CODEINE PHOSPHATE
`
`Farid J. Muhtadi
`and
`Mahmoud M . A. Hassan
`
`1. Description
`1.1 Nomenclature
`1.2 Formulae
`1.3 Molecular Weight
`1.4 Elemental Composition
`Appearance, Color, Odor, and Taste
`1.5
`2. Physical Properties
`2.2 Solubility
`2.3 Dissociation Constant
`2.4 Optical Rotation
`2.5 Sptctral Properties
`3. Preparation
`3.1 Isolation of Codeine
`3.2 Formation of Codeine Phosphate
`4. Synthesis of Codeine Phosphate
`4.1 Total Synthesis of Codeine
`Partial Synthesis of Codeine
`4 2
`5 . Biosynthesis of Codeine
`6. Metabolism
`7. Methods of Analysis
`Identification Tests
`7.1
`7.2 Microcrystal Tests
`7.3 Titrimetric Methods
`7.4 Complexometry
`7.5 Spectrophotometry
`7.6 Chromatography
`8. References
`
`94
`94
`94
`96
`96
`97
`97
`101
`101
`101
`103
`110
`110
`112
`112
`112
`113
`117
`120
`120
`120
`122
`123
`124
`125
`127
`134
`
`ANALYTICAL PROFILE5 OF DRUG SUBSTAKCES, 10
`
`93
`
`Copyright @) 1981 b) Academic Press. Inc
`All rights of reproduction iii any form rerencd.
`ISBN 0-12-260810-l1
`
`Merck Exhibit 2188, Page 1
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`IPR2020-00040
`
`

`

`94
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`1. Description
`
`1.1. Nomenclature
`
`1.1.1 Chemical Names
`
`(a) 7,8-Didehydro-4,5 CI -epoxy-3-methoxy-
`17-me thylmorphinan-6 a -01 -phosphate
`(1 : 1) (salt).
`
`(b) Morphinan-6-01, 7,8-didehydro-4,5-
`epoxy-3-methoxy-l7methyl-, ( 5 a , 6 a)
`phosphate (1 : 1) (salt).
`
`1.1.2 Generic Names
`
`Codeine phosphate ; Morphine-3-methyl ether
`phosphate; Methylmorphine phosphate; Morphine
`monomethyl ether phosphate.
`
`1.2. Formulae
`
`1.2.1 Emprical: C18H24N07P.
`C H NO P. $H20
`18 24 7
`
`(Anhydrous)
`
`(Hemihyd -
`rate)
`C H NO P. 312 H20 (Sesquihyd-
`18 24 7
`rate)
`
`1.2.2 Structural
`
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`

`

`CODEINE PHOSPHATE
`
`95
`
`More than twenty s t r u c t u r e s were proposed f o r
`morphine and o t h e r r e l a t e d phenanthrene a l k a -
`l o i d s . The c u r r e n t l y accepted s t r u c t u r e i s
`t h a t proposed i n 1925 by Gulland and Robinson
`(1). The proposed s t r u c t u r e w a s confirmed by
`t h e t o t a l s y n t h e s i s of morphine i n 1956 which
`w a s acheived by Gates and Tschudi ( 2 ) .
`
`1.2.3 CAS no.
`
`codeine phosphate t r i h e m i h y d r a t e
`[ 52-28-81
`(C18H21N03. H3P04.3/2 H20)
`
`1.2.4 Wiswesser Line Notation
`
`TB6 566 B6/CO 4ABBC R
`BX H 0 PN DU GHT & & TTJ
`FQ
`J O 1 P & QH 6r H3-P-04
`
`1.2.5 Stereochemistry
`
`Codeine p o s s e s s e s f i v e d i f f e r e n t asym-
`metric c g n t r e s ( a t C 59 c69 cg9 c13 and c14),
`b u t s i n c e t h e bridged r i n g system imposes
`some r i g i d i t y upon t h e system, t h e t h e o r e t i -
`cal number of o p t i c a l isomers i s l i m i t e d
`t o s i x t e e n . The d e d u c t i o n of r e l a t i v e con-
`f i g u r a t i o n s a t t h e v a r i o u s c e n t r e s by
`chemical methods has been w e l l summarized
`by Ginsburg ( 3 ) .
`
`The a b s o l u t e s t e r e o c h e m i s t r y has been
`deduced from a combination of X-ray c r y s t a l -
`lography and chemical d e g r a d a t i o n and
`c o r r e l a t i o n I.
`
`From t h e X-ray d a t a of morphine hydro-
`i o d i d e d i h y d r a t e (4) and of codeine hydro-
`bromide d i h y d r a t e (5,6) i t was concluded
`t h a t t h e molecules are approximately T-shaped,
`w i t h atoms of r i n g s A and B and t h e o x i d e
`r i n g l y i n g n e a r one plane, and t h e atoms of
`r i n g s C(cycloa1kene r i n g ) and D ( p i p e r i d i n e
`r i n g ) l y i n g c l o s e t o a second p l a n e a t r i g h t
`a n g l e s t o t h e f i r s t . The B/C r i n g j u n c t i o n
`w a s shown t o be c i s , and p i p e r i d i n e r i n g , D,
`
`Merck Exhibit 2188, Page 3
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`
`

