EX-4.2



 Exhibit 4.2 

FIRST SUPPLEMENTAL INDENTURE dated as of March 21, 2014, between GlaxoSmithKline plc, a public limited company incorporated under the laws of
England and Wales (the “Company”) and Law Debenture Trust Company of New York, a company duly organized and existing under the laws of the State of New York (the “Trustee”). 

RECITALS 
 WHEREAS, the
Company and the Trustee entered into an indenture, dated as of March 4, 2008 (the “Indenture”), relating to the issuance from time to time by the Company of its Securities; 

WHEREAS, Section 10.01 of the Indenture provides, among other things, that a supplemental indenture may be entered into by the Company and the
Trustee, without notice to or the consent of any Holders, (i) to establish the terms of Securities of any series; and/or (ii) to make any change that does not materially and adversely affect the rights of any Holder of Securities outstanding prior
to the date of such supplemental indenture; 
 WHEREAS, the Company has requested the Trustee to join with it in the execution and delivery
of this first supplemental indenture (the “First Supplemental Indenture”) in order to supplement and amend the Indenture, solely with respect to Securities issued on or after the date hereof, to: (1) amend certain redemption provisions;
(2) amend certain covenants of the Company; and (3) amend the definition of “Event of Default”; in no event will the provisions of this First Supplemental Indenture affect the interests of the Holders of Securities of any series
outstanding prior to the date of this First Supplemental Indenture in any respect; 
 WHEREAS, the Company has determined that this First
Supplemental Indenture complies with said Section 10.01, does not affect the interests of any Holders of Securities outstanding prior to the date of this First Supplemental Indenture and does not require notice to or the consent of any Holders;
and 
 WHEREAS, the Company represents and warrants that all things necessary to make this First Supplemental Indenture a valid agreement of
the Company and the Trustee, in accordance with the terms of the Indenture, and a valid amendment of and supplement to the Indenture have been done; 

NOW, THEREFORE, THIS FIRST SUPPLEMENTAL INDENTURE WITNESSETH: 

For and in consideration of the premises and the mutual covenants contained herein and in the Indenture and for other good and valuable
consideration, the receipt and sufficiency of which are herein acknowledged, the Company and the Trustee hereby agree, for the equal and ratable benefit of the Holders, as follows: 







 ARTICLE I 

DEFINITIONS 

SECTION 1.01 Defined Terms. All capitalized terms used but not defined herein shall have the meanings ascribed to such terms in the
Indenture, as supplemented and amended hereby. All definitions in the Indenture shall be read in a manner consistent with the terms of this First Supplemental Indenture. 

SECTION 1.02 Additional Definitions. 

“Additional Amounts” has the meaning specified in Section 2.02 hereof. 

“EDGAR System” means the EDGAR filing system of the Commission and the rules and regulations pertaining thereto promulgated by the Commission in
Regulation S-T under the Securities Act and the Exchange Act, in each case as the same may be amended or succeeded from time to time (and without regard to format). 

“Taxes” has the meaning specified in Section 2.02 hereof. 

ARTICLE II 
 AMENDMENTS
TO THE INDENTURE 
 SECTION 2.01 Amendments to Section 3.01 Relating to Redemption. Section 3.01 of the Indenture is
amended, with respect to Securities outstanding under series created on or after the date hereof, to read as follows: 

“Section 3.01 Applicability of Article. Securities of any series that are redeemable before their maturity shall be
redeemable in accordance with their terms and (except as otherwise specified as contemplated by Section 2.03 of the Indenture for Securities of any series) in accordance with this Article Three. The provisions of this Article Three shall be
applicable to the Securities of any series, in whole but not in part, if, with respect to such series: 
 (a) the Company
determines that, as a result of any change in or amendment to the laws or any regulations or rulings promulgated thereunder of the United Kingdom (or of any political subdivision or taxing authority thereof), or any change in the application or
official interpretation of such laws, regulations or rulings, or any change in the application or official interpretation of, or any execution of or amendment to, any treaty or treaties affecting taxation to which any such jurisdiction is a party,
which change, execution or amendment becomes effective on or after the issue date or such other date specified in the Securities of such series, 

(i) the Company would be required to pay Additional Amounts (as defined in Section 4.05) with respect to such series of
Securities on the next succeeding interest payment date and the payment of such Additional Amounts cannot be avoided by the use of reasonable measures available to the Company, or 

  
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 (ii) withholding tax has been or would be required to be withheld with respect to
interest income received or receivable by the Company directly from any affiliate and such withholding tax obligation cannot be avoided by the use of reasonable measures available to the Company (or any affiliate); or 

(b) the Company determines, based upon an opinion of independent counsel of recognized standing that, as a result of any action
taken by any legislative body of, taxing authority of, or any action brought in a court of competent jurisdiction, in the United Kingdom (or of any political subdivision or taxing authority thereof) (whether or not such action was taken or brought
with respect to the Company), which action is taken or brought on or after the issue date or such other date specified in the Securities of such series, there is a substantial probability that the circumstances described in subsection (a) above
would exist; provided, however, that no such notice of redemption may be given earlier than 90 days prior to the earliest date on which the Company would be obligated to pay such Additional Amounts. The Company will also pay to each Holder, or make
available for payment to each such Holder, on the redemption date any Additional Amounts resulting from the payment of such redemption price.” 

