Ironwood Pharmaceuticals Reports First Quarter 2023 Results; Maintains Full Year 2023 Financial Guidance - LINZESS (Iinaclotide) EUTRx prescription demand growth increased 10% year- over-year; LINZE

Ironwood Pharmaceuticals

Reports First Quarter 2023 Results; Maintains Full Year 2023

LINZESS (Iinaclotide) EUTRx prescription demand growth increased 10% year-

over-year; LINZESS U.S. net sales of $250 million, an increase of 8%

GAAP net income of $46 million and adjusted EBITDA of $60 million;

ended Q1 2023 with $740 million in cash and cash equivalents -

Mass., May 4, 2023 - Ironwood Pharmaceuticals, Inc. (Nasdaq: IRWD), a GI-focused

healthcare company, today reported its first quarter 2023 results and recent business performance.

"We are off to a terrific start

to the year, as the strong momentum of LINZESS continues," said Tom McCourt, chief executive officer of Ironwood. "In the

first quarter, LINZESS prescription demand increased over 10% year-over-year, with LINZESS achieving an all-time high in new-to-brand

patient volume. We look forward to our upcoming June 14th PDUFA date for a potential pediatric functional constipation indication in

children and adolescents ages 6 to 17, which, if approved, would further expand the growth potential of the brand. In addition, we made

progress with our pipeline programs, CNP-104 and IW-3300, and finished the quarter with $740 million of cash and cash equivalents on

our balance sheet. We believe we are well-positioned to maximize LINZESS growth and continue to build an innovative GI portfolio supporting

the next growth horizon for the company."

First Quarter 2023 Financial Highlights1

(in thousands, except for per share

First Quarter 2023 Corporate Highlights

First Quarter 2023 Financial Results

1 Adjusted EBITDA is calculated

by subtracting mark-to-market adjustments on derivatives related to Ironwood's 2022 Convertible Notes, restructuring expenses,

net interest expense, income taxes, depreciation and amortization from GAAP net income. For purposes of this guidance, Ironwood has assumed

that it will not incur material expenses related to business development activities in 2023.

Non-GAAP Financial Measures

Ironwood presents non-GAAP net income

and non-GAAP net income per share to exclude the impact of net gains and losses on derivatives related to Ironwood's 2022 Convertible

Notes that are required to be marked-to-market. Non-GAAP adjustments are further detailed below:

Ironwood also presents adjusted EBITDA,

a non-GAAP measure, as well as guidance on adjusted EBITDA. Adjusted EBITDA is calculated by subtracting mark-to-market adjustments on

derivatives related to Ironwood's 2022 Convertible Notes, net interest expense, income taxes, depreciation and amortization from

GAAP net income. The adjustments are made on a similar basis as described above related to non-GAAP net income, as applicable.

Management believes this non-GAAP information

is useful for investors, taken in conjunction with Ironwood's GAAP financial statements, because it provides greater transparency

and period-over-period comparability with respect to Ironwood's operating performance. These measures are also used by management

to assess the performance of the business. Investors should consider these non-GAAP measures only as a supplement to, not as a substitute

for or as superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non-GAAP financial measures

are unlikely to be comparable with non-GAAP information provided by other companies. For a reconciliation of non-GAAP net income and

non-GAAP net income per share to GAAP net income and GAAP net income per share, respectively, and for a reconciliation of adjusted EBITDA

to GAAP net income, please refer to the tables at the end of this press release.

Ironwood does not provide guidance on

GAAP net income or a reconciliation of expected adjusted EBITDA to expected GAAP net income because, without unreasonable efforts, it

is unable to predict with reasonable certainty the non-GAAP adjustments used to calculate adjusted EBITDA. These adjustments are

uncertain, depend on various factors and could have a material impact on GAAP net income for the guidance period.

Conference Call Information

Ironwood will host a conference call

and webcast at 8:30 a.m. Eastern Time on Thursday, May, 4 2023 to discuss its first quarter 2023 results and recent business activities.

