Synthetic Biologics Reports Second Quarter 2012 Financial Results -- Addition of Monoclonal Antibodies for Infectious Diseases Emphasizes Focus on Synthetic Biologics -- For Immediate Release Ann Arbor, MI

Synthetic Biologics Reports Second Quarter

2012 Financial Results

-- Addition of Monoclonal Antibodies

for Infectious Diseases Emphasizes Focus on Synthetic Biologics --

Ann Arbor, MI, August 14, 2012 -

Synthetic Biologics, Inc. (NYSE MKT: SYN), a developer of synthetic biologics and innovative medicines for unmet medical needs,

today reported financial results for the three and six months ended June 30, 2012 and summarized operational highlights.

Operational Highlights

Expanding Synthetic Biologic Programs

Advancing Clinical Trial Programs

Board of Directors - Improved

Corporate Governance

"We continue to broaden our reach

within the synthetic biologics area as evidenced by the recent expansion of our relationship with Intrexon for the development

of monoclonal antibodies to treat infectious diseases. These discovery programs enhance our product pipeline and further emphasize

our commitment to the development of new treatment options for unmet medical needs," said Jeffrey Riley, Chief Executive

Officer of Synthetic Biologics. "We look forward to announcing more about our infectious disease targets and program progress

in the near future."

Three and Six Months Ended June 30, 2012 Financial Results

As part of management's plan to streamline

our focus, we sold the clinical reference lab on March 8, 2012. Laboratory revenues for the three and six months ended June 30,

2012 and June 30, 2011 were charged to discontinued operations, resulting in no revenues for these periods. In addition, the gain

on the sale of the clinical reference lab of $677,000 was included in discontinued operations for the six months ended June 30,

General and administrative expenses were

$1.2 million and $2.6 million for the three and six months ended June 30, 2012, respectively, compared to $524,000 and $1.8 million

for the same periods in 2011. These increases of 124% and 50%, respectively, are primarily the result of additional employee costs,

the expansion of our investor relation activities and legal fees related to various Securities and Exchange Commission filings.

Charges related to stock-based compensation were $287,000 and $786,000 for the three and six months ended June 30, 2012, respectively,

compared to $51,000 and $810,000 for the same periods in 2011.

Research and development expenses were

$547,000 and $933,000 for the three and six months ended June 30, 2012, respectively, compared to $281,000 and $512,000 for the

same periods in 2011. These increases of 95% and 82%, respectively, are primarily the result of additional employee costs and increased

program costs associated with our expanded pipeline, including the initiation of our preclinical program for the treatment of PAH

and our clinical trial for the treatment of cognitive dysfunction in MS.

Other income was $7,000 for the three months

ended June 30, 2012, compared to other expense of $761,000 for the same period in 2011. Other income was $12,000 for the six months

ended June 30, 2012, compared to other expense of $1.5 million for the same period in 2011. Other expense for the three and six

months ended June 30, 2011 included $760,000 and $1.6 million, respectively, relating to the estimated fair value of the warrants

associated with the January 2011 and April 2011 financings, adjusted for the change in their fair value at the end of each period.

Cash at June 30, 2012 was $5.9 million

compared to $6.7 million at December 31, 2011. As of July 31, 2012, we had approximately $5.6 million in cash.

About Synthetic Biologics, Inc.

Synthetic Biologics is a biotechnology

company focused on the development of product candidates to address serious diseases and unmet medical needs. Synthetic Biologics

is developing the following synthetic biologic candidates: a series of monoclonal antibodies (mAbs) for the treatment of serious

infectious diseases not adequately addressed by existing therapies and a synthetic DNA-based therapy for the treatment of pulmonary

arterial hypertension (PAH). The Company is also developing drug candidates for the treatment of relapsing-remitting multiple sclerosis

(MS), cognitive dysfunction in MS, amyotrophic lateral sclerosis (ALS) and fibromyalgia (partnered with Meda AB). For more information,

please visit Synthetic Biologics' website at www.syntheticbiologics.com.

UltraVector and RheoSwitch Therapeutic

System are registered trademarks of Intrexon Corporation.

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 our continued focus of our

efforts in the field of synthetic biology and advancing our clinical programs and the expected size of the future market for sales

of oral disease-modifying therapies for MS. 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 our therapeutics, a failure of our

clinical trials to be commenced or completed on time or to achieve desired results, a failure of our clinical trials to receive

anticipated funding, a failure of gene therapy to receive market acceptance, a failure of our monoclonal antibodies for the treatment

of infectious diseases to be successfully developed or commercialized, our inability to maintain our licensing agreements, including

our agreement with Intrexon, or a failure by us or our strategic partners to successfully commercialize products and other factors

described in Synthetic Biologics' report on Form 10-K/A for the year ended December 31, 2011 and any other 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.

- Financial Tables to Follow -

For further information, please contact:

Vice President of Corporate Communication

(734) 332-7800, Ext. 22