SECTION 2.02 Amendments to Section 4.05 Relating to Payment of Additional Amounts. Section 4.05 of the Indenture is amended,
with respect to Securities outstanding under series created on or after the date hereof, to read as follows: 
 “Section
4.05 Payment of Additional Amounts. All payments of Principal and interest in respect of the Securities shall be free and clear of and without withholding or deduction for or on account of any present or future tax, duty, levy, impost, assessment or
other governmental charge of any nature whatsoever imposed or levied by or on behalf of the government of the United Kingdom or of any territory of the United Kingdom or by any authority or agency therein or thereof having the power to tax
(collectively, “Taxes”), except to the extent such Taxes are required to be withheld or deducted by law or by the interpretation or administration thereof. If the Company is so required to withhold or deduct any amount for or on account of
Taxes from any payment made in respect of the Securities, the Company shall pay such additional amounts (“Additional Amounts”) as may be necessary such that the net amount received by each Holder (including such Additional Amounts) after
such withholding or deduction shall not be less than the amount such Holder would have received if the Taxes had not been withheld or deducted; provided that no Additional Amounts will be payable with respect to Taxes: 

(a) that would not have been imposed but for the existence of any present or former connection between such Holder or
beneficial owner of the Securities (or between a fiduciary, settlor, beneficiary, member or shareholder of, or possessor of a power over, such Holder or beneficial owner, if such Holder or beneficial owner is an estate, trust, partnership or
corporation) and the United Kingdom or any political subdivision or territory or possession thereof or therein or area subject to its jurisdiction, including, without limitation, such Holder or beneficial owner (or such fiduciary, settlor,
beneficiary, member, shareholder or possessor) being or having been a citizen or resident thereof or treated as a resident thereof or domiciled thereof or a national thereof or being or having been present or engaged in trade or business therein or
having or having had a permanent establishment therein; 

  
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 (b) that are estate, inheritance, gift, sales, transfer, personal property,
wealth or similar taxes, duties, assessments or other governmental charges; 
 (c) that are payable other than by withholding
from payments of Principal of or interest on the Securities; 
 (d) that would not have been imposed but for the failure of
the applicable recipient of such payment to comply with any certification, identification, information, documentation or other reporting requirement to the extent such compliance is required by applicable law or administrative practice or an
applicable treaty as a precondition to exemption from, or reduction in, the rate of deduction or withholding of such Taxes; 

(e) that would not have been imposed but for the presentation of a Security (where presentation is required) for payment on a
date more than 30 days after the date on which such payment became due and payable or the date on which payment thereof was duly provided for, whichever occurred later; 

(f) that are imposed on a payment to an individual and are required to be made pursuant to European Council Directive
2003/48/EC or any other Directive implementing the conclusions of the ECOFIN Council meeting of November 26-27, 2000 on the taxation of savings income, or any law implementing or complying with, or introduced in order to conform to, such
Directive; 
 (g) that would not have been imposed if presentation for payment of the relevant Securities had been made to a
Paying Agent other than the Paying Agent to which the presentation was made; 
 (h) that would not have been imposed but for
a failure by the Holder or beneficial owner (or any financial institution through which the Holder or beneficial owner holds any Security through which payment on the Security is made) to comply with any certification, information, identification,
documentation or other reporting requirements (including entering into and complying with an agreement with the U.S. Internal Revenue Service or any other governmental authority) imposed pursuant to Sections 1471 through 1474 of the U.S. Internal
Revenue Code as in effect on the date of issuance of the Notes or any successor or amended version of such provisions, any agreement entered into pursuant to Section 1471(b) of the U.S. Internal Revenue Code, or any fiscal or regulatory
legislation, rules or practices adopted pursuant to any intergovernmental agreement entered into in connection with the implementation of such Sections of the U.S. Internal Revenue Code (or any law implementing such an intergovernmental agreement);
or 
 (i) any combination of the foregoing clauses (a) through (h); 

  
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 nor shall Additional Amounts be paid with respect to any payment of the Principal of or interest
on any Security to any such Holder who is a fiduciary or a partnership or a beneficial owner who is other than the sole beneficial owner of such payment to the extent a beneficiary or settlor with respect to such fiduciary or a member of such
partnership or a beneficial owner would not have been entitled to such Additional Amounts had it been the Holder of the Security. 

The Company shall maintain, in respect of Securities of each series outstanding, at least one Paying Agent located outside the
United Kingdom. In the event that a Paying Agent with respect to Securities of a particular series is maintained in any member state of the European Union, the Company shall maintain a Paying Agent in at least one member state that will not be
obliged to withhold or deduct taxes pursuant to any law implementing European Council Directive 2003/48/EC or any other Directive implementing the conclusions of the ECOFIN Council meeting of November 26-27, 2000 on the taxation of savings
income, provided there is at least one member state that does not require a paying agent to withhold or deduct pursuant to such Directive. 

