BIOMARIN PHARMACEUTICAL INC. 1.875% SENIOR SUBORDINATED CONVERTIBLE NOTES DUE 2017

Exhibit 4.2

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN. THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE AND, UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY.

B IO M ARIN P HARMACEUTICAL I NC .

1.875% S ENIOR S UBORDINATED C ONVERTIBLE N OTES DUE 2017

N O . A1 CUSIP: 09061G AD3

BioMarin Pharmaceutical Inc., a Delaware corporation, promises to pay to Cede & Co. or registered assigns the principal amount of Three Hundred Twenty Four Million Eight Hundred Seventy Five Thousand Dollars ($324,875,000) on April 23, 2017.

This Security shall bear interest as specified on the other side of this Security. This Security is convertible as specified on the other side of this Security.

Additional provisions of this Security are set forth on the other side of this Security.

Dated: April 23, 2007

[SIGNATURE PAGE FOLLOWS]

Promise to Pay - 1 of 2

IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed as of April 23, 2007.

Promise to Pay - 2 of 2

B IO M ARIN P HARMACEUTICAL I NC .

1.875% S ENIOR S UBORDINATED C ONVERTIBLE N OTES DUE 2017

The Company promises to pay interest on the principal amount of this Note at the rate of 1.875% per annum. The Company shall pay interest semiannually in arrears on April 23 and October 23 of each year (each, an “Interest Payment Date”), commencing on October 8, 2007. Interest on the Notes shall accrue from the most recent date to which interest has been paid or, if no interest has been paid, from April 23, 2007; provided, however , that if there is not an existing default in the payment of interest and if this Note is authenticated between a record date referred to on the face hereof and the next succeeding Interest Payment Date, such Interest Payment Date. Interest will be computed on the basis of a 360-day year composed of twelve 30-day months.

If the Holder elects to require the Company to repurchase this Security pursuant to Section 5 of this Security, on a date that is after the Regular Record Date and prior to the corresponding Interest Payment Date, interest, including Special Interest, if any, accrued and unpaid hereon to, but not including, the applicable Fundamental Change Repurchase Date, will be paid to the Holder in whose name the Securities are registered as of the close of business on the Regular Record Date immediately preceding the applicable Fundamental Change Repurchase Date.

A Holder of any Security at the close of business on a Regular Record Date shall be entitled to receive interest, including Special Interest, if any, on such Security on the corresponding Interest Payment Date. A Holder of any Security which is converted after the close of business on a Regular Record Date and prior to the corresponding Interest Payment Date (other than any Security whose Maturity is prior to such Interest Payment Date) shall be entitled to receive interest, including Special Interest, if any, on the principal amount of such Security, notwithstanding the conversion of such Security prior to such Interest Payment Date. However, any such Holder which surrenders any such Security for conversion during the period between the close of business on such Regular Record Date and ending with the opening of business on the corresponding Interest Payment Date shall be required to pay the Company an amount equal to the interest, including Special Interest, if any, on the principal amount of such Security so converted (but excluding any overdue interest, including Special Interest, if any, on the principal amount of such Security so converted that exists at the time such Holder surrenders such Security for conversion), which is payable by the Company to such Holder on such Interest Payment Date, at the time such Holder surrenders such Security for conversion. Notwithstanding the foregoing, any such Holder which surrenders for conversion any Security (a) with respect to which the Company has specified a Fundamental Change Repurchase Date that is after such Regular Record Date and on or prior to the next succeeding Interest Payment Date, or (b) after the last Regular Record Date prior to the Final Maturity Date, in either case, shall be entitled to receive (and retain) such interest, including Special Interest, if any, and need not pay the Company an amount equal to the interest, including Special Interest, if any, on the principal amount of such Security so converted at the time such Holder surrenders such Security for conversion.

