Exhibit 4.1


 


 





SYNTHETIC
BIOLOGICS, INC.


 


warrant
to purchase common stock


 


NEITHER THE ISSUANCE AND SALE OF THE
SECURITIES REPRESENTED BY THIS CERTIFICATE NOR THE SECURITIES INTO WHICH THESE SECURITIES ARE EXERCISABLE HAVE BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE SECURITIES MAY NOT BE OFFERED FOR SALE,
SOLD, TRANSFERRED OR ASSIGNED (I) IN THE ABSENCE OF (A) AN EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, OR (B) AN OPINION OF COUNSEL SELECTED BY THE HOLDER, IN A FORM REASONABLY SATISFACTORY
TO THE COMPANY, THAT REGISTRATION IS NOT REQUIRED UNDER SAID ACT OR (II) UNLESS SOLD PURSUANT TO RULE 144 OR RULE 144A UNDER SAID
ACT. NOTWITHSTANDING THE FOREGOING, THE SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN OR
FINANCING ARRANGEMENT SECURED BY THE SECURITIES.


 


Warrant No.: __________________


Number of Shares of Common Stock: _____________


Date of Issuance: October __, 2014
("Issuance Date")


 


Synthetic
Biologics, Inc., a Nevada corporation (the "Company"), hereby certifies that, for good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, [_________________________], the registered
holder hereof or its permitted assigns (the "Holder"), is entitled, subject to the terms set forth below, to
purchase from the Company, at the Exercise Price (as defined below) then in effect, upon surrender of this Warrant to
Purchase Common Stock (including any Warrants to Purchase Common Stock issued in exchange, transfer or replacement hereof,
the "Warrant"), at any time or times on or after the date hereof (the “Exercisability
Date”), but not after 11:59 p.m., New York time, on the Expiration Date (as defined below), ______________
(_____________)1 fully paid nonassessable shares of
Common Stock (as defined below) (the "Warrant Shares"). Except as otherwise defined herein,
capitalized terms in this Warrant shall have the meanings set forth in Section 15. This Warrant is the Warrant to purchase
Common Stock issued pursuant to Section 1.1 of that certain Subscription Agreement (the “Purchase
Agreement”), dated as of October __, 2014 (the "Purchase Date"), by and between the Company and
the Holder.


 





 






1    Insert
a number of shares equal to 50% of the number of Shares purchased under the Subscription  Agreement.


 


 




    	 



    	 



    

 


1.    EXERCISE
OF WARRANT.








 


(a)    Mechanics
of Exercise. Subject to the terms and conditions hereof, this Warrant may be exercised by the Holder on any day on or after
the Exercisability Date, in whole or in part, by delivery of a written notice, in the form attached hereto as Exhibit A
(the "Exercise Notice"), of the Holder's election to exercise this Warrant. Within two (2) days following the
Exercise Notice, the Holder shall make payment to the Company of an amount equal to the applicable Exercise Price multiplied by
the number of Warrant Shares as to which this Warrant is being exercised (the "Aggregate Exercise Price") in cash
or by wire transfer of immediately available funds or by notifying the Company that this Warrant is being exercised pursuant to
a Cashless Exercise (as defined in Section 1(d)). The Holder shall not be required to deliver the original Warrant in order to
effect an exercise hereunder, but shall deliver the original Warrant within five (5) Business Days thereafter. Execution and delivery
of the Exercise Notice with respect to less than all of the Warrant Shares shall have the same effect as cancellation of the original
Warrant and issuance of a new Warrant evidencing the right to purchase the remaining number of Warrant Shares. On or before the
first (1st) Business Day following the date on which the Company has received the Exercise Notice, the Company shall
transmit by facsimile an acknowledgment of confirmation of receipt of the Exercise Notice to the Holder and the Company's transfer
agent (the "Transfer Agent"). On or before the third (3rd) Business Day following the date on which
the Company has received the Exercise Notice (the "Share Delivery Date"), the Company shall (X) provided that
(i) such Warrant Shares do not require the placement of any legends restricting the transfer of such Warrant Shares pursuant to
Section 3.8(a) of the Purchase Agreement and (ii) the Transfer Agent is participating in The Depository Trust Company ("DTC")
Fast Automated Securities Transfer Program, upon the request of the Holder, credit such aggregate number of Warrant Shares to which
the Holder is entitled pursuant to such exercise to the Holder's or its designee's balance account with DTC through its Deposit
Withdrawal Agent Commission system, or (Y) if (i) the Transfer Agent is not participating in the DTC Fast Automated Securities
Transfer Program and/or (ii) such Warrant Shares require the placement of legends restricting the transfer of such Warrant Shares
as required by Section 3.8(a) of the Purchase Agreement, issue and dispatch by overnight courier to the address as specified in
the Exercise Notice, a certificate, registered in the Company's share register in the name of the Holder or its designee, for the
number of shares of Common Stock to which the Holder is entitled pursuant to such exercise, which certificate shall, in the case
of subclause (Y)(ii), bear a legend in accordance with Section 3.8(a) of the Purchase Agreement. Upon delivery of the Exercise
Notice, the Holder shall be deemed for all corporate purposes to have become the holder of record of the Warrant Shares with respect
to which this Warrant has been exercised, irrespective of the date such Warrant Shares are credited to the Holder's DTC account
or the date of delivery of the certificates evidencing such Warrant Shares, as the case may be. If this Warrant is submitted in
connection with any exercise pursuant to this Section 1(a) and the number of Warrant Shares represented by this Warrant submitted
for exercise is greater than the number of Warrant Shares being acquired upon an exercise, then the Company shall as soon as practicable
and in no event later than three (3) Business Days after any exercise and at its own expense, issue a new Warrant (in accordance
with Section 7(d)) representing the right to purchase the number of Warrant Shares purchasable immediately prior to such exercise
under this Warrant, less the number of Warrant Shares with respect to which this Warrant is exercised. No fractional shares of
Common Stock are to be issued upon the exercise of this Warrant, but rather the number of shares of Common Stock to be issued shall
be rounded up to the nearest whole number. The Company shall pay any and all transfer taxes which may be payable with respect to
the issuance and delivery of Warrant Shares upon exercise of this Warrant.