`

`96
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`t o b e a n almost r e g u l a r chair-shape, w i t h t h e
`methyl group a t t a c h e d t o n i t r o g e n by an
`e q u a t o r i a l bond. The cycloalkene r i n g C i s
`almost boat-shaped, and t h e C -oxygen and C -
`5
`6
`hydroxyl group are c i s t o each o t h e r ( 7 ) .
`
`The a b s o l u t e geometry of t h e e n t i r e
`molecule 11, follows from i t s r e l a t i v e
`s t e r e o c h e m i s t r y and has been confirmed by
`o p t i c a l r o t a t o r y d i s p e r s i o n s t u d i e s ( 8 ) .
`
`\
`OH
`
`II
`
`1.3 Molecular Weight:-
`
`Anhydrous
`Hemihydrate
`Sesqu i hyd ra t e
`
`397.37
`406.36
`424.37
`
`1.4
`
`Elemetal Composition:
`
`Anhydr Gus
`
`C , 54.41% ; H, 6.05% ; 0, 28,18% ; P , 7.80%
`N, 3 . 5 6 % .
`Hemihydrate
`C , 53.20% ; H , 6.16 ; N , 3.45% : 0 , 29.56% ,
`P, 7.63%
`
`Se squ ihydr a t e
`
`C, 50.94% ; H, 6.37% ; N, 3.30% ; 0 , 32.08; P,7.31%
`
`Merck Exhibit 2188, Page 4
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`IPR2020-00040
`
`

`

`CODEINE PHOSPHATE
`
`97
`
`1 . 5 Appearance, Color, Odor and Taste:-
`
`Codeine phosphate o c c u r s i n two forms, one
`c o n t a i n i n g % molecule of water of c r y s t a l i z a t i o n and
`t h e o t h e r c o n t a i n i n g 1% molecule of water of
`c r y s t a l i z a t i o n .
`I t i s o d o r l e s s and h a s a b i t t e r
`taste.
`
`H e m i hyd r a t e
`
`F i n e , w h i t e , n e e d l e shaped c r y s t a l s o r white c r y s t a l -
`l i n e powder.
`
`Sesquihydrate
`
`Very e f f l o r e s c e n t , small c r y s t a l s o r c r y s t a l l i n e
`powder.
`
`2. P h y s i c a l P r o p e r t i e s
`
`2.1.1 X-ray D i f f r a c t i o n
`
`The stereochemical c o n f i g u r a t i o n of t h e
`codeine molecule was determined by Lindsey and
`Barnes (5) by a two d i m e n s t i o n a l s t u d y of codeine
`hydrobromide d i h y d r a t e . A t h r e e d i m e n s t i o n a l
`s t u d y of t h e s a l t h a s been a l s o c a r r i e d o u t by
`Kartha e t a 1 (6).
`I n t e r a t o m i c d i s t a n c e s and bond
`a n g l e s are l i s t e d i n Tables 1 and 2 r e s p e c t i v e l y .
`The codeine molecule i n i t s a b s o l u t e c o n f i g u r a t i o n
`is r e p r e s e n t e d i n Fig. 1.
`
`0
`Table 1. I n t e r a t o m i c D i s t a n c e s (A )
`
`I n t r a m o l e c u l a r
`
`
`
`1
`
`CHI-O
`3
`'1-'3
`'3-'2
`c2-c1
`cl-cll
`cll-c12
`
`'1 2-'4
`c4-c3
`
`1.443
`1.399
`1.372
`1.401
`1.387
`1.399
`1.369
`1.388
`
`(1.58)
`(1.49)
`(1.45)
`(1.34)
`(1.30)
`(1.40)
`(1.32)
`(1.37)
`
`C14-C8
`C8-C7
`C7-Cg
`C6-C5
`C6-OH
`
`C14-C9
`C9-Cl0
`Cl0-Cl1
`
`1.497
`1.324
`1.531
`1.516
`1.427
`1.561
`1.539
`1.496
`
`(1.48)
`(1.31)
`(1.49)
`(1.59)
`(1.46)
`(1.59)
`(1.63)
`(1.52)
`
`Merck Exhibit 2188, Page 5
`Mylan Pharmaceuticals Inc. v. Merck Sharp & Dohme Corp.
`IPR2020-00040
`
`

`

`CODEINE PHOSPHATE
`
`98
`
`F i g . 1. Model showing t h e a b s o l u t e c o n f i g u r a t i o n of
`t h e c o d e i n e m o l e c u l e ( o n l y t h o s e H'5 on C
`5'
`C 6 , C g , C I 4 a r e shown).
`
`Merck Exhibit 2188, Page 6
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`

