1456
`
`
`
`
`
`Phenoxymethy!Penicifin(Units/ml)
`
`CHAPTER 76
`
`If the clinical impression of the drug being
`units (90%).
`evaluated was that a 20% difference in dose (plasma levels}
`would noibeclinically significant, in this example it must be
`concluded that the statistical test is too sensitive and the
`difference observed, evenif real, is not significant clinically.
`Therefore, the drug products are bioequivalent in spite of
`the statistical findings.
`Statistics should be used, in bioavailability testing, as a
`tool to determineif sufficient subjects have beenincluded to
`minimize the effect of patient-to-patient variability in the
`data analysis. The results ofstatistical testing should not
`be used as the decision but to help make the decision. One
`must apply somestatistical sense in orderto avoid statistical
`nonsense.
`A Common Pitfall: Cross-Study Comparisons—Per-
`haps the single most-common error made in interpreting
`bioavailability datais that of cross-study comparison, This
`occurs when the blood coneentration-time curve of a drug
`product in one study is compared with the blood concentra-
`tion-time curve of that drug product in another study.
`‘There are three reasons why such cross-study comparisons
`are dangerous and can jead to false conclusions.
`‘The follow-
`ing examples used to illustrate the three points are taken
`from actual bioavailability data.
`Different Subject Population—In Fig 76-9, a research lot
`of potassium phenoxymethy! penicillin was compared with
`the appropriate reference standard for that product. The
`research-lot drug was found to be bioequivalent, with aver-
`age peak-serum concentrations differing by 8% and the area
`differing by only 9%.
`‘n another study conducted with a
`full-manufacture lot of the test product, the same lot of the
`reference standard potassium phenoxymethylpenicillin was
`used. The resulis of this study are shown in Fig 76-10.
`Again, the two products were found to be higequivalent as
`the peak and area parameters differed by less than 5%.
`In
`these twostudies, identical test conditions were used and the
`same analytical procedure and laboratory was employed.
`However, if one compares the serum levels for the reference
`standard lot found in Fig 76-9, with the levels for the same
`lot of tablets in the study in Fig 76-10, sizable differencesin
`blood levels are found as shown in Fig 76-11.
`The average peak serum levels for this lot of tablets were
`found to he 8.5 units/mL and 12.5 units/ml in the two
`respective studies, # difference of approximately 31%. Like-
`wise, the average AUC was found to differ by approximately
`21%. Such differences are the sole result of cross-study
`
`
`
`
`
`PhenoxymethylPenicillin{Units/mL)
`
`8=
`
`oe>
`
`e
`
`4
`\1
`
`@ Ona 600 mg Tablet Phanoxymathyl Poniciflin
`Lot 416.674
`& One 600 mg Tablet Recognized Standard
`Lot f4VN13B
`
`mn o
`
`Time thours)
`
`Fig 76-10. Average serum concentration of phenoxymethy! penicil-
`lin following oral administration of 5600 mg given as one tablet of
`Recognized Standard (A}, or of Test Product, Full Mfg Lot (mB),
`
`
`
`
`
`PhenoxymethytPenicillin(Units:mL)
`
`* 2
`
`20
`
`@ Study 1
`
`© Study 2
`
`WG)
`
`
` tk NK TO 3 6
`
`
`Time (hours)
`
`Fig 76-11, Averags serum concentration of phenoxymethyt penicll-
`lin following a single oral 500-mg dose of Recognized Standard, in
`{wo different subject populations.
`
`comparisons and are not due to differences in actual bio-
`availability.
`The same lot of reference standard tablets was used in
`both studies. Hence, the difference must be due to the
`experimental variables which occur normally from study to
`study. The major difference between the two studies was
`the subject population involved.
`In the first study, healthy,
`adult, male, prison volunteers were used, whereas in the
`second study, there were 17 females and 7 males in a hospital
`clinic, also described as normal, healthy volunteers. An
`appreciable difference in sex distribution was obvious when
`comparing these studies. Adjustinents for body weight and
`surface area alone did not correct for the apparent discrep-
`ancies in peak concentrationor blood level AUC.
`It is diffi-
`cult to determine the exact factors which caused the ob-
`served differences.
`‘Chis example should serve as a note of
`caution in comparing absolute bioavailability values of peak
`concentration and area underthe curve from different stud-
`ies.
`
`Different Study Conditions--Parameters such as the
`food or fluid intake of the subject before, during and after
`drug administration can have dramatic effects on the ab-
`sorption of certain drugs. Fig 76-12 shows the results of a
`three-way crossover test where the subjects were fasted 12 br
`overnight and 2 br after drug administration of an uncoated
`
`9 One 600 mg Tablet Phanoxymethyl Penicillin
`Loe #16,674-1
`4 One 600 mg Tablet Recognized Standard
`
`a
`f
`
`9.0
`
`3.0
`
`Lot #4VN138 6.0
`
`Time (sours)
`
`Fig 76-9. Average serum concentration of phanoxymetiyt peniciliin
`foilowing oral administration of 500 mg given as one tablet of Recog-
`nized Standard {A}, or of Test Product, Research Lot (Q).