 


(b)    Exercise
Price. For purposes of this Warrant, "Exercise Price" means $1.75, subject to adjustment as provided herein.


 




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(c)    Company's
Failure to Timely Deliver Securities. If the Company shall fail for any reason or for no reason to issue to the Holder within
three (3) Trading Days after receipt of the Exercise Notice in compliance with the terms of this Section 1, a certificate for the
number of shares of Common Stock to which the Holder is entitled and register such shares of Common Stock on the Company's share
register or to credit the Holder's balance account with DTC for such number of shares of Common Stock to which the Holder is entitled
upon the Holder's exercise of this Warrant, and if on or after such Trading Day the Holder purchases (in an open market transaction
or otherwise) shares of Common Stock to deliver in satisfaction of a sale by the Holder of shares of Common Stock issuable upon
such exercise that the Holder anticipated receiving from the Company (a "Buy-In"), then, so long as the Holder
has paid the Aggregate Exercise Price, the Company shall, within three (3) Business Days after the Holder's request and in the
Holder's discretion, either (i) pay cash to the Holder in an amount equal to the Holder's total purchase price (including brokerage
commissions, if any) for the shares of Common Stock so purchased (the "Buy-In Price"), at which point the Company's
obligation to deliver such certificate (and to issue such Warrant Shares) shall terminate, or (ii) promptly honor its obligation
to deliver to the Holder a certificate or certificates representing such Warrant Shares and pay cash to the Holder in an amount
equal to the excess (if any) of the Buy-In Price over the product of (A) such number of shares of Common Stock, times (B) the Closing
Bid Price on the date of exercise.


 


(d)    Cashless
Exercise.  Notwithstanding anything contained herein to the contrary, the Holder may exercise this Warrant in whole
or in part and, in lieu of making the cash payment otherwise contemplated to be made to the Company upon such exercise in payment
of the Aggregate Exercise Price, elect instead to receive upon such exercise the "Net Number" of shares of Common
Stock determined according to the following formula (a "Cashless Exercise"):


 


Net
Number = (A x B) - (A x C)


B


 


For
purposes of the foregoing formula:


 


A= the
total number of shares with respect to which this Warrant is then being exercised.


 


B= the
arithmetic average of the Closing Sale Prices of the shares of Common Stock (as reported by Bloomberg Financial Markets) for the
five (5) consecutive Trading Days ending on the Trading Day immediately preceding the date of the Exercise Notice.


 


C= the
Exercise Price then in effect for the applicable Warrant Shares at the time of such exercise.


 


Upon receipt of an Exercise Notice to which
this Section 1(d) is applicable, the Company shall notify the Holder within one (1) Trading Day of the calculation of the Net Number
of shares of Common Stock issuable upon the noticed exercise of the Warrant utilizing Cashless Exercise, and confirm the Holder’s
desire to complete the exercise of the Warrant pursuant to this Section 1(d).