`

`CODEINE PHOSPHATE
`
`c -0 4 2
`0 -c 2 5
`c -c 5 13
`'13-'12
`'13-'14
`
`c -c 1 7
`'2-'7
`C3-H20'
`C4-H20'
`C5-Br
`C6-N
`c -c 7 12
`C -H 0"
`8 2
`
`1.370
`1.472
`1.532
`1.504
`1.564
`
`3.716
`3.728
`3.561
`3.528
`3.728
`3.817
`3.638
`
`3.393
`
`(1 -45) C13-C15
`c15-c16
`
`(1.62)
`(1.54)
`(1.58)
`
`C16-N
`N-Cg
`
`N-CH3"
`
`1.535
`1.530
`1.468
`1.521
`1.506
`
`Intermolecular
`
`3.577
`Cg-OH
`C10-H20" 3.680
`C11-C7 3.722
`C12-C7 3.638
`C13-H20' 3.834
`C14-H20' 3.543
`C15-OH 3.644
`
`1 6-'2
`CH3 -H20"
`c ~ ~ ' l - 0 ~
`N-C
`6
`
`'1-'15
`02-H20'
`OH-CH;'
`
`rable 2. Bond angles (g)
`
`CH -0 -C
`3 1 3
`0 -c -c
`1 3 4
`0 -c -c
`1 3 2
`c -c -c
`4 3 2
`c -c -c
`3 2 1
`c -c -c
`2 1 11
`Y C 1 l-cl 2
`o-cll-cl
`c1 0-cll-c12
`'1 1-'12-'4
`1 3-'12-'11
`'1 3-'12-'4
`'1 2-'4-'3
`'1 3-'12-'2
`
`117.2
`114.5
`127.3
`
`118.2
`120.2
`
`122.5
`115.2
`125.8
`118.6
`122.7
`
`127.3
`109.4
`120.8
`111.9
`
`(1 12) c1 2-c13-c1 4
`(1 11) c1 5-c13-c14
`(129) c5-Cl3-Cl4
`(1 19) c1 2-c13-c1 5
`(115) c13-c14-c8
`
`(129) cl3-cl4-Cg
`
`(113) C8-Cl4-C9
`(129) C13-C15-C16
`(118) C15-C16-N
`(1 25) C1 6-N-Cg
`(126) C16-N-CH3"
`(1 09) C9-N-CH3"
`(118) N-Cg-C14
`(115) N-C -C 9 10
`
`105.5
`108.4
`116.9
`112.2
`108.1
`107.8
`112.5
`112.6
`110.7
`113.6
`110.4
`113.1
`105.2
`113.0
`
`Merck Exhibit 2188, Page 7
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`

`100
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`
`
`
`c -c -0
`3
`4
`2
`c -0 -c
`4
`2
`5
`O2-'5-'13
`c6'c5-c13
`c -c -0
`6
`5
`2
`'5-'13-'12
`c5-c13'c1 5
`
`
`
`127.0
`107.7
`105.1
`112.8
`111.0
`101.3
`112.4
`
`(126)
`(102)
`(1 08)
`(118)
`(119)
`(96)
`
`Cl4-Cg-Cl0
`C -C
`-C
`9 10 11
`C5-C6-OH
`C7-C6-OH
`C5-Cg-C7
`C6-C7-C8
`
`(119)
`
`C7-C8-C14
`
`114.0
`115.4
`112.5
`111.2
`113.9
`119.8
`120.6
`
`(109)
`(119)
`(104)
`(107)
`(100)
`(123)
`(118)
`
`The intramolecular values i n parentheses have
`been recalculated with an I B M 650 computer f o r
`t h e u n i t c a l l dimensions a t atomic parameters
`of Kindsey and Barnes (1955).
`
`The interatomic d i s t a n c e s and angles suggestive
`of hydrogen bonding a r e l i s t e d i n Table 3.
`
`Inateratomic d i s t a n c e s and angles involving p o s s i b l e
`hydrgen bonds (. . .)
`2.772 A
`2.762
`2.852
`
`11
`
`H 2 0 ' ... H-Br
`H-Br...H-0
`H-BY. . .H-0"-H
`.H20'. . .OH
`O1..
`01...H20'...HBr
`OH... H20' ... HBr
`
`3.262 A
`3.395
`3.397
`
`112.9'
`102.5
`137.8
`353.2'
`
`H 2 0 ' . . . H B r . .
`.H20"
`H20' . . .HBr . . .H20"
`H20". . . H B r . . . H20"
`
`176.6'
`100.4
`82.3 -~
`359.3O
`
`Table 3 .
`
`0-H.. .N
`H-O'-H...O-H
`
`H-oI-H..
`
`. O1
`OH ... N-C16
`OH. . .N-C
`9
`OH ... N-CH3
`(C 16 -N-C9
`( c
`- N - C H ~ I I
`1 6
`(C~-N-CH
`3
`
`105.6'
`109.3
`104.1
`
`113.6)
`110.4)
`113.1)
`Mean 109.3'
`
`H20'. . .OH. . .N
`H20' . . . OH-C6
`
`C6-OH..
`
`.N
`
`105.5'
`122.3
`127.8
`
`Merck Exhibit 2188, Page 8
`Mylan Pharmaceuticals Inc. v. Merck Sharp & Dohme Corp.
`IPR2020-00040
`
`

