Shoreline

Arthrotec is an older NSAID, It is not in the same class of drugs as Viox, Celebrex or Bextra, It's closer to Ibuprophen and Naproxen , however it has an added ingredient, the Misoprotol, elps prevent gstric bleeds and other GI symptoms by increasing mucus to protect the stomach lining and decreasing the PH of specific gastric acids.

Diclofenac and Misoprostol
Diclofenac sodium is a nonsteroidal anti-inflammatory drug (NSAID). In pharmacologic studies, diclofenac sodium has shown anti-inflammatory, analgesic and antipyretic properties. The mechanism of action of diclofenac sodium, like other NSAIDs, is not completely understood but may be related to prostaglandin synthetase inhibition.

Diclofenac sodium is completely absorbed from the GI tract after fasting, oral administration. The diclofenac sodium in ARTHROTEC is in a pharmaceutical formulation that resists dissolution in the low pH of gastric fluid but allows a rapid release of drug in the higher pH environment of the duodenum. Only 50% of the absorbed dose is systemically available due to first pass metabolism. Peak plasma levels are achieved in 2 hours (range 1-4 hours), and the area under the plasma concentration curve (AUC) is dose proportional within the range of 25 mg to 150 mg. Peak plasma levels are less than dose proportional and are approximately 1.5 and 2.0 mcg/mL for 50 mg and 75 mg doses, respectively.

Plasma concentrations of diclofenac sodium decline from peak levels in a biexponential fashion, with the terminal phase having a half-life of approximately 2 hours. Clearance and volume of distribution are about 350 mL/min and 550 mL/kg, respectively. More than 99% of diclofenac sodium is reversibly bound to human plasma albumin.
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Pharmacodynamics and pharmacokinetics of misoprostol
Misoprostol is a synthetic prostaglandin E 1 analog with gastric antisecretory and (in animals) muscosal protective properties. NSAIDs inhibit prostaglandin synthesis. A deficiency of prostaglandins within the gastric and duodenal mucosa may lead to diminishing bicarbonate and mucus secretion and may contribute to the mucosal damage caused by NSAIDs.

Misoprostol can increase bicarbonate and mucus production, but in humans this has been shown at doses 200 mcg and above that are also antisecretory. It is therefore not possible to tell whether the ability of misoprostol to prevent gastric and duodenal ulcers is the result of its antisecretory effect, its mucosal protective effect, or both.

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Special warning, this should not be used if there is any chance of pregnancy occuring during trteatment with Arthrotec. It may have significant effects on the unborn fetus causing gross malformation of the fetus.
***Highest risk catagory for pregnanacy.***

It's souped up Motrin with something to protect the stomach, commonly used for OA and RA or other inflamatory conditions. Short half life requires repeat dosing , not a drug that has to build up in your system for weeks before any results are seen.
Hope this helps.
Dave