 




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(e)    Rule
144. For purposes of Rule 144(d) promulgated under the Securities Act, as in effect on the date hereof, assuming the Holder
is not an affiliate of the Company, it is intended that the Warrant Shares issued in a Cashless Exercise shall be deemed to have
been acquired by the Holder, and the holding period for the Warrant Shares shall be deemed to have commenced, on the date this
Warrant was originally issued pursuant to the Purchase Agreement.


 


(f)    Disputes.
In the case of a dispute as to the determination of the Exercise Price or the arithmetic calculation of the Warrant Shares, the
Company shall promptly issue to the Holder the number of Warrant Shares that are not disputed.


 


(g) Beneficial
Ownership Limitation. Notwithstanding anything herein to the contrary, the Company shall not effect the exercise of this Warrant,
and the Holder shall not have the right to exercise this Warrant, to the extent that, after giving effect to such exercise, such
Person (together with such Person's affiliates, and any other Person whose beneficial ownership of Common Stock would be aggregated
with the Holder’s for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended (the “Exchange
Act”), and the applicable rules and regulations of the Securities and Exchange Commission (the “SEC”),
including any “group” of which the Holder is a member) would beneficially own a number of shares of Common Stock in
excess of the Beneficial Ownership Limitation (as defined below). For purposes of the foregoing sentence, the aggregate number
of shares of Common Stock beneficially owned by such Person and its affiliates shall include the number of shares of Common Stock
issuable upon exercise of this Warrant with respect to which the determination of such sentence is being made, but shall exclude
the number of shares of Common Stock which are issuable upon (i) exercise of the remaining, unexercised portion of this Warrant
beneficially owned by such Person and its affiliates and (ii) exercise or conversion of the unexercised or unconverted portion
of any other securities of the Company beneficially owned by such Person and its affiliates (including, without limitation, any
convertible notes, convertible stock or warrants) that are subject to a limitation on conversion or exercise analogous to the limitation
contained herein. Except as set forth in the preceding sentence, for purposes of this Section 1(g), beneficial ownership shall
be calculated in accordance with Section 13(d) of the Exchange Act, and the applicable rules and regulations of the SEC. In addition,
for purposes hereof, “group” has the meaning set forth in Section 13(d) of the Exchange Act and the applicable rules
and regulations of the SEC. For purposes of this Warrant, in determining the number of outstanding shares of Common Stock, the
Holder may rely on the number of outstanding shares of Common Stock as reflected in (1) the Company's most recent Form 10-K, Form
10-Q, Current Report on Form 8-K or other public filing with the SEC, as the case may be, (2) a more recent public announcement
by the Company or (3) a more recent notice by the Company or the Transfer Agent to the Holder setting forth the number of shares
of Common Stock then outstanding. For any reason at any time, upon the written or oral request of the Holder, the Company shall,
within two (2) Business Days of such request, confirm orally and in writing to the Holder the number of shares of Common Stock
then outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving effect to any
actual conversion or exercise of securities of the Company, including this Warrant, by the Holder and its affiliates since the
date as of which such number of outstanding shares of Common Stock was last publicly reported or confirmed to the Holder. The “Beneficial
Ownership Limitation” shall be [9.99] [4.99%] of the number of shares of the Common Stock outstanding immediately after
giving effect to the issuance of shares of Common Stock pursuant to such Exercise Notice (to the extent permitted pursuant to this
Section 1(g)). If the Holder has delivered an Exercise Notice, the Company shall be entitled to assume that such exercise will
not result in the Holder exceeding the Beneficial Ownership Limitation as a result of the exercise contemplated by such Exercise
Notice. [By written notice to the Company, the Holder may from time to time increase or decrease the Beneficial Ownership Limitation
to any other percentage not in excess of 19.9% specified in such notice; provided that (i) any such increase will not be
effective until the sixty-first (61st) day after such notice is delivered to the Company, and (ii) any such increase
or decrease will apply only to the Holder.]2 The provisions
of this Section 1(g) shall be construed, corrected and implemented in a manner so as to effectuate the intended beneficial ownership
limitation herein contained.