`

`CODEINE PHOSPHATE
`
`101
`
`The system of p o s s i b l e hydrogen bond i s
`r e p r e s e n t e d by t h e broken l i n e s i n Fig. 2 .
`
`2.1.2.
`
`Melting P o i n t s
`
`Codeine phosphate m e l t s a t : -
`
`245 - 248O
`225 - 240'
`220 - 235'
`
`( 9 ) by h o t b a r method
`(9) by h o t s t a g e method
`w i t h dec. (10)
`
`2 . 1 . 3 .
`
`Eu tec t i c Tempra t u r e
`
`S a l
`D i c
`
`S a l
`Dic
`
`187'
`
`149'
`
`187'
`
`143O
`
`(9) by h o t bar method
`
`(9) by hot s t a g e method
`
`S a l = a c e t a m i n o s a l o l
`
`D i c = dicyandiamide
`
`2 . 2 . S o l u b i l i t y
`
`F r e e l y s o l u b l e i n water ( l g i n 4 m l ) ; v e r y
`s o l u b l e i n h o t water ( l g i n 0 . 5 ml); s l i g h t l y s o l u b l e
`i n a l c o h o l ( l g i n 4 5 0 ml) b u t more s o l u b l e i n
`b o i l i n g a l c o h o l ( l g i n 125 ml) (11, 1 2 )
`
`2.3. D i s s o c i a t i o n Constant
`
`The pKa v a l u e of codeine phosphate a t 20'
`8 . 2 ( 1 3 ) .
`
`i s
`
`2 . 4 . O p t i c a l R o t a t i o n
`
`D - 98'
`
`t o - 102'
`
`( 2 % aqueous s o l u t i o n ) ( 1 3 , 1 4 ) .
`
`The o p t i c a l r o t a t i o n of codeine phosphate as.013%
`aqueous s o l u t i o n and as .013 % e t h a n o l i c s o l u t i o n
`have been determined i n our l a b o r a t o r y u s i n g a Perk-
`i n E l m e r Polarmatic model 241 MC and found t o be:
`24'
`[ a ] D - 110'
`
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`102
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`F i g . 2 . P r o j e c t i o n showing p o s s i b l e h y d r o g e n b o n d s
`( b r o k e n l i n e s ) .
`
`Merck Exhibit 2188, Page 10
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`103
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`2.5.
`
`S p e c t r a l P r o p e r t i e s
`
`2.5.1 U 1 traviol e t Spectrum
`
`The UV spectrum of codein phosphate i n
`water w a s scanned from 200 t o 400 nm using
`Varian c a r r y 119 spectrophotometer.
`I t
`e x h i b i t s a c h a r a c t e r i s t i c UV spectrum
`(Fig. 3) with a maximum a t 284.8 nm (1570).
`
`Other UV s p e c t r a l d a t a of codeine phos-
`phate have a l s o been reported:-
`
`X max 284 nm
`
`(1585)
`
`i n water (15)
`
`A max 284 nm
`water. (16).
`
`(El%, 1 cm about 52.3)
`
`i n
`
`2.5.2
`
`I n f r a Red Spectrum
`
`The I R spectrum of codeine phosphate as
`KBr-disc was recorded on a Unicum SP 1025
`spectrometer (Fig. 4 ) . The s t r u c t u r a l
`assignments have been c o r r e l a t e d with t h e
`following hand frequencies i n Table 4 .
`
`Table 4.
`
`I R c h a r a c t e r i s t i c s of codeine
`phosphate
`-1
`Frequency Cm
`
`Assignment
`
`3500
`2500
`1645
`1618, 1515
`1280, 1090
`790,
`760
`
`-OH (broad)
`+
`-N H
`(alkene)
`C7=C8
`C=C (aromatic)
`c-0-c
`Two adjacent
`H (aromatic)
`Other c h a r a c t e r i s t i c absorption bands are:
`2990, 1460, 1335, 960 880 and 845 Cm-l.
`
`Merck Exhibit 2188, Page 11
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`IPR2020-00040
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`

`F i g . 3 .
`
`T h e UV spectrum o f c o d e i n e p h o s p h a t e in w a t e r .
`
`Merck Exhibit 2188, Page 12
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`

`8
`aD
`
`0
`
`0 0 -
`
`8
`N
`
`f
`
`a
`D
`
`3
`0
`
`>
`3
`
`-
`9) >
`P
`
`m
`c
`
`a!
`
`m c
`a
`m
`0
`J=
`a
`a,
`C
`.4
`a,
`73
`
`al u
`
`
`
`U
`
`u.4
`
`0
`E
`
`L. Y
`
`
`
`U a
`P
`K
`e:
`c
`
`Merck Exhibit 2188, Page 13
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`