`
` PFIZER, INC. v. NOVO NORDISK A/S - IPR2020-01252, Ex. 1013, p. 301 of 408
`
`

`

`
`
`BIQAVAILABILITY AND BIOEQUIVALENCY TESTING
`©.
`Hy tO,
`Hi
`a,
`4
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`je Sey Ss
`4
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`wah}
`NO
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`74
`
`Fig 76-15. Average plasma prednisolone levels following 60 mg of
`prednisono adininistered to 24 normal adults as a single oral doso of
`twelve 5-mg prednisone tablets from two different manufacturers.
`Plasma levols were determined by a competitive protein-binding
`assay.
`
`also suggestthat neitherfilm-coating nor enteric-coatingis
`necessary for optimal blood-level performance. }igure 76-
`13 shows results with Lhe same tablets whenthe study condi-
`tions were changed to only a 2-hr preadministration [ast
`with a 2-hr postadministration fast.
`In this case, the blood
`levels of the uncoatedtablet were depressed markedly while
`the film-coated andenteric-coated tablets showedrelatively
`litle difference in bloodlevels.
`From this second study, it might be concluded that film-
`coating appears to impart the same degreeofacid stability as
`an enteric coating.
`‘This might be acceptable if only one
`dose of the antibiotic was required. However, Fig 76-14
`shows the results of a multiple-dose study in which the
`enteric-coatedtablet andthe film-coated tablet were admin-
`istered 4 times a day, ¢mmediately after meals. The results
`show thatthe film coating does not impart the degree of acid
`stability as does the enteric coating when the tablets are
`administered immediately alter food in a typical clinical
`situation.
`Different Assay Methodology---Depending on the drug
`under study, there may be more than one assay method
`available. Jor example, some steroids can be assayed by a
`radioimmunoassay, competitive protein-binding, gas-liquid
`
`Qo
`
`& Two 260 ing Enythromysin fablorg
`No Film of Eatoric Coating Aes. #16.263-)
`6 Teo 250 ng Erytheomyecin Tablets
`Filey Coatod Ros. #46,260-2
`
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`Twe 260 mg Erythromycin Tattats
`Entozie Caatod Nos. #16,208-3
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`
`Fig 76-42. Average sorum erythromycin concentrafion adminis-
`tered in 500-mg doses as three different tablet dasage forms. The
`results ware cbtained from 21 healthy adult subjects following an
`overnight fast of 12 hr before and 2 hrafter drug acministration.
`
`20 E
`
`© Two 250 my Enytiiramycin Tatdots
`No Filtn at Estoric Coating Ros £16.209-3
`6 Two 200 my Erythromycin Tablots
`Film Costod Nos #16.268-2
`
`
`
`@ Two 260 my Erythromycin Tablots
`Enteric Contod Ros #16,268-3
`
`Time thourst
`
`3 Sh
`E
`z4
`93
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`£2g =w
`
`e
`
`Fig 76-13. Average serum erythromycin concentration adminis-
`tered in 500-mg doses as three different tablet dosage forms. The
`results wore obtained from 12 healthy adult subjects with only a 2-hr
`fast before drug administration.
`
`tablet, a film-coated tablet or an enteric-coated tablet of
`erythromycin.
`The results of this study suggest that the unprotected
`tablet is superior to both the [iim-coated and enteric-coated
`tablets in terms of blood-level performance.
`'These results
`
`
`
`1457
`
` a
`
`BW One 250 mg Erythromycin-
`@ One 250 mg Erythromycin -
`
`Enteric Coated Lot #082.FM
`Film Coated Lot #70-716-AF
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`Fig 76-14, Average serum erythromycin concentration-time profiles administered in two different tabiet dosage forms. The results were
`obtained from 24 healthy adult subjects following administration of 250 my 4 times a day, with meais and at bedtime.
`
` PFIZER, INC. v. NOVO NORDISK A/S - IPR2020-01252, Ex. 1013, p. 302 of 408
`
`

`

`GHAPTER 76
`
`100.6
`
`ao iNvoy
`
`
`
`(ug?100mL) Time hours?Prednisotone
`
` 1458
`
`~~
`
`aE
`
`ac
`
`88
`
`f
`& Twolve 5 otg Preadnisane Teblor No.
`# Twolve & mg Prednisone Tablet No %
`
`00.0
`
`bea
`
`400
`
`8 wo
`s2é
`z5
`&a
`
`
`
`708
`
` a
`
`4,
`\
`
`Oo
`
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`
`7 Ra
`
`4
`
`8
`
`Ywelve $ my Prednisone Tablot No 4
`Radoinmuncassay
`Twolve § mg Prodnigone Tablat No.