 








 






2
    Holder to elect to include or exclude this sentence.


 



 




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2.    ADJUSTMENT
OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES. The Exercise Price and the number of Warrant Shares shall be adjusted from
time to time as follows:


 


(a)    Adjustment
upon Subdivision or Combination of Common Stock. If the Company at any time on or after the Purchase Date subdivides (by any
stock split, stock dividend, recapitalization, reorganization, scheme, arrangement or otherwise) one or more classes of its outstanding
shares of Common Stock into a greater number of shares, the Exercise Price in effect immediately prior to such subdivision will
be proportionately reduced and the number of Warrant Shares will be proportionately increased. If the Company at any time on or
after the Purchase Date combines (by any stock split, stock dividend, recapitalization, reorganization, scheme, arrangement or
otherwise) one or more classes of its outstanding shares of Common Stock into a smaller number of shares, the Exercise Price in
effect immediately prior to such combination will be proportionately increased and the number of Warrant Shares will be proportionately
decreased. Any adjustment under this Section 2(a) shall become effective at the close of business on the date the subdivision or
combination becomes effective.


 


3.    RIGHTS
UPON DISTRIBUTION OF ASSETS. If the Company shall declare or make any dividend or other distribution of its assets (or rights
to acquire its assets) to holders of shares of Common Stock, by way of return of capital or otherwise (including, without limitation,
any distribution of cash, stock or other securities, property or options by way of a dividend, spin off, reclassification, corporate
rearrangement, scheme of arrangement or other similar transaction) (a "Distribution"), the Holder shall be entitled
to receive the dividend or distribution of assets that would have been payable to the Holder pursuant to the Distribution had the
Holder exercised this Warrant (or, if this Warrant has been partially exercised prior to the Distribution, any unexercised portion
thereof) immediately prior to such record date.


 




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4.    FUNDAMENTAL
TRANSACTIONS. If the Company enters into or becomes a party to any Fundamental Transaction, then the registered holder shall
have the right thereafter to receive, upon exercise of the Warrant, the same amount and kind of securities, cash or property as
it would have been entitled to receive upon the occurrence of such Fundamental Transaction if it had been, immediately prior to
such Fundamental Transaction, the holder of the number of Warrant Shares then issuable upon exercise in full of the Warrant without
regard to any limitations on exercise contained in the Warrant (the “Alternate Consideration”). The Company
shall not effect any such Fundamental Transaction unless prior to or simultaneously with the consummation thereof, any successor
to the Company, surviving entity or the corporation purchasing or otherwise acquiring such assets or other appropriate corporation
or Person shall assume the Warrant and the obligation to deliver to the registered holder, such Alternate Consideration as, in
accordance with the foregoing provisions, the registered holder may be entitled to receive, and the other obligations under the
Warrant. Notwithstanding the foregoing, except in connection with any Fundamental Transaction in which the consideration to be
paid for each share of Common Stock is at least 300% of the Exercise Price, at the request of the registered holder delivered at
any time commencing on the earlier to occur of the public disclosure of any Fundamental Transaction or the consummation of any
Fundamental Transaction through the date that is ninety (90) days after the later to occur of (i) the public disclosure of such
Fundamental Transaction, (ii) the consummation of such Fundamental Transaction and (iii) the registered holder becoming aware of
such Fundamental Transaction if such Fundamental Transaction was not publicly disclosed, the Company or the Successor Entity (as
the case may be) shall purchase the Warrant from the registered holder on the date of such request by paying to the registered
holder (x) in the case of a Cash-Out Fundamental Transaction or in the case of a Mixed Fundamental Transaction to the extent of
the percentage of the cash consideration in such Mixed Fundamental Transaction (determined in accordance with the definition of
a Mixed Fundamental Transaction), in cash equal to the Black Scholes Value, and (y) in the case of a Fundamental Transaction not
described in the foregoing subclause (x) or to the extent of the percentage of the consideration represented by securities of the
successor entity in a Mixed Fundamental Transaction (as determined in accordance with the definition of Mixed Fundamental Transaction),
in a number of shares of the Common Stock equal to the Black Scholes Value of the portion of this Warrant subject to redemption
under this clause (y) divided by ninety-five percent (95%) of the Closing Sale Price of the Common Stock on the Trading Day immediately
preceding the date on which the Fundamental Transaction is consummated.