The obligation of the Company to pay Additional Amounts if and when due will survive the termination of this Indenture and the
payment of all amounts in respect of the Securities.” 
 SECTION 2.03 Amendments to Section 4.08 Relating to Reports by the
Company. Paragraph (a) of Section 4.08 of the Indenture is amended, with respect to Securities outstanding under series created on or after the date hereof, to read as follows: 

“(a) file with the Trustee, within 15 days after the Company is required to file the same with the Commission, copies of the annual
reports and of the information, documents and other reports (or copies of such portions of any of the foregoing as the Commission may from time to time by rules and regulations prescribe) which the Company may be required to file with the Commission
pursuant to Section 13 or Section 15(d) of the Exchange Act; or, if the Company is not required to file information, documents or reports pursuant to either of such Sections, then it will file with the Trustee, in accordance with rules and
regulations prescribed from time to time by the Commission, such of the supplementary and periodic information, documents and reports which may be required pursuant to Section 13 of the Exchange Act in respect of a security listed and registered on
a national securities exchange as may be prescribed from time to time in such rules and regulations; provided that reports, information and documents filed by the Company with the Commission via the EDGAR System will be deemed filed with the Trustee
for purposes of this Section 4.08 as of the time that such reports, information and documents are filed via the EDGAR System;”. 

SECTION 2.04 Amendments to Section 7.01 Relating to Events of Default. 

(a) Paragraph (c) of Section 7.01 of the Indenture is amended, with respect to Securities outstanding under series created on or
after the date hereof, to replace the number “60” with “90.” 

  
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 (b) Paragraph (d) of Section 7.01 of the Indenture is amended, with respect to
Securities outstanding under series created on or after the date hereof, to read as follows: 
 “(d) default under any bond, debenture,
note or other evidence of indebtedness for money borrowed of the Company (not including any indebtedness for which recourse is limited to property purchased) having in any particular case an aggregate outstanding principal amount in excess of
£100,000,000 (or its equivalent in any other currency), whether such indebtedness now exists or shall hereafter be created, which default shall have resulted in such indebtedness becoming or being accelerated and declared due and payable prior
to the date on which it would otherwise have become due and payable, without such acceleration having been rescinded or annulled or such indebtedness having been discharged; provided that there shall not be deemed to be an Event of Default if such
acceleration is rescinded or annulled or such payment is made within 10 days after there has been given to the Company by the Trustee or to the Company and the Trustee by the Holders of 25% or more in aggregate principal amount of the Securities of
such series a written notice specifying such default and requiring it to be remedied and stating that such notice is a “Notice of Default” hereunder;”. 

ARTICLE III 
 GENERAL
PROVISIONS 
 SECTION 3.01 Trustee Makes No Representation. The recitals contained herein shall be taken as the statements of the
Company and the Trustee assumes no responsibility for the correctness of same. The Trustee makes no representation as to the validity of this First Supplemental Indenture. 

SECTION 3.02 Effect of the First Supplemental Indenture. This First Supplemental Indenture supplements the Indenture and shall be a part,
and subject to all the terms, thereof. The Indenture, as supplemented and amended by this First Supplemental Indenture, is in all respects ratified and confirmed, and the Indenture and the First Supplemental Indenture shall be read, taken and
construed as one and the same instrument; provided, however, that any provision in this First Supplemental Indenture which conflicts with any corresponding provision in the Indenture shall replace such conflicting terms in the Indenture in their
entirety, to the extent that such terms relate to any Securities issued hereafter. All provisions included in this First Supplemental Indenture supersede any conflicting provisions included in the Indenture unless not permitted by law. 

SECTION 3.03 Counterparts. This First Supplemental Indenture may be executed in any number of counterparts, each of which so executed
shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument. 
 SECTION 3.04
Trust Indenture Act. The Company hereby certifies that this First Supplemental Indenture conforms to the current requirements of the Trust Indenture Act. 

SECTION 3.05 Governing Law; Waiver of Jury Trial. The laws of the State of New York shall govern this First Supplemental Indenture. Each
of the Company and the Trustee hereby irrevocably waives, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to this First Supplemental Indenture. 

  
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 IN WITNESS WHEREOF, the parties hereto have caused this First Supplemental Indenture to be duly
executed, all as of the date first written above. 
  

					
	GLAXOSMITHKLINE PLC,
as Issuer	  	 
			
	 By:
	  	 /s/ Simon Dingemans
	  	
		  	 Name: Simon Dingemans
	  	
		  	 Title: Chief Financial Officer
	  	
	
	 LAW DEBENTURE TRUST COMPANY OF NEW YORK,

as Trustee

			
	 By:
	  	 /s/ James Heaney
	  	
		  	 Name: James Heaney
	  	
		  	 Title: Managing Director