`® Competiuvo Pratein Binding Assay
`
`1
`
`~~renee
`
`erate,fywattnemererneanetnnatsntusesntitee
`Ta
`24
`Tinst {hours}
`
`Fig 76-16. Average plasma prednisolone ievels following 60 mg of
`prednisone administered to 24 normal adults as a single oral dose of
`12 5-mg prednisone tablets from two different manufacturers. Plas-
`ma levels were determined by a radioimmunoassay procedure.
`
`chromatographor, indirectly, by a 17-hydroxycorticosteroid
`assay.
`Figures 76-15 and 76-16 show the results of a comparison
`of prednisone tablets using a competitive protein-binding
`method and a radioimmunoassay, respectively. The seruin
`concentration-time curves resulting from each method lead
`to the same conclusion, that the products are bioequivalent.
`However, Fig 76-17 shows a comparisonof the absolute val-
`ues obtained by the two assay methods with the same prod-
`uct.
`Obviously, the wrong conclusion would have been reached
`if one product had been assayed by one method and the
`other product by the other method and theresults had been
`compared. Even in cases where only one assay method is
`employed, there are numerous modifications with respect to
`technique among laboratories which could makedirect com-
`parisons hazardaus.
`The backboneof any bioavailability study involving plas-
`ma(or urine) levels of drug, in addition to good study design
`and subject controls, is the analytical methodology used to
`determine the levels of a drug.
`In most cases one probably
`can assume that the precision and reliability of the method
`employed in a given study have been established to a suffi-
`cient degree to make the results of the study internally
`consistent. As demonstrated, major problems arise when,
`without careful evaluation of the analytical methodology
`employed, one attempts to compare the dataof studies from
`
`Fig 76-17. Average plasma prednisolone profiles administered as a
`single 60-mg dose to 24 normal adults. Plasma levels were deter-
`mined by both a competitive protein binding assay and a radioimmu-
`noassay.
`
`different laboratories. Even with similar analytical meth-
`odology performed by the same laboratory, it would be un-
`reasonable to expect agreement, using the same dosage form,
`of closer than 20 to 25% for plasma levels, AUCs, ete, froin
`one study to the next.
`Under the best conditions, cross-study comparisons are
`relatively insensitive, and at worst they can be misleading.
`Cross-study comparisons certainly cannot be used to make
`decisionsor estimations of differences in drug products with
`the generally acceptable sensitivity of difference detection
`of 20% orless.
`Withinsufficient data on the correlation of plasmalevels
`with clinical response,itis difficult to decideif it is the peak
`plasmalevel or the total body load of a drug that is impor-
`tant. Changes in the rate of absorption require changes in
`the dose given (body load) for maintenance of similar peak
`plasma levels. Decisions as to which is more important,
`body load or peak level, are made with difficulty and tend to
`reduce the objective quantitation sought in bioavailahility
`testing.
`
`Bibliography
`Chedos DJ, DiSanto AR: Basics af Beavatlability, The Upjohn Co,
`Kalamazoo, 19738.
`Dittert LW, DiSanto AR: J APhA NS13:(8): 000 1973.
`DiSanto AR et ats
`Int Clin Pharmacol 13: 220-227, 1976.
`
` PFIZER, INC. v. NOVO NORDISK A/S - IPR2020-01252, Ex. 1013, p. 303 of 408
`
`

`

`behdeansustanavsineferedeanmecoregbps
`etarnerreerLAAPRsypePeeUNUMALLUREeyHNPmrtneaannanane}Js
`
`
`a C
`
`HAPTER 79
`
` f
`
`|:
`|
`
`Tonicity, Osmoticity, Osmololity and
`Osmolarity
`
`Frederick P Hegel, PhD
`Protessor oF Phorrnceouiles
`College of Phounucy, Univernily of lines
`Chicage.Il 40612
`
`Tt yonerally is aceapled that osmotic ffects have a majar
`place in dhe maintenance of homeostasis (the state al’ epi
`librium in the living body with respect to varioua Funetions
`and to the chemical composition of the flaida and issues, a,
`temperature, heart rate, blood pressure, water contont or
`blood sugar).
`‘To a great extentthese offeets ceeur within ar
`between celle and tissues where (hey canned ho measured.
`Oneof the mout troublesome problems in clitdeal medicineis
`the maintenanceofadequate body fluids and proper halance
`between extracellular and intracellularfluid volumes in seri-
`oualy i patiania.
`Te should be kept in mind, however, “hat
`fluid and alectrelyte abnormalities are not diseases, but ave
`the manifestations of disease.