Individuals interested in participating in the call should dial (888) 330-2384 (U.S. and Canada) or (240) 789-2701 (international) using

conference ID number and event passcode 4671230. To access the webcast, please visit the Investors section of Ironwood's website

at www.ironwoodpharma.com at least 15 minutes prior to the start of the call to ensure adequate time for any software downloads that

may be required. The call will be available for replay via telephone starting at approximately 11:30 a.m. Eastern Time on May 4, 2023,

running through 11:59 p.m. Eastern Time on May 18, 2023. To listen to the replay, dial (800) 770-2030 (U.S. and Canada) or (647) 362-9199

(international) using conference ID number 4671230. The archived webcast will be available on Ironwood's website for 14 days beginning

approximately one hour after the call has completed.

About Ironwood Pharmaceuticals

Ironwood Pharmaceuticals (Nasdaq: IRWD),

an S&P SmallCap 600 company, is a leading gastrointestinal (GI) healthcare company on a mission to advance the treatment of

GI diseases and redefine the standard of care for GI patients. We are pioneers in the development of LINZESS (linaclotide), the

U.S. branded prescription market leader for adults with irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation

(CIC). Under the guidance of our seasoned industry leaders, we continue to build upon our history of GI innovation and challenge what

has been done before to shape what the future holds. We keep patients at the heart of our R&D and commercialization efforts to reduce

the burden of GI diseases and address significant unmet needs.

Founded in 1998, Ironwood Pharmaceuticals

is headquartered in Boston, Massachusetts.

We routinely post information that may

be important to investors on our website at www.ironwoodpharma.com.

About LINZESS (linaclotide)

is the #1 prescribed brand in the U.S. for the treatment of adult patients with irritable bowel syndrome with constipation ("IBS-C")

or chronic idiopathic constipation ("CIC"), based on IQVIA data.

a once-daily capsule that helps relieve the abdominal pain, constipation, and overall abdominal symptoms of bloating, discomfort and

pain associated with IBS-C, as well as the constipation, infrequent stools, hard stools, straining, and incomplete evacuation associated

with CIC. The recommended dose is 290 mcg for IBS-C patients and 145 mcg for CIC patients, with a 72-mcg dose approved for use in CIC

depending on individual patient presentation or tolerability. LINZESS should be taken at least 30 minutes before the first meal of the

contraindicated in pediatric patients less than 2 years of age. In neonatal mice, linaclotide increased fluid secretion as a consequence

of age-dependent elevated GC-C agonism resulting in mortality within the first 24 hours due to dehydration. There was no age-dependent

trend in GC-C intestinal expression in a clinical study of children 2 to less than 18 years of age; however, there are insufficient data

available on GC-C intestinal expression in children less than 2 years of age to assess the risk of developing diarrhea and its potentially

serious consequences in these patients. The safety and effectiveness of LINZESS in patients less than 18 years of age have not been established.

LINZESS is not a laxative; it is the

first medicine approved by the FDA in a class called GC-C agonists. LINZESS contains a peptide called linaclotide that activates the

GC-C receptor in the intestine. Activation of GC-C is thought to result in increased intestinal fluid secretion and accelerated transit

and a decrease in the activity of pain-sensing nerves in the intestine. The clinical relevance of the effect on pain fibers, which is

based on nonclinical studies, has not been established.

In the United States, Ironwood and AbbVie

co-develop and co-commercialize LINZESS for the treatment of adults with IBS-C or CIC. In Europe, AbbVie markets linaclotide under the

brand name CONSTELLA for the treatment of adults with moderate to severe IBS-C. In Japan, Ironwood's partner, Astellas, markets

linaclotide under the brand name LINZESS for the treatment of adults with IBS-C or CIC. Ironwood also has partnered with AstraZeneca

for development and commercialization of LINZESS in China, and with AbbVie for development and commercialization of linaclotide in all

other territories worldwide.

LINZESS Important Safety Information

INDICATIONS AND USAGE

LINZESS (linaclotide) is indicated in

adults for the treatment of both irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC).

IMPORTANT SAFETY INFORMATION

Warnings and Precautions