Myogen Initiates Phase 3 Clinical Trial of Darusentan in Patients with Resistant Hypertension.

DENVER -- Myogen, Inc. (Nasdaq: MYOG), a biopharmaceutical company focused on the discovery, development and commercialization of small molecule therapeutics for the treatment of cardiovascular disorders, today announced the initiation of DORADO (DAR-311), an international Phase 3 clinical trial to evaluate darusentan in patients with resistant hypertension (RHTN). Myogen currently plans to initiate a second international Phase 3 clinical trial, DAR-312, for the same indication in the fourth quarter of this year. Contemporary clinical guidelines define RHTN as "the failure to achieve goal blood pressure in patients who are adhering to full doses of an appropriate three-drug regimen that includes a diuretic."

The primary objective of DORADO, a Phase 3 randomized, double-blind, placebo-controlled parallel group trial, is to determine if darusentan is effective in reducing systolic blood pressure in resistant hypertension patients currently treated with full doses of four or more antihypertensive medications, one of which is a diuretic. Patients are eligible for enrollment in this trial if they have a systolic blood pressure greater than or equal to 140 mmHg and no other compelling conditions. For patients with diabetes and/or chronic kidney disease, the blood pressure inclusion criterion is a systolic blood pressure greater than 130 mmHg. Approximately 352 patients will be randomized to one of three doses of darusentan (50, 100, or 300 mg qd) versus placebo in a ratio of 7:7:7:11. The treatment period for the trial is 14 weeks. The primary endpoint of the trial is change from baseline to week 14 in trough sitting systolic blood pressure as compared to placebo. Upon completion of the 14-week assessment period, patients will be eligible to enroll in a long-term safety study. Patients will be treated and followed for safety for at least six months with a mean exposure expected to be in excess of one year.

About Darusentan

Darusentan is a non-sulfonamide, propanoic-acid class, type-A selective endothelin receptor antagonist (ERA) being investigated in clinical trials as an add-on oral therapy for patients with resistant hypertension. Contemporary clinical guidelines define RHTN as "the failure to achieve goal blood pressure in patients who are adhering to full doses of an appropriate three-drug regimen that includes a diuretic."

In August 2005, Myogen announced top line results of DAR-201, a Phase 2b randomized, double-blind, placebo-controlled clinical trial. The trial evaluated the effect of darusentan on systolic blood pressure in 115 patients with RHTN. Results of the trial demonstrated that 150 mg (at week 8) and 300 mg (at week 10) of darusentan dosed once daily provided statistically significant placebo-corrected reductions in systolic blood pressure measured by standard sphygmomanometry, as well as 24-hour ambulatory blood pressure monitoring (ABPM). Clinically meaningful reductions in systolic and diastolic blood pressure were also observed at earlier time points at lower doses. Trial results also demonstrated darusentan was generally well tolerated. Additional results from the Phase 2b study were presented at ACC.06, the 55th Annual Scientific Session of the American College of Cardiology held in March 2006, and at the American Society of Hypertension Annual Meeting held in May 2006.

About Myogen

Myogen has two product candidates in late-stage clinical development: ambrisentan for the treatment of patients with pulmonary arterial hypertension (PAH) and darusentan for the treatment of patients with resistant hypertension. Myogen and GlaxoSmithKline have entered into a global PAH collaboration in which Myogen has marketing and distribution rights to GlaxoSmithKline's Flolan(R) (epoprostenol sodium) for Injection in the United States and GlaxoSmithKline has licensed ambrisentan from Myogen for all territories outside of the United States, where Myogen retains exclusive rights. Myogen also conducts a target and drug discovery research program focused on the development of disease-modifying drugs for the treatment of chronic heart failure and related cardiovascular disorders. Please visit Myogen's website at www.myogen.com.

Safe Harbor Statement

This press release contains forward-looking statements that involve significant risks and uncertainties, including the statements relating to the potential of darusentan as a treatment for resistant hypertension. Actual results could differ materially from those projected and Myogen cautions investors not to place undue reliance on the forward-looking statements contained in this release.

The results of Myogen's prior clinical trials of its product candidates, including darusentan, do not necessarily predict the results of future clinical trials. Preliminary results may not be confirmed upon full analysis of the detailed results of a trial. There can be no assurance that Myogen's product candidates, including darusentan, have better safety profiles than competing products. Among other things, Myogen's results may be affected by competition from other pharmaceutical and biotechnology companies, Myogen's ability to successfully develop and market its current products, difficulties or delays in its clinical trials, regulatory developments involving current and future products and its effectiveness at managing its financial resources. If the Company's product candidates, including darusentan, do not meet the safety or efficacy endpoints in clinical evaluations, they will not receive regulatory approval and the Company will not be able to market them. Even if Myogen's product candidates meet safety and efficacy endpoints, regulatory authorities may not approve them, or the Company may face post-approval problems that require the withdrawal of its products from the market. If the Company is unable to raise additional capital when required or on acceptable terms, it may have to significantly delay, scale back or discontinue one or more of its drug development or discovery research programs. Myogen may not ever have any products that generate significant revenue.

Additional risks and uncertainties relating to the company and its business can be found in the "Risk Factors" section of Myogen's Form 10-K for the year ended December 31, 2005 and Myogen's periodic reports on Form 10-Q and Form 8-K. Myogen is providing the information contained in this release as of the date of the release and does not undertake any obligation to update any forward-looking statements as a result of new information, future events or otherwise.