`

`106
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`2.5.3 Nuclear Magnetic Resonance Spectra
`
`2.5.3.1
`
`Proton Spectrum
`
`The PMR spectrum of codeine
`phosphate i n deuterium oxide w a s
`recorded on a v a r i a n XL 200,
`200 MHz N M R spectrometer using
`tetramethyl s i l a n e a s a r e f e r e n c e
`standard (Fig. 5). The following
`s t r u c t u r e assignments have been
`made (Table 5 ) .
`
`Table 5.
`
`PMR c h a r a c t e r i s t i c s of codeine
`phosphate.
`
`Chemical S h i f t (6 )
`
`Assignment
`
`6.78
`6.95
`5.78
`5.40
`4.40
`3.87
`3.00
`
`(d)
`(d)
`(d)
`(m)
`(m)
`(s)
`(s)
`
`1 H
`2H
`7H
`8H
`9H
`3-OCH3
`N -CH3
`
`s = s i n g l e t , d = doublet, m = m u l t i p l e t .
`
`2.5.3.2
`
`C-NMR
`
`completely d ec oupl ed
`3C-NMR
`and off resonance s p e c t r a are
`shown i n Fig. 6.
`(A & B respec-
`t i v e l y ) . Both were recorded over
`5000 Hz range, i n deuterium oxide
`(conc. 575 mg/2 m l D20) on FT-80
`A-80 MHz NMR spectrometer. Using
`10 mm sample tube and tetramethyl-
`s i l a n e a s r e f e r e n c e standard,
`a t ambient.
`
`The carbon chemical s h i f t
`are assigned on t h e b a s i s of t h e
`
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`c
`a
`m
`0 s
`a
`aJ
`e
`.ri
`
`a; 4J m
`
`E
`3
`
`u
`a
`
`M
`.ri
`Lr,
`
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`CODEINE PHOSPHATE
`
`109
`
`a d d i t i v i t y p r i n c i p a l s and o f f reso-
`nance s p l i t t i n g p a t t e r n (Table 6 ) .
`
`l 7
`.cn3
`
`Table 6: Carbon chemical s h i f t s
`of codeine phosphate.
`Carbon No.
`Chemical S h i f t
`Carbon No.
`Chemical S h i f t
`PPm -
`ppm.
`33.4
`121.1
`c-1
`d
`c-10
`t
`125.0
`c-11
`c-2
`s
`d
`115.1
`129.9
`C-12
`142.7
`c-3
`s
`s
`42.4
`147.2
`s
`C-13
`s
`c-4
`c- 5
`41.90
`C-14
`66.7
`s
`d
`c-15
`21.8
`91.6
`C- 6
`d
`t
`C-16
`47.9
`c-7
`126.4
`d
`t
`C-17
`39.2
`134.1
`d
`C-8
`q
`57.2
`61.3
`c-9
`C-18
`d
`q
`s = s i n g l e t ; d = d o u b l e t ,
`t = t r i p l e t , q = q u a r t e t .
`Carbons 3 , 4 , 11, 1 2 and 1 3 chemi-
`c a l s h i f t s were a s s i g n e d , based on
`r e l a x a t i o n d a t a of t h e q u a t e r n a r y
`carbons ( 1 7 ) .
`
`2.5.4 Mass Spectrum
`
`The mass spectrum of codeine phos-
`phate o b t a i n e d by e l e c t r o n impact i o n i z a -
`t i o n which w a s recorded on Ribermag R-10-
`10 mass spectrometer eqquibed w i t h
`
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`110
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`d i r e c t i n l e t probe. The spectrum (Fig. 7)
`shows a molecular ion peak M+ a t m / e 299
`with a r e l a t i v e i n t e n s i t y 100%.
`
`The most prominent fragments and
`t h e i r r e l a t i v e i n t e n s i t i e s a r e l i s t e d i n
`Table 7.
`
`Table 7: Mass fragments of codeine phos-
`phate.
`
`- m / e
`
`R e l a t i v e I n t e n s i t y %
`
`299
`298
`229
`214
`188
`162
`124
`115
`81
`70
`59
`
`(base peak)
`
`100
`15
`20
`10
`10
`35
`20
`15
`10
`10
`15
`
`3 .
`
`Preparation
`
`3.1.
`
`I s o l a t i o n of Codeine
`
`Codeine occurs i n opium which i s t h e d r i e d
`l a t e x obtained from t h e unripe capsules of Papaver
`(Family Papaveraceae) . Opium
`somnif erum Linn.
`c o n t a i n s about 2% of codeine.
`
`Several methods have been used f o r t h e i s o l a -
`t i o n of codeine from opium. One of t h e s e i s a s
`follows :
`
`Powdered opium is e x t r a c t e d with w a r m water t o
`complete exhaustion. The e x t r a c t i s concentrated
`under vacuum, t r e a t e d with a s o l u t i o n of calcium
`c h l o r i d e (1 : l ) , l e f t f o r 48 hours and then f i l -
`t e r e d . The f i l t r a t e containing t h e hydrochlorides
`of t h e a l k a l o i d s i s concentrated when morphine and
`codeine hydrochlorides d e p o s i t i n t h e form of double
`compound known as "Gregory salt''. This salt i s
`dissolved i n warm water and n e u t r a l i z e d with d i l u t e
`
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`50 60 70 80 90 100 110 120 130 140 150 160 170 18C
`
`190 200 210 220 230 240 250 260 270 280 290 300 310
`
`F i g . 7 . The mass spectrum of c o d e i n e phosphate.