 


5.    NONCIRCUMVENTION.
The Company hereby covenants and agrees that the Company will not, by amendment of its Certificate of Incorporation, Bylaws or
through any reorganization, transfer of assets, consolidation, merger, scheme of arrangement, dissolution, issue or sale of securities,
or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant, and will
at all times in good faith carry out all the provisions of this Warrant and take all action as may be required to protect the rights
of the Holder. Without limiting the generality of the foregoing, the Company (i) shall not increase the par value of any shares
of Common Stock receivable upon the exercise of this Warrant above the Exercise Price then in effect, (ii) shall take all
such actions as may be reasonably necessary or appropriate in order that the Company may validly and legally issue fully paid and
nonassessable shares of Common Stock upon the exercise of this Warrant, and (iii) shall, so long as this Warrant is outstanding,
take all action reasonably necessary to reserve and keep available out of its authorized and unissued shares of Common Stock, solely
for the purpose of effecting the exercise of this Warrant, 100% of the number of shares of Common Stock issuable upon exercise
of this Warrant then outstanding (without regard to any limitations on exercise).


 




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6.    WARRANT
HOLDER NOT DEEMED A STOCKHOLDER. Except as otherwise specifically provided herein, the Holder, solely in such Person's capacity
as a holder of this Warrant, shall not be entitled to vote or receive dividends or be deemed the holder of share capital of the
Company for any purpose, nor shall anything contained in this Warrant be construed to confer upon the Holder, solely in such Person's
capacity as the Holder of this Warrant, any of the rights of a stockholder of the Company or any right to vote, give or withhold
consent to any corporate action (whether any reorganization, issue of stock, reclassification of stock, consolidation, merger,
conveyance or otherwise), receive notice of meetings, receive dividends or subscription rights, or otherwise, prior to the issuance
to the Holder of the Warrant Shares which such Person is then entitled to receive upon the due exercise of this Warrant. In addition,
nothing contained in this Warrant shall be construed as imposing any liabilities on the Holder to purchase any securities (upon
exercise of this Warrant or otherwise) or as a stockholder of the Company, whether such liabilities are asserted by the Company
or by creditors of the Company.


 


7.    REISSUANCE
OF WARRANTS.


 


(a)    Transfer
of Warrant. If this Warrant is to be transferred (which may only be transferred in compliance with the Securities Purchase
Agreement), the Holder shall surrender this Warrant to the Company, whereupon the Company will forthwith issue and deliver upon
the order of the Holder a new Warrant (in accordance with Section 7(d)), registered as the Holder may request, representing the
right to purchase the number of Warrant Shares being transferred by the Holder and, if less then the total number of Warrant Shares
then underlying this Warrant is being transferred, a new Warrant (in accordance with Section 7(d)) to the Holder representing the
right to purchase the number of Warrant Shares not being transferred.


 


(b) Lost, Stolen
or Mutilated Warrant. Upon receipt by the Company of evidence reasonably satisfactory to the Company of the loss, theft, destruction
or mutilation of this Warrant, and, in the case of loss, theft or destruction, of any indemnification undertaking by the Holder
to the Company in customary form and, in the case of mutilation, upon surrender and cancellation of this Warrant, the Company shall
execute and deliver to the Holder a new Warrant (in accordance with Section 7(d)) representing the right to purchase the Warrant
Shares then underlying this Warrant.


 


(c)    Exchangeable
for Multiple Warrants. This Warrant is exchangeable, upon the surrender hereof by the Holder at the principal office of the
Company, for a new Warrant or Warrants (in accordance with Section 7(d)) representing in the aggregate the right to purchase the
number of Warrant Shares then underlying this Warrant, and each such new Warrant will represent the right to purchase such portion
of such Warrant Shares as is designated by the Holder at the time of such surrender; provided, however, that no Warrants for fractional
shares of Common Stock shall be given.


 





(d)    Issuance
of New Warrants. Whenever the Company is required to issue a new Warrant pursuant to the terms of this Warrant, such new Warrant
(i) shall be of like tenor with this Warrant, (ii) shall represent, as indicated on the face of such new Warrant, the right to
purchase the Warrant Shares then underlying this Warrant (or in the case of a new Warrant being issued pursuant to Section 7(a)
or Section 7(c), the Warrant Shares designated by the Holder which, when added to the number of shares of Common Stock underlying
the other new Warrants issued in connection with such issuance, does not exceed the number of Warrant Shares then underlying this
Warrant), (iii) shall have an issuance date, as indicated on the face of such new Warrant which is the same as the Issuance Date,
and (iv) shall have the same rights and conditions as this Warrant.


 






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8.    NOTICES.
Whenever notice is required to be given under this Warrant, unless otherwise provided herein, such notice shall be given in accordance
with Section 8.6 of the Purchase Agreement. The Company shall provide the Holder with prompt written notice of all actions taken
pursuant to this Warrant, including in reasonable detail a description of such action and the reason therefor.


