

(R, S)-, (S)-, and (R)-Ketorolac inhibit both isoforms of COX in recombinant rat and human enzyme systems, and similar as inhibitors of rat COX (rCOX) and human COX (hCOX) under the conditions used. (R, S)-Ketorolac inhibits rat COX-1, rat COX-2, human COX-1 and human COX-2 with IC50 of 0.27 μM, 2.06 μM, 1.23 μM and 3.50 μM, respectively. The (S) enantiomer of Ketorolac with IC50 of 0.10 μM for rat COX-1 is approximately twice as potent as the racemate, whereas the (R)-enantiomer with IC50 of > 100 μM is virtually without activity. ^[1] Ketorolac shows inhibition of eicosanoid formation in HEL cells (COX-1) and LPS-stimulated Mono Mac 6 cells (COX-2) with IC50 of 0.025 μM and 0.039 μM, respectively, but does not significantly inhibit NO accumulation in supernatants of LPS-stimulated RAW 264.7 cells up to 300 μM. ^[2] Ketorolac significantly inhibits thymidine incorporation of human osteoblasts (hOBs) upon 24 hours treatment in a dose-dependent manner, and inhibits proliferation and arrests cell cycle at G0/G1 phase in hOBs. ^[3]

In Vivo

(R, S)-Ketorolac is significantly more potent than indomethacin or diclofenac sodium in tests of acetic acid-induced writhing, carrageenan-induced paw hyperalgesia, and carrageenan-induced edema formation in rats, with ID50 of 0.24, 0.29 and 0.08 mg/kg, respectively. ^[1] Ketorolac produces significant inhibition of COX-1 activity and gastric PG synthesis with doses of ≥1 mg/kg inhibiting COX-1 activity by 95% and gastric PG synthesis by >88%. Ketorolac does not significantly affect COX-2 activity at doses of ≤3 mg/kg, but at doses of 10 and 30 mg/kg, Ketorolac produces significant inhibition of COX-2 activity by 75% and 91%, respectively. Ketorolac causes gastric damage in rats only at doses that inhibits both COX-1 and COX-2, or when given with a COX-2 inhibitor. ^[4]

Clinical Trials

Phase IV has been completed in the study of disposition of intravenous Ketorolac after cesarean section.

Features

Ketorolac is a COX-1 preferential inhibitor of the currently marked nonsteroidal anti-inflammatory drugs (NSAIDs).

Inhibition of Prostaglandin Formation

Recombinant COX-1 and COX-2 from rat (rCOX) and human (hCOX) expressed in a baculovirus system are purified and reconstituted with 2 mM phenol and 1 μM hematin. Then the cyclooxygenase activity is measured using a radiometric assay, and the specific activity of the final enzyme preparations used is between 20,000 and 35,000 units. Ketorolac (2 -15 μL) are diluted in DMSO and preincubated with the appropriate recombinant COX (3 -15 ng) at a final concentration of 0.01 to 1000 μM in a reaction mixture (150 μL) containing 50 mM Tris-HCl buffer (pH 7.9), 2 mM EDTA, 10% glycerol, 2 mM phenol, and 1 μM hematin for 10 minutes. The reaction is initiated by addition of [¹⁴C]arachidonic acid (50–60 mCi/mmol in a final concentration of 20 μM) and is terminated 45 seconds later by the addition of 100 μL of 0.2 N HCl and 750 μL of distilled water. The total reaction volume is then applied to a 1 mL C₁₈ Sep-pak column that has previously been washed with 2 mL of methanol followed by 5 mL of deionized water. Oxygenated products are eluted with 3 mL of a mixture of acetonitrile/water/acetic acid (50:50:0.1, v/v/v) and quantified by liquid scintillation spectroscopy.

Cell Lines

Primary human osteoblasts cell lines

Concentrations

Dissolved in DMSO, final concentration ~0.1 mM

Incubation Time

24 hours

Methods

Human osteoblasts cells are exposed to Ketorolac for 24 hours. Thymidine incorporation is assessed by the TopCount Microplate Scintillation and Luminescence Counters through adding [³H]-thymidine to cultures 4 hours prior to harvesting. Cell cycle distribution is determined by using propidium iodide in flow cytometer, and cell apoptosis or necrosis is detected using the Annexin V-FITC Apoptosis Detection Kit.

Animal Models

Male Wistar rats

Formulation

Dissolved in DMSO and diluted in saline.

Doses

0.3-30 mg/kg

Administration

Take orally