TRANSORAL PHARMACEUTICALS, INC. WARRANT TO PURCHASE SHARES

Exhibit 4.2

On March 21, 2005, Transcept Pharmaceuticals, Inc. (“TPI”) issued warrants in connection with a bridge financing to the individuals and entities listed below (the “Warrants”). The form of Warrant used is set forth below as part of this Exhibit 4.2.

On January 30, 2009, TPI and Novacea, Inc. (“Novacea”) completed a merger (the “Merger”) whereby TPI became a wholly owned subsidiary of Novacea, and Novacea changed its name to “Transcept Pharmaceuticals, Inc.” (with such post-closing entity being referred to as “Transcept”). In connection with the Merger, the Warrants became exercisable for shares of Transcept common stock at the same exchange rate used in the Merger to exchange outstanding TPI capital stock (0.14134 shares of Transcept common stock for each exchanged share of TPI). The share numbers set forth below reflect the approximate post-Merger shares into which such Warrants may be exercised. The exercise price per share for the Warrants was similarly adjusted, and, as of the closing of the Merger, was approximately $1.415 per share of Transcept common stock.

THIS WARRANT AND THE SECURITIES ISSUABLE UPON THE EXERCISE HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED, HYPOTHECATED, OR OTHERWISE TRANSFERRED EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933, AS AMENDED OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT REGISTRATION IS NOT REQUIRED.

TRANSORAL PHARMACEUTICALS, INC.

WARRANT TO PURCHASE SHARES

Issuance Date: March 21, 2005

This Warrant is issued to                              by TransOral Pharmaceuticals, Inc., a Delaware corporation (the “ Company ”), pursuant to the terms of that certain Note and Warrant Purchase Agreement (the “ Note Purchase Agreement ”) of even date herewith, in connection with the Company’s issuance to the holder of this Warrant of a Subordinated Convertible Promissory Note (the “ Note ”).

1. Purchase of Shares . Subject to the terms and conditions hereinafter set forth and set forth in the Note Purchase Agreement, the holder of this Warrant is entitled, upon surrender of this Warrant at the principal office of the Company (or at such other place as the Company shall notify the holder hereof in writing), to purchase from the Company up to the number of fully paid and nonassessable Shares (as defined below), that equals the quotient obtained by dividing (a) the Warrant Coverage Amount (as defined below) by (b) the Exercise Price (as defined below).

2. Definitions .

(a) Exercise Price . The exercise price for the Shares shall be the price per share of equity securities sold to investors in a Qualified Equity Financing; provided, that in the event that a Qualified Equity Financing does not occur on or prior to December 31, 2005, the Holder may elect to exercise this Warrant for shares of Series B Preferred Stock at an exercise price of $0.20 per share (as adjusted for any stock splits, stock dividends, reclassifications or the like).

(b) Exercise Period . This Warrant shall be exercisable, in whole or in part, during the term commencing on the closing date of a Qualified Equity Financing (as defined below) and ending on the expiration of this Warrant pursuant to Section 12 hereof; provided, that in the event that a Qualified Equity Financing does not occur on or prior to December 31, 2005, this Warrant may, at the option of the Holder, be exercisable for shares of Series B Preferred Stock commencing January 1, 2006.

-1-

(c) Warrant Coverage Amount . The term “ Warrant Coverage Amount ” shall mean that amount which equals 25% of the principal amount of the Note.

(d) The Shares . The term “ Shares ” shall mean the class and series of preferred stock issued to investors in a Qualified Equity Financing; provided, that in the event that a Qualified Equity Financing does not occur on or prior to December 31, 2005, “ Shares ” shall mean, at the option of the Holder, the Series B Preferred Stock of the Company.

(e) Qualified Equity Financing . The term “ Qualified Equity Financing ” is an equity financing pursuant to which the Company sells shares of a new series of preferred stock with an aggregate sales price of not less than $10,000,000, including any and all convertible bridge notes (including Notes issued under the Note Purchase Agreement) which are converted into preferred stock and with the principal purpose of raising capital.

(f) Acquisition . The term “ Acquisition ” shall mean (i) any consolidation or merger involving the Company pursuant to which the Company’s stockholders own less than fifty percent (50%) of the voting securities of the surviving entity or (ii) the sale of all or substantially all of the assets of the Company; provided, that an Acquisition shall not include a merger effected exclusively for the purpose of changing the domicile of the Company or an equity financing in which the Company is the surviving corporation.

3. Method of Exercise . While this Warrant remains outstanding and exercisable the Holder may exercise, in whole or in part, the purchase rights evidenced hereby. Such exercise shall be effected by:

(a) the surrender of the Warrant, together with the notice of exercise in the form attached hereto as Exhibit A to the President of the Company at its principal offices; and

(b) the payment to the Company of an amount equal to the aggregate Exercise Price for the number of Shares being purchased.

4. Net Exercise . In lieu of cash exercising this Warrant, the holder of this Warrant may elect to receive shares equal to the value of this Warrant (or the portion thereof being canceled) by surrender of this Warrant at the principal office of the Company together with notice of such election, in which event the Company shall issue to the holder hereof a number of Shares computed using the following formula:

Where

X — The number of Shares to be issued to the holder of this Warrant.

Y — The number of Shares purchasable under this Warrant.

A — The fair market value of one Share.

B — The Exercise Price (as adjusted to the date of such calculations).

-2-

For purposes of this Section 4, the fair market value of a Share shall mean the average of the closing bid and asked prices of Shares quoted in the over-the-counter market in which the Shares are traded or the closing price quoted on any exchange on which the Shares are listed, whichever is applicable, as published in the Western Edition of The Wall Street Journal for the ten (10) trading days prior to the date of determination of fair market value (or such shorter period of time during which such stock was traded over-the-counter or on such exchange). If the Shares are not traded on the over-the-counter market or on an exchange, the fair market value shall be the price per Share that the Company could obtain from a willing buyer for Shares sold by the Company from authorized but unissued Shares, as such prices shall be determined in good faith by the Company’s Board of Directors.

5. Certificates for Shares . Upon the exercise of the purchase rights evidenced by this Warrant, one or more certificates for the number of Shares so purchased shall be issued as soon as practicable thereafter.

6. Issuance of Shares . The Company covenants that the Shares, when issued pursuant to the due exercise of this Warrant, will be duly and validly issued, fully paid and nonassessable and free from all taxes, liens, and charges with respect to the issuance thereof (other than any encumbrances created by or imposed upon the Holder).

7. Adjustment of Exercise Price and Number of Shares . The number of and kind of securities purchasable upon exercise of this Warrant and the Exercise Price shall be subject to adjustment from time to time as follows:

(a) Subdivisions, Combinations and Other Issuances . If the Company shall at any time prior to the expiration of this Warrant subdivide the Shares, by split-up or otherwise, or combine its Shares, or issue additional shares of its Shares as a dividend, the number of Shares issuable on the exercise of this Warrant shall forthwith be proportionately increased in the case of a subdivision or stock dividend, or proportionately decreased in the case of a combination. Appropriate adjustments shall also be made to the purchase price payable per share, but the aggregate purchase price payable for the total number of Shares purchasable under this Warrant (as adjusted) shall remain the same. Any adjustment under this Section 7(a) shall become effective at the close of business on the date the subdivision or combination becomes effective, or as of the record date of such dividend, or in th