 


9.    AMENDMENT
AND WAIVER. Except as otherwise provided herein, the provisions of this Warrant may be amended and the Company may take any
action herein prohibited, or omit to perform any act herein required to be performed by it, only if the Company has obtained the
written consent of the Holder.


 


10.    GOVERNING
LAW. This Warrant shall be governed by and construed and enforced in accordance with, and all questions concerning the construction,
validity, interpretation and performance of this Warrant shall be governed by, the internal laws of the State of New York, without
giving effect to any choice of law or conflict of law provision or rule (whether of the State of New York or any other jurisdictions)
that would cause the application of the laws of any jurisdictions other than the State of New York.


 


11.    CONSTRUCTION;
HEADINGS. This Warrant shall be deemed to be jointly drafted by the Company and the Holder and shall not be construed against
any person as the drafter hereof. The headings of this Warrant are for convenience of reference and shall not form part of, or
affect the interpretation of, this Warrant.


 


12.    DISPUTE
RESOLUTION. In the case of a dispute as to the determination of the Exercise Price or the arithmetic calculation of the Warrant
Shares, the Company shall submit the disputed determinations or arithmetic calculations, as the case may be, via facsimile within
two (2) Business Days of receipt of the Exercise Notice giving rise to such dispute to the Holder. If the Holder and the Company
are unable to agree upon such determination or calculation of the Exercise Price or the Warrant Shares within three Business Days
of such disputed determination or arithmetic calculation being submitted to the Holder, then the Company shall, within two (2)
Business Days submit via facsimile (a) the disputed determination of the Exercise Price to an independent, reputable investment
bank selected by the Company and approved by the Holder or (b) the disputed arithmetic calculation of the Warrant Shares to the
Company's independent, outside accountant. The Company shall cause at its expense the investment bank or the accountant, as the
case may be, to perform the determinations or calculations and notify the Company and the Holder of the results no later than ten
Business Days from the time it receives the disputed determinations or calculations. Such investment bank's or accountant's determination
or calculation, as the case may be, shall be binding upon all parties absent demonstrable error.


 




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13.    REMEDIES,
OTHER OBLIGATIONS, BREACHES AND INJUNCTIVE RELIEF. The remedies provided in this Warrant shall be cumulative and in addition
to all other remedies available under this Warrant, at law or in equity (including a decree of specific performance and/or other
injunctive relief), and nothing herein shall limit the right of the Holder to pursue actual damages for any failure by the Company
to comply with the terms of this Warrant.


 


14.    TRANSFER.    Subject
to the Purchase Agreement and compliance with all applicable securities laws, this Warrant may be offered for sale, sold, transferred
or assigned without the consent of the Company.


 


15.    CERTAIN
DEFINITIONS. For purposes of this Warrant, the following terms shall have the following meanings:


 


(a)    “Black
Scholes Value” means the value of the unexercised portion of the Warrant remaining on the date of the registered holder’s
request pursuant, which value is calculated using the Black Scholes Option Pricing Model obtained from the “OV” function
on Bloomberg utilizing (i) an underlying price per share equal to the greater of (1) the highest Closing Sale Price of the Common
Stock during the period beginning on the Trading Day immediately preceding the earlier to occur of the public disclosure or consummation
of the applicable Fundamental Transaction and ending on the Trading Day of the registered holder’s request pursuant to this
Section and (2) the sum of the price per share being offered in cash in the applicable Fundamental Transaction (if any) plus the
value of the non-cash consideration being offered in the applicable Fundamental Transaction (if any), (ii) a strike price equal
to the Exercise Price in effect on the of date of the Holder’s request pursuant to this Section, (iii) a risk-free interest
rate corresponding to the U.S. Treasury rate for a period equal to the greater of (1) the remaining term of the Warrant as of the
date of the Holder’s request pursuant to this Section and (2) the remaining term of this Warrant as of the date of consummation
of the applicable Fundamental Transaction or as of the date of the registered holder’s request pursuant to this Section if
such request is prior to the date of the consummation of the applicable Fundamental Transaction and (iv) an expected volatility
equal to the greater of 100% and the 30 day volatility obtained from the HVT function on Bloomberg (determined utilizing a 365
day annualization factor) as of the Trading Day immediately following the earlier to occur of the public disclosure or consummation
of the applicable Fundamental Transaction


 


(b)    "Bloomberg"
means Bloomberg Financial Markets.


 


(c)    "Business
Day" means any day other than Saturday, Sunday or other day on which commercial banks in The City of New York are authorized
or required by law to remain closed.


