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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>UNITED STATES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SECURITIES AND EXCHANGE COMMISSION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WASHINGTON, D.C. 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>FORM 8-K</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>CURRENT REPORT</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Date of Report (date of earliest event reported):
<B>October 16, 2012</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 18pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Synthetic Biologics, Inc.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Exact name of registrant as specified in
charter)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Nevada</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(State or other jurisdiction of incorporation)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 50%; font-size: 10pt; font-weight: bold; text-align: center">01-12584</TD>
    <TD STYLE="width: 50%; font-size: 10pt; font-weight: bold; text-align: center">13-3808303</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; text-align: center">(Commission File Number)</TD>
    <TD STYLE="font-size: 10pt; text-align: center">(IRS Employer Identification No.)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>617 Detroit Street, Suite 100</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Ann Arbor, MI 48104</B></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Address of principal executive offices
and zip code)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(734) 332-7800</B></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Registrant&rsquo;s telephone number including
area code)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>N/A</B></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Former Name and Former Address)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">Check the appropriate box below if the Form
8-K filing is intended to simultaneously satisfy the filing obligation of registrant under any of the following provisions:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

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    <TD STYLE="width: 48px">&nbsp;</TD>
    <TD STYLE="width: 48px; font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#168;</FONT></TD>
    <TD STYLE="font-size: 10pt">Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)</TD></TR>
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    <TD STYLE="width: 48px">&nbsp;</TD>
    <TD STYLE="width: 48px; font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#168;</FONT></TD>
    <TD STYLE="font-size: 10pt">Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act (17 CFR 240.14a-12)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 48px">&nbsp;</TD>
    <TD STYLE="width: 48px; font-size: 10pt"><FONT STYLE="font-family: Wingdings">&#168;</FONT></TD>
    <TD STYLE="font-size: 10pt">Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))</TD></TR>
</TABLE>
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    <TD STYLE="width: 48px">&nbsp;</TD>
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    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Pre-commencement communications pursuant to Rule 13e-4(c)
under the Exchange Act (17 CFR 240.13e-4(c))&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P></TD></TR>
</TABLE>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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    <TD STYLE="width: 9%; font-size: 10pt; font-weight: bold">Item 3.02</TD>
    <TD STYLE="width: 91%; font-size: 10pt; font-weight: bold">Unregistered Sales of Equity Securities.</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">On October 16, 2012 a closing was held for the transaction previously
announced on August 8, 2012 between Synthetic Biologics, Inc. (the &ldquo;Company&rdquo;) and Intrexon Corporation (&ldquo;Intrexon&rdquo;).
The Company issued 3,552,210 shares of Company common stock (the &ldquo;Shares&rdquo;) at a purchase price equal to the $0.001
par value of such shares, which issuance is also deemed paid in partial consideration for the execution and delivery of the Exclusive
Channel Collaboration Agreement, dated August 6, 2012, between the Company and Intrexon. The offer and issuance of the Shares have
not been registered under the Securities Act of 1933, as amended (the &ldquo;Securities Act&rdquo;), and therefore may not be offered
or sold in the United States absent registration or an applicable exemption from registration requirements. For this issuance,
the Company is relying on the exemption from federal registration under Section 4(2) of the Securities Act, based on the Company&rsquo;s
belief that the offer and sale of the Shares does not involve a public offering as Intrexon is an &ldquo;accredited investor&rdquo;
as defined under Section 501 promulgated under the Securities Act and no general solicitation has been involved in the offering.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 180px; font-size: 10pt; font-weight: bold">Item 8.01 Other Events.</TD>
    <TD>&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">On October 16, 2012, the Company completed the closing of its
Exclusive Channel Collaboration transaction with Intrexon, which was previously announced in the Company&rsquo;s press release
on August 8, 2012. The Company intends to use specified patents and other intellectual property of Intrexon in connection with
the research, development, use, importing, manufacture, sale, and offer for sale of monoclonal antibody therapies for the treatment
of eight specific target infectious disease indications (the &ldquo;Field&rdquo;). Initially, the Company&rsquo;s development efforts
will target three infectious diseases within the Field. Pursuant to the terms of the Stock Purchase Agreement between the Company
and Intrexon dated August 6, 2012, the Company met all of the requisite closing conditions, including the receipt of NYSE MKT approval,
and has issued the Shares to Intrexon, which issuance is deemed paid in partial consideration for the execution and delivery of
the Exclusive Channel Collaboration Agreement, dated August 6, 2012, between the Company and Intrexon. Stockholder approval of
such issuance was obtained at the Company&rsquo;s Annual Meeting of Stockholders held on October 5, 2012.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">In connection with the transactions contemplated by the Stock
Issuance Agreement, and pursuant to the First Amendment to Registration Rights Agreement, the Company agreed to file a &ldquo;resale&rdquo;
registration statement (the &ldquo;Registration Statement&rdquo;) registering the resale of the shares issued and to be issued
under the Stock Issuance Agreement. None of the shares to be issued under the Stock Issuance Agreement need to be registered until<FONT STYLE="color: #1F497D">
