Insmed Provides Update on IPLEX(TM) Launch; Company Shares Details on Payer Usage Program and Pricing

On May 23, 2006, Insmed announced the IPLEX Utilization Program toapproximately 800 national payers as part of its comprehensive launchcommunications. In a letter to payers, Insmed informed them of theavailability and pricing of IPLEX. Prominent in the announcement was astatement specifically detailing Insmed's pricing commitment to thismarket.

Insmed proactively created the utilization program, and informedthe payer universe that the annual charge for therapy is limited toactual milligrams prescribed and used. The utilization program assuresthat there is no charge for unused product remaining after theprescribed dose is extracted. Any remaining product discarded as wasteis accounted for, and replaced by the company at no charge to thepayer or patient, to assure that the payer or patient pays only forthe amount dosed and administered. The utilization program, and otherdistribution activities, is managed by Insmed's single point ofcontact system, PlexPoint(TM).

"Insmed is committed to the Primary IGFD market place. Everythingwe've done during launch was designed to increase patient access tothis important once-a-day therapy," remarked Philip J. Young, ChiefBusiness Officer. "We made the decision to bring IPLEX to the marketas rapidly as possible after receiving FDA approval and OrphanDesignation in December 2005. As part of our launch we proactivelyannounced the IPLEX Utilization Program, the first of its kind in theindustry, guaranteeing payers and patients they would only pay forIPLEX that is prescribed and used."

Insmed is aware that price comparisons between the available IGF-Ireplacement therapies have been attempted. However, the companybelieves that it would be inappropriate to draw conclusions fromunbalanced pricing comparisons as the assumptions are not based infact, nor reinforced by market practices and physician prescribingtrends. The therapeutic dose range for IPLEX is 1 mg/kg to 2 mg/kgtaken once daily. A comparison using only the 2 mg/kg dose isinappropriate in light of the fact that the patients with the bestgrowth response in the pivotal study, (efficacy which was similar topublished studies with rhIGF-I), received approximately 1.4 mg/kg,once daily.

"We believe we have a competitively priced product with anexcellent safety and efficacy profile. We are pleased with how wellthe market is responding to IPLEX at this early stage and believe thatthe attributes of IPLEX will continue to prove attractive toprescribing physicians, payers and patients," Young added.

Insmed is committed to this utilization program until the releaseof a shelf stable, multi-dose vial and delivery system, which isplanned to be available in 2007. We believe our manufacturing facilityin Boulder, Colorado provides us with the capability to manage thecost of IPLEX within a reasonable range while we continue thedevelopment of a new product formulation.

The Insmed Sales and Managed Care teams are working to ensure thatthe target audiences are aware of the Utilization Program and theattributes of IPLEX therapy. Pricing for IPLEX, the only FDA approvedonce-daily IGF-I replacement therapy, is available on all of thestandard pharmaceutical databases. Further information about IPLEX isavailable at www.go-IPLEX.com or by calling 1-866-go-IPLEX(1-866-464-7539).

About Insmed Incorporated

Insmed is a biopharmaceutical company focused on the developmentand commercialization of drug candidates for the treatment ofmetabolic diseases and endocrine disorders with unmet medical needs.For more information, please visit www.insmed.com. The Company'sleading product, IPLEX was approved as an orphan drug by the UnitedStates Food and Drug Administration in December 2005 for the treatmentof growth failure in children with severe primary IGF-I deficiency(Primary IGFD) or with growth hormone (GH) gene deletion who havedeveloped neutralizing antibodies to GH.

About IPLEX

IPLEX, a complex of recombinant human IGF-I and its bindingprotein IGFBP-3 (rhIGF-I/rhIGFBP-3), is the only once-daily IGF-Ireplacement therapy. It is also the only FDA-approved therapy thatprovides both IGF-I and IGFBP-3 to treat children with severe primaryIGFD. The drug which was launched in the second quarter of 2006, isalso being investigated for various other indications with unmetmedical needs, including extreme insulin resistance, myotonic musculardystrophy and HIV Associated Adipose Redistribution Syndrome (HARS).

About the Condition

Severe primary IGFD is a genetic or acquired condition in whichpatients do not generate sufficient quantities of insulin-like growthfactor-I (IGF-I) due to a defect in the growth hormone (GH)receptor/IGF-I pathway. Gene mutations leading to growth failure dueto IGF-I deficiency have been identified in the growth hormonereceptor, in the GH receptor signalling pathway, and in the IGF-I geneitself. Patients with severe primary IGFD present with marked shortstature and a poor prognosis for adult stature.

Statements included within this press release, which are nothistorical in nature, may constitute forward-looking statements forpurposes of the safe harbor provided by the Private SecuritiesLitigation Reform Act of 1995. Forward-looking statements in thispress release include, but are not limited to, statements regardingour IPLEX utilization program, regulatory and business strategies,manufacturing capabilities, product costs, plans and objectives ofmanagement and growth opportunities for existing or proposed products.Such forward-looking statements are subject to numerous risks anduncertainties, including risks that product candidates may fail in theclinic or may not be successfully launched, marketed, manufactured orreimbursed, we may lack financial resources to complete development ofproduct candidates, the FDA may interpret the results of our studiesdifferently than we have, competing products may be more successful,demand for new pharmaceutical products may decrease, thebiopharmaceutical industry may experience negative market trends andother risks detailed from time to time in our filings with theSecurities and Exchange Commission. As a result of these and otherrisks and uncertainties, actual results may differ materially fromthose described in this press release. For further information withrespect to factors that could cause actual results to differ fromexpectations, reference is made to our reports filed by the Companywith the Securities and Exchange Commission under the SecuritiesExchange Act of 1934, as amended. The forward-looking statements madein this release are made only as of the date hereof and Insmeddisclaims any intention or responsibility for updating predictions orfinancial guidance contained in this release.