 


(d)    “Cash-Out
Fundamental Transaction” means a Fundamental Transaction in which the consideration payable to holders of the Common
Stock in connection with the Fundamental Transaction consists solely of cash.


 




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(e)    "Closing
Bid Price" and "Closing Sale Price" means, for any security as of any date, the last closing bid price
and last closing trade price, respectively, for such security on the Principal Market, as reported by Bloomberg, or, if the Principal
Market begins to operate on an extended hours basis and does not designate the closing bid price or the closing trade price, as
the case may be, then the last bid price or the last trade price, respectively, of such security prior to 4:00:00 p.m., New York
time, as reported by Bloomberg, or, if the Principal Market is not the principal securities exchange or trading market for such
security, the last closing bid price or last trade price, respectively, of such security on the principal securities exchange or
trading market where such security is listed or traded as reported by Bloomberg, or if the foregoing do not apply, the last closing
bid price or last trade price, respectively, of such security in the over-the-counter market on the electronic bulletin board for
such security as reported by Bloomberg, or, if no closing bid price or last trade price, respectively, is reported for such security
by Bloomberg, the average of the bid prices, or the ask prices, respectively, of any market makers for such security as reported
in the "pink sheets" by Pink Sheets LLC (formerly the National Quotation Bureau, Inc.). If the Closing Bid Price or the
Closing Sale Price cannot be calculated for a security on a particular date on any of the foregoing bases, the Closing Bid Price
or the Closing Sale Price, as the case may be, of such security on such date shall be the fair market value as mutually determined
by the Company and the Holder. All such determinations to be appropriately adjusted for any stock dividend, stock split, stock
combination or other similar transaction during the applicable calculation period.


 


(f)    "Common
Stock" means (i) the Company's shares of Common Stock, par value $0.001 per share, and (ii) any share capital
into which such Common Stock shall have been changed or any share capital resulting from a reclassification of such Common Stock.


 


(g)    "Eligible
Market" means the Principal Market, The New York Stock Exchange, Inc., The NASDAQ Global Select Market or The NASDAQ Capital
Market.


 


(h)    "Expiration
Date" means the date five (5) years after the Issuance Date or, if such date falls on a day other than a Business Day
or on which trading does not take place on the Principal Market (a "Holiday"), the next date that is not a Holiday.


 


(i)    "Fundamental
Transaction" means that the Company shall, directly or indirectly, in one or more related transactions, (i) consolidate
or merge with or into (whether or not the Company is the surviving corporation, unless the holders of the Company’s voting
power immediately prior to such transaction or series of related transactions continue after such transaction or series of related
transactions to have a majority of the voting power of the surviving entity) another Person, or (ii) sell, assign, transfer, convey
or otherwise dispose of all or substantially all of the properties or assets of the Company to another Person, or (iii) allow another
Person to make a purchase, tender or exchange offer that is accepted by the holders of more than the 50% of the outstanding shares
of Common Stock (not including any shares of Common Stock held by the Person or Persons making or party to, or associated or affiliated
with the Persons making or party to, such purchase, tender or exchange offer), or (iv) consummate a stock purchase agreement or
other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement)
with another Person whereby such other Person acquires more than 50% of the outstanding shares of Common Stock (not including any
shares of Common Stock held by the other Person or other Persons making or party to, or associated or affiliated with the other
Persons making or party to, such stock purchase agreement or other business combination), (v) reorganize, recapitalize or reclassify
its Common Stock, or (vi) any "person" or "group" (as these terms are used for purposes of Sections 13(d) and
14(d) of the Exchange Act) is or shall become the "beneficial owner" (as defined in Rule 13d-3 under the Exchange Act),
directly or indirectly, of 50% of the aggregate ordinary voting power represented by issued and outstanding Common Stock.


 




    	- 10 -



    	 



    

 


(j)    “Mixed
Fundamental Transaction” means a Fundamental Transaction where the consideration payable to stockholders of the Company
consists partially of cash and partially of securities of a successor entity. If the successor entity is a Publicly Traded Successor
Entity, the percentage of consideration represented by securities of such successor entity shall be equal to the quotient of (x)
the product of the aggregate anticipated number of shares of the Publicly Traded Successor Entity to be issued (based on the Trading
Day preceding the first public announcement of the Mixed Fundamental Transaction) to holders of the Common Stock of the Company
multiplied by the closing market price for such shares of the Publicly Traded Successor Entity on its principal securities exchange
on the Trading Day preceding the first public announcement of the Mixed Fundamental Transaction, divided by (y) the sum of the
amount determined in subclause (x) plus the aggregate value of other consideration, including cash consideration, in such Fundamental
Transaction. If the successor entity is not a Publicly Traded Successor Entity, the percentage of consideration represented by
securities of such successor entity shall be as mutually determined in good faith by the Holder and the Company's Board of Directors.