</FONT>April 30, 2013. Under that agreement, the Company will be obligated to use its reasonable best efforts to cause the &ldquo;resale&rdquo;
registration statement to be declared effective as promptly as practicable after filing and to maintain the effectiveness of the
registration statement until all securities therein are sold or are otherwise can be sold pursuant to Rule 144, without any restrictions.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Pursuant to the requirements of the Securities Exchange Act
of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt">Dated: October 17, 2012</TD>
    <TD COLSPAN="2">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">SYNTHETIC BIOLOGICS, INC.</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">(Registrant)</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 58%">&nbsp;</TD>
    <TD STYLE="width: 5%">&nbsp;</TD>
    <TD STYLE="width: 37%">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-bottom: 1.5pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt">By:</TD>
    <TD STYLE="border-bottom: black 1.5pt solid; font-size: 10pt">/s/ Jeffrey Riley</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">Name: Jeffrey Riley</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt">Title: &nbsp;&nbsp;President and Chief Executive Officer</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>



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{"company-data": {"conformed-name": "Synthetic Biologics, Inc.", "cik": "0000894158", "assigned-sic": "2834", "irs-number": "133808303", "state-of-incorporation": "NV", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-12584", "film-number": "121147250"}, "business-address": {"street1": "3985 RESEARCH PARK DRIVE,", "street2": "SUITE 200", "city": "ANN ARBOR", "state": "MI", "zip": "48108", "phone": "(734) 332-7800"}, "mail-address": {"street1": "3985 RESEARCH PARK DRIVE,", "street2": "SUITE 200", "city": "ANN ARBOR", "state": "MI", "zip": "48108"}, "former-company": [{"former-conformed-name": "ADEONA PHARMACEUTICALS, INC.", "date-changed": "20081027"}, {"former-conformed-name": "PIPEX PHARMACEUTICALS, INC.", "date-changed": "20061214"}, {"former-conformed-name": "SHEFFIELD PHARMACEUTICALS INC", "date-changed": "19970730"}]}
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM 8-K
CURRENT REPORT
Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934
Date of Report (date of earliest event reported):
October 16, 2012
Synthetic Biologics, Inc.
(Exact name of registrant as specified in
charter)
Nevada
(State or other jurisdiction of incorporation)
01-12584
13-3808303
(Commission File Number)
(IRS Employer Identification No.)
617 Detroit Street, Suite 100
Ann Arbor, MI 48104
(Address of principal executive offices
and zip code)
(734) 332-7800
(Registrant's telephone number including
area code)
N/A
(Former Name and Former Address)
Check the appropriate box below if the Form
8-K filing is intended to simultaneously satisfy the filing obligation of registrant under any of the following provisions:
¨
Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
¨
Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act (17 CFR 240.14a-12)
¨
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
¨
Pre-commencement communications pursuant to Rule 13e-4(c)
under the Exchange Act (17 CFR 240.13e-4(c))
Item 3.02
Unregistered Sales of Equity Securities.
On October 16, 2012 a closing was held for the transaction previously
announced on August 8, 2012 between Synthetic Biologics, Inc. (the "Company") and Intrexon Corporation ("Intrexon").
The Company issued 3,552,210 shares of Company common stock (the "Shares") at a purchase price equal to the $0.001
par value of such shares, which issuance is also deemed paid in partial consideration for the execution and delivery of the Exclusive
Channel Collaboration Agreement, dated August 6, 2012, between the Company and Intrexon. The offer and issuance of the Shares have
not been registered under the Securities Act of 1933, as amended (the "Securities Act"), and therefore may not be offered
or sold in the United States absent registration or an applicable exemption from registration requirements. For this issuance,
the Company is relying on the exemption from federal registration under Section 4(2) of the Securities Act, based on the Company's
belief that the offer and sale of the Shares does not involve a public offering as Intrexon is an "accredited investor"
as defined under Section 501 promulgated under the Securities Act and no general solicitation has been involved in the offering.
Item 8.01 Other Events.
On October 16, 2012, the Company completed the closing of its
Exclusive Channel Collaboration transaction with Intrexon, which was previously announced in the Company's press release
on August 8, 2012. The Company intends to use specified patents and other intellectual property of Intrexon in connection with
the research, development, use, importing, manufacture, sale, and offer for sale of monoclonal antibody therapies for the treatment
of eight specific target infectious disease indications (the "Field"). Initially, the Company's development efforts
will target three infectious diseases within the Field. Pursuant to the terms of the Stock Purchase Agreement between the Company
and Intrexon dated August 6, 2012, the Company met all of the requisite closing conditions, including the receipt of NYSE MKT approval,
and has issued the Shares to Intrexon, which issuance is deemed paid in partial consideration for the execution and delivery of
the Exclusive Channel Collaboration Agreement, dated August 6, 2012, between the Company and Intrexon. Stockholder approval of
such issuance was obtained at the Company's Annual Meeting of Stockholders held on October 5, 2012.
In connection with the transactions contemplated by the Stock
Issuance Agreement, and pursuant to the First Amendment to Registration Rights Agreement, the Company agreed to file a "resale"
registration statement (the "Registration Statement") registering the resale of the shares issued and to be issued
under the Stock Issuance Agreement. None of the shares to be issued under the Stock Issuance Agreement need to be registered until
April 30, 2013. Under that agreement, the Company will be obligated to use its reasonable best efforts to cause the "resale"
registration statement to be declared effective as promptly as practicable after filing and to maintain the effectiveness of the
registration statement until all securities therein are sold or are otherwise can be sold pursuant to Rule 144, without any restrictions.
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act
of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
Dated: October 17, 2012
SYNTHETIC BIOLOGICS, INC.
(Registrant)
By:
/s/ Jeffrey Riley
Name: Jeffrey Riley
Title:   President and Chief Executive Officer