Form of Reverse Side of Security

Page 1

The Company shall pay interest, including Special Interest, if any, on this Security (except defaulted interest) to the person who is the Holder of this Security at the close of business on April 8 and October 8, as the case may be, (each, a “Regular Record Date”) immediately preceding the related Interest Payment Date. The Holder must surrender this Security to a Paying Agent to collect payment of principal. The Company will pay principal and interest and Special Interest, if any, in money of the United States that at the time of payment is legal tender for payment of public and private debts. The Company may pay principal and interest, including Special Interest, if any, in respect of any Certificated Security by check or wire transfer payable in such money; provided, however , that a Holder with an aggregate principal amount in excess of $5,000,000 will be paid by wire transfer in immediately available funds at the election of such Holder if such Holder has provided wire transfer instructions to the Trustee at least 10 Business Days prior to the Payment Date. The Company may mail an interest check to the Holder’s registered address. Notwithstanding the foregoing, so long as this Security is registered in the name of a Depositary or its nominee, all payments hereon shall be made by wire transfer of immediately available funds to the account of the Depositary or its nominee.

Any wire transfer instructions received by the Trustee will remain in effect until revoked by the Holder.

Initially, Wilmington Trust Company (the “Trustee,” which term shall include any successor trustee under the Indenture hereinafter referred to) will act as Paying Agent, Registrar and Conversion Agent. The Company may change any Paying Agent, Registrar or Conversion Agent without notice to the Holder. The Company or any of its Subsidiaries may, subject to certain limitations set forth in the Indenture, act as Paying Agent or Registrar.

This Security is one of a duly authorized issue of Securities of the Company designated as its 1.875% Senior Subordinated Convertible Notes Due 2017 (the “Securities”), issued under an Indenture dated as of March 29, 2006 (the “Base Indenture”), as supplemented by the Second Supplemental Indenture dated April 23, 2007 (the “Second Supplemental Indenture” and together with the Base Indenture, the “Indenture”), between the Company and the Trustee. The terms of this Security include those stated in the Indenture and those required by or made part of the Indenture by reference to the Trust Indenture Act of 1939, as amended, as in effect on the date of the Indenture. This Security is subject to all such terms, and the Holder of this Security is referred to the Indenture and said Act for a statement of them.

The Securities are senior subordinated unsecured obligations of the Company limited to $324,875,000 in aggregate principal amount at maturity. The Indenture does not limit the incurrence of other debt of the Company or its existing or future Subsidiaries, secured or unsecured.

Form of Reverse Side of Security

Page 2

If a Fundamental Change occurs, at the option of the Holder and subject to the terms and conditions of the Indenture, the Company shall become obligated to purchase for cash, subject to certain exceptions described in the Indenture all or any part specified by the Holder (so long as the principal amount of such part is $1,000 or an integral multiple of $1,000) of the Securities held by such Holder on a date specified by the Company that is no later than 30 days after the date of the Fundamental Change Company Notice, at a purchase price equal to 100% of the principal amount thereof together with unpaid interest, including Special Interest, if any, accrued to, but excluding, the Fundamental Change Repurchase Date. A Fundamental Change Company Notice shall be given by the Company to the Holders as provided in the Second Supplemental Indenture. To exercise such repurchase right, a Holder must deliver to the Trustee a Fundamental Change Repurchase Notice as provided in the Second Supplemental Indenture.

Subject to and upon compliance with the provisions of the Indenture, a Holder may surrender for conversion any Security that is $1,000 principal amount or integral multiples thereof.

Subject to certain conditions provided for in the Second Supplemental Indenture, in certain circumstances, a Holder may receive an amount in Common Stock equal to the Make Whole Premium, in addition to the shares of Common Stock issuable upon conversion of such Security.

The Conversion Rate shall be initially equal to 49.1171 shares of Common Stock per $1,000 principal amount of Securities. The Conversion Rate shall be adjusted under certain circumstances as provided in the Indenture.

No fractional share of Common Stock shall be issued upon conversion of a Security. Instead, the Company shall pay a cash adjustment as provided in the Indenture.

The Indebtedness evidenced by this Security is, to the extent and in the manner provided in the Indenture, subordinated and subject in right of payment to the prior payment in full of all amounts