`
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`112
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`ammonia t o phenophthalein end point (pH 9 ) . Mor-
`phine p r e c i p i t a t e s , while codeine remains i n
`s o l u t i o n as ammonium-codeine c h l o r i d e . The s o l u t i o n
`i s concentrated, t r e a t e d with 30% sodium hydroxide
`and codeine is then extracted with chloroform.
`
`For f u r t h e r p u r i f i c a t i o n of codeine, t h e chlo-
`roformic l a y e r i s extracted with d i l u t e s u l f u r i c
`acid and t h e aqueous l a y e r i s decolorized with
`charcoal and f i l t e r e d . The f i l t r a t e i s rendered
`a l k a l i n e with sodium hydroxide s o l u t i o n and
`extracted with benzene, which i s evaporated t o
`dryness t o a f f o r d codeine.
`
`3.2.
`
`Formation of Codeine Phosphate:
`
`This i s formed by n e u t r a l i z i n g codeine with
`phosphoric acid and p r e c i p i t a t i n g t h e s a l t from
`aqueous s o l u t i o n with alcohol (18).
`
`4 . Synthesis of Codeine Phosphate
`
`The f i r s t s y n t h e s i s of t h e skeleton of t h e morphine
`a l k a l o i d s was achieved by Grewe e t a1 (19), whose method
`was i n fact a version of t h e biogenetic approach and invol-
`ved an acid catalysed c y c l i z a t i o n of benzylhexahydroiso-
`quinoline t o a morphine d e r i v a t i v e .
`
`4 . 1 Total Synthesis of Codeine (Scheme 1)
`
`The f i r s t t o t a l s y n t h e s i s of codeine was achieved i n
`1952 by Gates and Tschudi (2). The key intermediate
`"4-cyanomethyl-1,2-naphthoquinone" [8] was r e a c t e d with
`butadiene (Diels-Alder reaction) t o give [91 which when
`reduced with copper chromite underwent r i n g c l o s u r e t o
`t h e ketolactam [lo]. Reduction of [lo] (Wolf-Kischner
`method) gave [ll] which was N-methylated t o [I21 and
`reduced t o (t) -B-A6-dihydrodesoxy codeine [13] . Reso-
`l u t i o n was e f f e c t e d with d i b e n z o y l t a r t a r i c acid t o
`give t h e (+)-base. The resolved (+)-base was hydrated
`with d i l u t e s u l f u r i c acid t o [14], followed by p a r t i c a l
`demethylation and oxidation t o [15]. This was bromina-
`t e d t o [16] and isomerized t o t h e more s t a b l e l-bromo-
`thebainone [17]. Reduction of [17] gave dihydrothe-
`bainone [18]. F i n a l l y , [18] was brominated and t r e a t e d
`with 2,4-dinitrophenylhydrazine when oxide r i n g closure
`occured t o give t h e hydrazone [191, which upon heating
`with pyridine and s p l i t t i n g with a c i d gave l-bromo-
`
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`CODEINE PHOSPHATE
`
`113
`
`codeinone [20]. Reductive removal of 1-bromo gave
`codeine [21].
`
`A rather different approach was adopted by Elad and
`Ginsberg (20) who synthesized (-)-dihydrothebainone.
`This constitutes a formal total synthesis of codeine
`since (-)-dihydrothebainone is transformed into codeine
`by Gates and Tschudi (2).
`
`4.2 Partial Synthesis of Codeine
`
`Codeine can be prepared by partial synthesis from
`morphine.
`
`Morphine is dissolved in theoretical amount of
`potassium hydroxide dissolved in absolute alcohol, the
`required quantity of the methylating agent (usually
`phenyltrimethylammonium hydroxide) added, and the
`solution is heated at about 130". After cooling, water
`is added, the solution is acidified with sulfuric acid,
`the dimethylanilline formed is separated, and the
`alcohol is removed by distillation. Treatment with
`caustic soda solution precipitates the codeine, while
`any unreacted morphine is held in solution by the
`sodium hydroxide. The crude codeine is purified by
`crystallization as the sulfate (21).
`
`HO
`
`HO
`
`Methylation
`
`HO
`
`Morphine
`
`Codeine
`
`Codeine is also prepared from thebaine by appropri-
`ate reduction and demethylation
`(22).
`
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`114
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`Scheme 1: Total Synthesis of Codeine.
`
`”% O.C.Ph
`0 - FeC13
`~11%
`
`‘0-C.
`
`1. 1 so2
`
`[41
`
`0
`
`‘ 0 . C. Ph
`II
`0
`
`[31
`
`Ph
`
`:
`
`1. OK
