In the largest study of its kind to date, researchers at Medco report thatPPIs inhibit the effectiveness of clopidogrel, the number two prescriptiondrug in the world, thus increasing the risk of a major cardiac event, such asheart attacks and strokes by 50 percent. Since PPIs mimic the effect of avariant gene, which also renders clopidogrel ineffective, this study furthersuggests a potential role for genetic testing.

"Considering the widespread use of these two medications, this importantresearch adds to a growing body of evidence raising questions about theirconcurrent use and suggests further research is needed," said Dr. RobertEpstein, a lead study author, chief medical officer, Medco. "With thisresearch in hand, we intend to open a dialogue with the major clinicalorganizations to advance the discussion around the guidelines that govern theuse of Plavix."

Study details

Researchers tracked 16,690 patients who had undergone a percutaneouscoronary intervention such as stent placement or balloon angioplasty, and hadstarted taken clopidogrel as maintenance therapy. Of the patients in thestudy, 9,862 patients were taking clopidogrel alone; and 6,828 patients weretaking clopidogrel and a PPI. Researchers tracked the two groups in the studyfor a 12-month period using medical and pharmacy claims data.

Results of the study were striking: researchers reported that the relativerisk of a major adverse cardiovascular event was 50 percent higher, and therelative risk of a heart attack specifically was 74 percent higher, inpatients taking both medications together. The incidence of a majorcardiovascular event within 12 months of starting clopidogrel was 25 percentfor patients taking both medications concurrently. The study was funded solelyby Medco.

Genetic variability and clopidogrel:

For clopidogrel to work, it must first be converted to its active form bya liver enzyme called cytochrome P450 2C19. PPIs interfere with this enzymereducing the amount of clopidogrel that is converted to an active form. Thegene that produces this enzyme can vary such that individuals can have more orless enzyme activity, thus affecting its functionality. The way PPIs interferewith the conversion of clopidogrel to an active form may mimic this geneticvariation that produces lower amounts of the enzyme, suggesting that genetictesting for this enzyme may be useful. Other studies have shown that as manyas 30 percent of people worldwide are born with this particular geneticvariation.

Alerting physicians to potential risk for patients

Based upon this and other research on the issue, Medco will begin alertingprescribing physicians through a range of communications via its MedcoTherapeutic Resource Centers (R) and other channels so that prescribers canreconsider the risk/benefit of concurrent prescribing of clopidogrel and PPIsbased on their patients individual circumstances.

Medco will also communicate its findings to various clinical organizationsto encourage continued dialogue around prescribing guidelines for these twomedications. Medco's researchers plan to provide the findings to the Food andDrug Administration (FDA) as part of their recently announced researchcollaboration in the area of pharmacogenomics.

About Medco

Medco Health Solutions, Inc. (NYSE: MHS) is the nation's leading pharmacybenefit manager based on its 2007 total net revenues of more than $44 billion.Medco's prescription drug benefit programs, covering approximately one-in-fiveAmericans, are designed to drive down the cost of pharmacy health care forprivate and public employers, health plans, labor unions and governmentagencies of all sizes, for individuals served by the Medicare Part DPrescription Drug Program, and those served by Medco's specialty pharmacysegment, Accredo Health Group. Medco, the world's most advanced pharmacy(R),is positioned to serve the unique needs of patients with chronic and complexconditions through its Medco Therapeutic Resource Centers(R), including itsenhanced diabetes pharmacy care practice through the Liberty acquisition.Medco is the highest-ranked independent pharmacy benefit manager on the 2008Fortune 100 list. On the Net: http://www.medcohealth.com.

This press release contains "forward-looking statements" as that term isdefined in the Private Securities Litigation Reform Act of 1995. Thesestatements involve risks and uncertainties that may cause results to differmaterially from those set forth in the statements. No forward-lookingstatement can be guaranteed, and actual results may differ materially fromthose projected. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, orotherwise. Forward-looking statements in this press release should beevaluated together with the risks and uncertainties that affect our business,particularly those mentioned in the Risk Factors section of the Company'sAnnual Report on Form 10-K and Quarterly Reports on Form 10-Q filed with theSecurities and Exchange Commission.

SOURCE Medco Health Solutions, Inc.