Synthetic Biologics Reports Year End 2014 Financial Results and Operational Highlights -- Steady Progress in All Programs; Two Phase 2 Clinical Trials to Start in 2015 -- -- Conference Call Today

Synthetic Biologics Reports Year End

2014 Financial Results and Operational Highlights

-- Steady Progress in All Programs;

Two Phase 2 Clinical Trials to Start in 2015 --

-- Conference Call Today, March 16,

2015, at 8:30 a.m. (ET) --

MD, March 16, 2015 - Synthetic Biologics, Inc.

(NYSE MKT: SYN), a developer of pathogen-specific therapies for serious infections and diseases, with a focus on protecting

the microbiome, today reported financial results for the year ended December 31, 2014, and provided

an operational update.

"During the past year Synthetic

Biologics made important advances in furthering our goal of building a late-stage, pathogen-specific, microbiome-focused portfolio

with strong opinion leader support and a solid investor base," said Jeffrey Riley, Chief Executive Officer of Synthetic

Biologics. "This year we plan to initiate Phase 2 clinical trials in two programs - SYN-004, a preventive therapeutic

for C. difficile infection, and SYN-010, a treatment for irritable bowel syndrome with constipation (IBS-C), with topline

data expected from both programs by year end. In addition, we are making good progress with previously reported partnering discussions

on our relapsing-remitting multiple sclerosis (RRMS) program."

Clinical Programs Update

SYN-004 is a first-in-class oral

enzyme preventive therapy designed to protect the gut microbiome from the unintended harmful effects of intravenous (IV) antibiotics,

for the prevention of C. difficile infection.

SYN-010 is a proprietary, modified-release

statin formulation optimal for reducing methane-production by certain microorganisms in the gut to treat the underlying cause of

pain, bloating, and constipation associated with IBS-C.

SYN-005 is a novel combination of

two monoclonal antibodies designed to treat Pertussis (whooping cough) by targeting and neutralizing pertussis toxin.

TrimestaTM (oral estriol)

may offer a differentiated mechanism of action in the treatment of RRMS, as demonstrated in clinical trials. Based on Phase

2 clinical findings, Trimesta may offer both anti-inflammatory (decrease in relapse rate) and neuroprotective (improvements in

disability and cognition) benefits for patients with MS when taken in combination with Copaxone .

Year Ended December 31, 2014 Financial

General and administrative expenses were

$6.0 million for the year ended December 31, 2014, compared to $5.8 million for the same period in 2013. This increase is primarily

the result of supplemental compensation granted by the Board of Directors to executive officers and increased stock-based compensation

expense during the year ended December 31, 2014, which was offset by the decrease of bad debt expense of $763,000 associated with

the note and interest receivables from the sale of Adeona Clinical Laboratory that were determined uncollectible during the year

ended December 31, 2013. Non-cash charges related to stock-based compensation were $1.6 million for the year ended December 31,

2014, compared to $1.3 million for the same period in 2013.

Research and development expenses increased

to $14.5 million for the year ended December 31, 2014, compared to $6.5 million for the same period in 2013. This increase of 123%

is primarily the result of increased program costs associated with expanded clinical development, manufacturing and research activities

within our pathogen-specific, microbiome-focused pipeline, including the Company's C. difficile, IBS-C and Pertussis

programs. Non-cash charges related to stock-based compensation were $803,000 for the year ended December 31, 2014, compared to

$375,000 for the same period in 2013.

Other income was $718,000 for the year

ended December 31, 2014, compared to other income of $21,000 for the same period in 2013. The increase in other income is primarily

due to non-cash income of $620,000 from the change in fair value of warrants for the year ended December 31, 2014. The decrease

in fair value of the warrants was due to the decline in our stock price and the reduction in the time to maturity. There was no

non-cash income or expense relating to fair value warrants for the year ended December 31, 2013.

Cash at December 31, 2014 was $17.5 million

compared to $14.6 million at December 31, 2013.

Synthetic Biologics will hold a conference

call today, Monday, March 16, 2015, at 8:30 a.m. (ET), during which Mr. Riley will provide an operational update and C.

Evan Ballantyne, Synthetic Biologics' Chief Financial Officer, will review the Company's financial results for the year ended December

Interested parties should call 1-888-347-5280

(U.S. toll free), 1-855-669-9657 (Canada toll free), or +1 412-902-4280 (International), fifteen minutes before the start of the

call to register. Registered callers on the toll free line may ask to be placed in the queue for the Question & Answer Session.

The call will also be webcast over the Internet at http://www.videonewswire.com/event.asp?id=101639.

If you are unable to participate during the live conference call, the webcast will be available for replay at the same URL, http://www.videonewswire.com/event.asp?id=101639,

for 30 days after the call.

About Synthetic Biologics, Inc.

Synthetic Biologics, Inc. (NYSE MKT: SYN)

is a clinical-stage biotechnology company developing pathogen-specific therapies for serious infections and diseases, with a focus

on protecting the microbiome. The Company is developing an oral biologic to protect the gut microbiome from intravenous (IV) antibiotics

for the prevention of C. difficile infection, an oral statin treatment to reduce the impact of methane producing organisms

on irritable bowel syndrome with constipation (IBS-C), and in collaboration with Intrexon Corporation (NYSE: XON), a monoclonal

antibody combination for the treatment of Pertussis. In addition, the Company is developing a Phase 2 oral estriol drug for the

treatment of relapsing-remitting multiple sclerosis (MS) and cognitive dysfunction in MS. For more information, please visit Synthetic

Biologics' website at www.syntheticbiologics.com.

This release includes forward-looking

statements on Synthetic Biologics' current expectations and projections about future events. In some cases forward-looking

statements can be identified by terminology such as "may," "should," "potential," "continue,"

"expects," "anticipates," "intends," "plans," "believes," "estimates,"

and similar expressions. These statements are based upon current beliefs, expectations and assumptions and are subject to a number

of risks and uncertainties, many of which are difficult to predict and include statements regarding the planned Phase 2 clinical

trials, expected date of topline data from clinical trials, the expected date of submission of IND application for SYN-010, and

the 505 (b)(2) regulatory pathway anticipated for development of SYN-010. The forward-looking statements are subject to risks and

uncertainties that could cause actual results to differ materially from those set forth or implied by any forward-looking statements.

Important factors that could cause actual results to differ materially from those reflected in Synthetic Biologics' forward-looking

statements include, among others, a failure to receive the necessary regulatory approvals for commercialization of Synthetic Biologics'

therapeutics, a failure of Synthetic Biologics' clinical trials, and those conducted by investigators, to be commenced or

completed on time or to achieve desired results, a failure of Synthetic Biologics' clinical trials to receive anticipated

funding, a failure of Synthetic Biologics' products for the prevention and treatment of diseases to be successfully developed

or commercialized, Synthetic Biologics' inability to maintain its licensing agreements, or a failure by Synthetic Biologics

filings with the SEC. The information in this release is provided only as of the date of this release, and Synthetic Biologics

undertakes no obligation to update any forward-looking statements contained in this release on account of new information, future

events, or otherwise, except as required by law.

For further information, please contact:

Synthetic Biologics: Kris Maly, VP, Corporate

Communication, (734) 332-7800, info@syntheticbiologics.com

Media: Wendy Emanuel, Wellspring Communications,

Inc., (773) 255-9580, wendy@wellspringcom.com

- Financial Tables Follow -

Synthetic Biologics, Inc. and Subsidiaries

(in thousands, except share and per