`
`0
`[51
`
`Me% [81-I:;p
`
`M e
`
`OK
`
`CN
`
`HCOOEt
`CN
`
`[71
`
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`CODEINE PHOSPHATE
`
`115
`
`Me0
`
`Butad iene MeO/&
`
`Chr omit e
`CO;:;:
`
`Me0
`
`NaH/MeI
`
`L iA1H4
`
`1
`
`-11
`
`Me 0
`
`HO
`
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`116
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`KOHIdiethylene-
`glycol.
`Oppenauer oxi-
`d a t i o n i
`
`(3 ) CH3C0
`CH3 /H+
`
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`CODEINE PHOSPHATE
`
`117
`
`5. B i o s y n t h e s i s of Codeine
`
`P o s t u l a t i o n of t h e b i o s y n t h e t i c pathway o f opium
`a l k a l o i d s s t a r t e d i n 1910 w i t h t h e s u g g e s t i o n o f
`W i n t e r s t e i n and Trier (23) t h a t t h e b e n z y l i s o q u i n o l i n e
`a l k a l o i d s were b u i l t up i n n a t u r e from two u n i t s of 3,4-
`These molecules, w i l l
`dihydroxyphenylalanine (DOPA).
`g i v e rise t o 3,4-dihydroxyphenylethylamine and 3,4-dihyd-
`roxyphenylacetaldehyde by under going decarboxylation and
`o x i d a t i v e deaminat i o n r e s p e c t i v e l y .
`
`Gulland and Robinson (1) proposed t h a t morphine
`arises i n t h e p l a n t from a s u i t a b l e b e n z y l i s o q u i n o l i n e
`p r e c u r s o r (norlaudnosoline) by r o t a t i o n o f t h i s p r e c u r s o r
`followed by o x i d a t i v e r i n g c l o s u r e .
`
`The v a l i d i t y of such schemes remained u n t e s t e d
`u n t i l t h e advent of radiochemical t e c h n i q u e s , when i n
`1958 - 1960 experiments w i t h l a b e l l e d t y r o s i n e adminis-
`t e r e d t o poppy c a p s u l e s demonstrated t h a t t h e biosyn-
`t h e t i c r o u t e s proposed above do i n f a c t t a k e p l a c e i n
`l i v i n g p l a n t s .
`
`i n 1958 and 1961 (24, 25)
`B a t t e r s b y and Co-workers
`and Leete (26) e s t a b l i s h e d t h a t when
`2-I4C
`t y r o s i n e was
`fed t o poppy p l a n t , r a d i o a c t i v e t h e b a i n e , codeine and
`morphine w e r e obtained. These a l k a l o i d s were shown t o b e
`l a b e l l e d e q u a l l y and s p e c i f i c a l l y a t carbons 9 and 16 a s
`By f e e d i n g l-14C dopamine, B a t t e r s b y and
`expected.
`(27) found t h a t o n l y C-16 of t h e a l k a l o i d s w a s
`F r a n c i s
`Furthermore, B a t t e r s b y e t a1 (28)
`l a b e l l e d but n o t C-9.
`l-14C norlaudanosoline w a s incorporated
`have shown t h a t
`i n t o morphine molecule by p l a n t w i t h l a b e l l i n g a t C-9 only.
`
`These r e s u l t s i n d i c a t e d t h a t t h e phenanthrene a l k a -
`l o i d s were l a b e l l e d a t t h e a n t i c i p a t e d s i t e s .
`
`B a t t e r s b y e t a 1 (29) have f u r t h e r found t h a t (-)-
`r e t i c u l i n e i s t h e most e f f i c i e n t p r e c u r s o r t o morphine
`s k e l e t o n , and t h i s a l k a l o i d w a s found t o be p r e s e n t i n
`opium (30). Barton e t a1 (31) e s t a b l i s h e d t h a t s a l u t a r i -
`d i n e which do e x i s t i n trace amounts i n opium, is formed
`by phenolic o x i d a t i v e coupling of ( - ) - r e t i c d i n e .
`The
`e x i s t e n c e of codeinone as a n i n t e r m e d i a t e between t h e b a i n e
`and codeine w a s confirmed ( 3 2 ) .
`It w a s suggested by
`Barton and Cohen (33) and Bentley and Cardwell (8) t h a t
`t h e b a i n e is formed f i r s t i n t h e p l a n t and t h a t codeine,
`then morphine a r i s e d from it. Rapaport (34, 35) h a s shown
`
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`118
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`Scheme 2: Biosynthesis of Codeine
`
`Shikimic acid Pathway
`
`O J
`II
`CH2-C-COOH
`
`NH2
`I
`CH2-CH-COOH
`
`p-hydroxy phenyl pyruvic
`
`OH
`
`Q - c____, 0 OH
`Tyros ine 1 NH2
`acid i:
`HO 0 OH -0 OH
`
`CH2-C-COOH
`
`I
`
`CH2-CH-COOH
`
`HO
`
`3,4-dihydroxy phenyl pyruvic
`acid
`
`DOPA
`(3,4-dihydroxy phenylalanine)
`
`HO
`
`H
`H
`
`HO
`
`HO
`Norlaudanosoline carboxylic
`acid
`
`3,4-dihydroxy phenylethyl-
`amine.
`
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`