 


(k)    "Parent
Entity" of a Person means an entity that, directly or indirectly, controls the applicable Person and whose common stock
or equivalent equity security is quoted or listed on an Eligible Market, or, if there is more than one such Person or Parent Entity,
the Person or Parent Entity with the largest public market capitalization as of the date of consummation of the Fundamental Transaction.


 


(l)    "Person"
means an individual, a limited liability company, a partnership, a joint venture, a corporation, a trust, an unincorporated organization,
any other entity and a government or any department or agency thereof.


 


(m)    "Principal
Market" means NYSE MKT.


 


(n)    “Publicly
Traded Successor Entity” means a Successor Entity that is a publicly traded corporation whose common stock is quoted
on or listed for trading on the over the counter Bulletin Board, the New York Stock Exchange, Inc., the NYSE Arca, the NYSE MKT,
the NASDAQ Capital Market, the NASDAQ Global Market or the NASDAQ Global Select Market.


 


(o)    "Successor
Entity" means the Person (or, if so elected by the Holder, the Parent Entity) formed by, resulting from or surviving any
Fundamental Transaction or the Person (or, if so elected by the Holder, the Parent Entity) with which such Fundamental Transaction
shall have been entered into.


 


(p)    "Trading
Day" means any day on which the Common Stock are traded on the Principal Market, or, if the Principal Market is not the
principal trading market for the Common Stock, then on the principal securities exchange or securities market on which the Common
Stock is then traded; provided that "Trading Day" shall not include any day on which the Common Stock are scheduled
to trade on such exchange or market for less than 4.5 hours or any day that the Common Stock are suspended from trading during
the final hour of trading on such exchange or market (or if such exchange or market does not designate in advance the closing time
of trading on such exchange or market, then during the hour ending at 4:00:00 p.m., New York time).


 




    	- 11 -



    	 



    

 


    IN
WITNESS WHEREOF, the Company has caused this Warrant to Purchase Common Stock to be duly executed as of the Issuance Date set
out above.


 


	 	SYNTHETIC BIOLOGICS, INC.
	 	 	 
	 	By:	 
	 	 	Name:  Jeffrey Riley
	 	 	Title:  Chief Executive Officer


 


Warrant Signature Page


 




    	 



    	 



    

 


    EXHIBIT A


 


EXERCISE NOTICE


TO BE EXECUTED BY THE REGISTERED HOLDER
TO EXERCISE THIS


WARRANT TO PURCHASE COMMON STOCK


 


SYNTHETIC
BIOLOGICS INC.


 


The undersigned holder
hereby exercises the right to purchase _________________ of the shares of Common Stock ("Warrant Shares") of
SYNTHETIC BIOLOGICS, INC,
a Nevada corporation (the "Company"), evidenced by the attached Warrant to Purchase Common Stock (the "Warrant").
Capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Warrant.


 


1.
Form of Exercise Price. The Holder intends that payment of the Exercise Price shall be made as:


 


			____________    a "Cash Exercise" with respect to _________________
Warrant Shares; and/or



 


			____________    a "Cashless Exercise" with respect to _______________
Warrant Shares.



 


2.
Payment of Exercise Price. In the event that the holder has elected a Cash Exercise with respect to some or all of the Warrant
Shares to be issued pursuant hereto, the holder shall pay the Aggregate Exercise Price in the sum of $___________________ to the
Company in accordance with the terms of the Warrant.


 


3.
Delivery of Warrant Shares. The Company shall deliver to the holder __________ Warrant Shares in accordance with the terms of the
Warrant.


 


Date: _______________ __, ______


 


	 	 
	Name of Registered Holder	 


 


	By:	 	 
	 	Name:	 
	 	Title:	 


 




    	 



    	 



    

 


ACKNOWLEDGMENT


 


    The
Company hereby acknowledges this Exercise Notice and hereby directs Corporate Stock Transfer, Inc. to issue the above indicated
number of shares of Common Stock in accordance with the Transfer Agent Instructions dated October ____, 2014 from the Company and
acknowledged and agreed to by Corporate Stock Transfer, Inc.


 


	 	SYNTHETIC BIOLOGiCS, INC
	 	 	 
	 	By:	 
	 	 	Name:  Jeffrey Riley
	 	 	Title: Chief Executive Officer