`CODEINE PHOSPHATE
`
`119
`
`H -9 HO H F!$
`
`NH
`
`OH
`Nor laudanoso-
`l i n e .
`
`HO
`
`Norlaudanosoline
`
`HQCO
`
`H3C0 "
`
`$ N t
`
`
`
`HH:$!32NcH3
`
`0
`(+) S a l u t a r i d i n e
`
`OH
`( - ) Reticuline
`
`5
`
`Thebaine
`
`Codeinone
`
`Codeine
`
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`

`1%
`
`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`by exposing Papaver somniferum p l a n t s t o 14c02 f o r vary-
`i n g l e n g t h of time, t h a t r a d i o a c t i v e t h e b a i n e was f i r s t
`formed i n t h e p l a n t and was converted i n t o r a d i o a c t i v e
`codeine and t h i s w a s converted i n t o r a d i o a c t i v e morphine
`b u t n o t i n t o thebaine. B a t t e r s b y (36) h a s independently
`reached t h e same conclusion.
`
`The b i o s y n t h e s i s of codeine is i l l u s t r a t e d i n
`scheme 2.
`
`6. Metabolism
`
`The a b s o r p t i o n of codeine i s r e l a t i v e l y r a p i d a f t e r
`p a r e n t e r a l a d m i n i s t r a t i o n and e r r a t i c a f t e r o r a l medica-
`t i o n (37). Codeine i s metabolised mainly i n t h e l i v e r .
`The predominent m e t a b o l i c changes are N-demethylation
`t o
`norcodeine, 0-demethylation
`t o morphine and c o n j u g a t i o n
`w i t h g l u c u r o n i c a c i d a t t h e 6-hydroxyl t o 6-0-glucuronide.
`
`Experiments w i t h e i t h e r 0-methyl o r N-methyl 14C-
`l a b e l l e d codeine have shown t h a t r a p i d d i s p o s a l o c c u r s
`i n man and t h a t 24 hours a f t e r i n j e c t i o n , t h e maxium of
`morphine (4-13%) , norcodeine (8%) , bound codeine (35 -
`40%) and unchanged codeine ( 5 - 12%) i s p r e s e n t i n t h e
`u r i n e ; n e g l i g i b l e amounts are found i n t h e f e c e s and
`o n l y p a r t of t h e detached 0-methyl and N-methyl r a d i c a l s
`can be recovered a s expired carbon d i o x i d e (38, 39).
`
`I n 24 hours following o r a l a d m i n i s t r a t i o n of 4 mg/Kg
`i n d i v i d e d doses, 4% of t h e dose was excreted i n t h e
`u r i n e as f r e e norcodeine, 14% as conjugated norcodeine,
`1% as f r e e morphine and 7% as conjugated morphine (16).
`
`The metabolism of codeine is presented in"scheme 3 .
`
`7. Methods of Analysis
`
`7.1
`
`I d e n t i f i c a t i o n Tests
`
`The following i d e n t i f i c a t i o n t e s t s a r e t h o s e
`mentioned i n t h e U.S.P.XX(11):-
`
`A) The i n f r a r e d a b s o r p t i o n spectrum of a potassium
`bromide d i s p e r s i o n of it , p r e v i o u s l y d r i e d ,
`e x h i b i t s maxima o n l y a t t h e same wavelengths as
`t h a t of a s i m i l a r p r e p a r a t i o n of USP Codeine
`Phosphate Reference Standard.
`
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`

`CODEINE PHOSPHATE
`
`121
`
`Scheme 3 : Metabolism o f Codeine.
`
`H
`
`I
`
`0 GCH3
`
`/
`
`CH3
`
`42 \
`
`Morphine
`
`I m OH
`'b "', H
`
`I
`
`OH
`
`'"'
`
`OH
`
`Normorphine
`
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`FARID J. MUHTADI AND MAHMOUD M. A. HASSAN
`
`i n 15 m l of water. Render t h e
`Dissolve 100 mg
`s o l u t i o n a l k a l i n e with ammonia TS, e x t r a c t witli
`t h r e e 5-ml p o r t i o n s of chloroform, f i l t e r t h e
`combined chloroform e x t r a c t s through f i l t e r
`paper t h a t previously has been washed and mois-
`tened with chloroform, and evaporate t h e com-
`bined chloroform e x t r a c t s on a steam bath j u s t
`t o t h e disappearance of t h e chloroform odor:
`t h e r e s i d u e of codeine m e l t s between 154' and
`158'.
`
`To 1 mg contained i n a porcelain c r u c i b l e o r
`small d i s h add 1 drop of s u l f u r i c a c i d contain-
`ing, i n each m l , 5 mg of selenious acid: a
`green c o l o r i s produced a t once, and i t r a p i d l y
`changes t o blue, then slowly t o dark o l i v e -
`green.
`
`To a s o l u t i o n of 5 mg
`i n 5 m l of s u l f u r i c acid
`contained i n a test tube add 1 drop of f e r r i c
`c h l o r i d e TS, mix, and heat i n b o i l i n g water f o r
`2 minutes: a blue color i s producted and upon
`t h e a d d i t i o n of 1 drop of n i t r i c acid changes
`t o red-brown.
`
`Neutralize a s o l u t i o n (1 i n 50) with ammonia
`TS, and add s i l v e r n i t r a t e TS: a yellow preci-
`p i t a t e of s i l v e r phosphate i s formed, and i t
`i s s o l u b l e i n d i l u t e d n i t r i c a c i d and i n
`ammonia TS.
`
`Other i d e n t i f i c a t i o n tests (16, 40) are as
`follows :
`
`Place a l i t t l e i n powder, on t h e s u r f a c e of
`a drop of n i t r i c a c i d , a yellow color i s produced.
`
`Add t o a l i t t l e of codeine, 1 m l of s u l f u r i c
`a c i d containing drops of formaldehyde, a purple
`color is formed ( s e n s i t i v i t y 0.05 u g ) .
`
`Add drops of ammonium molibdate t o codeine
`phosphate, a green c o l o r i s produced ( s e n s i t i v i t y
`0.1 u s ) .
`
`7 . 2 Microcrystal Tests
`
`Add potassium cadmium iodide s o l u t i o n t o codeine
`
`Merck Exhibit 2188, Page 30
`Mylan Pharmaceuticals Inc. v. Merck Sharp & Dohme Corp.
`IPR2020-00040
`
`

`

`CODEINE PHOSPHATE
`
`123
`
`phosphate, g e l a t i n o u s r o s e t t e s c r y s t a l s a r e formed,
`changing t o aggregates of s m a l l t a b l e t s (16).
`
`Add potassium t r i - i o d i d e s o l u t i o n t o codeine,
`f e a t h e r y r o s e t t e s c r y s t a l s formed overnight (16).
`
`7.3 T i t r i m e t r i c Methods
`
`The o f f i c i a l methods of determining codeine
`phosphate are described by t h e B.P.
`(40) and
`U.S.P.XX(11).
`
`