`‘The physiological mechanisms which contral water intake
`and ontput appaarto ragpond primarily to seram oamoticily,
`Renal regulation of matput is jafluenced by variation in rate
`of releaae of pituitary antidiuretic hormone (ADH) and oth-
`er factors in response lo changes in dorum osmotielty, Og.
`motic changes also serve aa a stimulus to moderate thirst,
`Thiy mechaniamnia sufficiently sensitive to iimit variations
`in ostnatidity fa the neynid individual to less than about 1%,
`Body fluid continually oscillates within Unie narrow range.
`Anincrease of plaama asmatielty of 1% will stinnulaie ADH
`release, reault in reduction of urine flow and, at the same
`time, stimulate Ghirat Ghat resulta oy inergased watar intalse,
`Both (he increased renal reabsorplion of water (without
`solute) simulated by cireulating ADH and the increased
`water intale: Lend to lower serum osmaticity,
`The dransforof water through the cell menibrane occurs ao
`rapidly that any lack of osmotic equilibrium between the two
`fluid compartments in any given tissue Usually is correctod
`within a few seconds and, al moad, within a minute or so,
`However, this rapid transfer of water does nol mean that
`complete equiliaration occurs holween dhe extracellular and
`intracellular campartinents throughout
`the entire body
`within this sama short period of time.
`‘The reasonis that
`
`fluid usually enters the body through the gut and then muat
`be tranaported by the cieculatory ayatem toall tissues before
`complete equilibration cat oceur,
`In the normal person it
`niay tequive 30 to G0 min te achieve reasonably good equili-
`bration throughout the body after drinking water. Osmati-
`city is the property that largely determines the physiclogle
`acceptability of a variety of solutions used for therapeutic
`and nutritional purposes,
`Pharmaceutienl and thornpeutic consideration of aamotic
`effects has been, lo a great extent, directed toward theside
`affects af ophthalmic and parenteral medicinals due to al-
`normal osmoticity, and te either formulating to avoid the
`side effects or finding methods of administration to mini-
`mize them. More recently this consideration has been ex-
`tended 40 total (central) parantaral nutrition, 4anteral hy-
`péralimentation (“tube” feeding) and to concentrated-Auid
`infank formulas.'! Alao, in recent years, (he importance of
`opmometry of serum and urine in the diagnosis of many
`pathological conditions has been recouniaeadl,
`
`Thereare a number ofexamples of the direct therapeulic
`affeet of osmotic action, such ag Wie intravencs use of man-
`nite) aaa diuretic whichia filtered at (he glomeruli and dius
`inereases the osmotic pressure of tubular uring. Water
`muat Uhen be reabsorbed againsi, a higher osmotic gradient
`than otherwise, ac reabsorption is alawer and diuresis iy
`observed.
`‘The same fundamental principle applics to the
`intravenous administration of 40%urea used10 affect intra-
`cranial pressure in the control af cerebral edema. Peritone-
`al dialysis fluide tend Go ba semewhat hyperosmotic to with-
`draw water and sitragonous metabolites. Two do five per-
`gent aodiuin chloride solutions or dispersiang in an
`oleaginons base (Mura, Bausch & Lomb) and a 40% ghucese
`oiniinent are used topically for corneal edema. Ophthalgan
`(Ayerst) is ophthalmic glycerin employed for its osmotic
`wffect. to clear edematous cornea to facilitate an ophthalme-
`seopie or gonioscopic exaniination. Glycerin agiutions in 0
`to 75% concentrations (Glyrol (O Lad), Osmoglyn (Alcon)]
`and fsosorbide solution [Ismotic (Alcon)] are oral osmotic
`agents for reducing intraocular pressure, The gamotie prin-
`ciple alag applies to plaama extenders such as polyvinylpyr-
`retidong and to saline laxatives such as magnesium sulfate,
`magnesiumcitrate salution, magnesium hydroxide (via gas-
`trie neutealization), sodium sulfate, soditun phosphate and
`aodium biphosphate oral solution and enerna (Fleet),
`Aninteresting datnotic laxative which is a nenelectrolyte
`is a lactulose solution. Lactulose is a nonabsorbable disac-
`charide which ia colon-apecific, wherein colonic bacteria de-
`grade aome of the disaccharide to lactic and other simple
`organic aeida. These, in Lolo, lead to an oumotic affect and
`lagation. An oxtension of this therapy is Hustrated by Ce-
`photic (Merrell-Dow) solution, which wes the acidification
`af the colon via lactilose degradation to serve aga trap for
`ammonia migrating from the hloed to the colon, The cun-
`version of smimonia of bload to the ammoniumion in the
`colon ultimately ia coupled with the osmotic effect and laxa-
`tion, thus expelling undesirable levels of blood ammonia.
`Thig produet is employed to prevent andtreat frontal ays-
`temic encephatopathy,
`Osmotic laxation is known with the gtal or rectal use of
`glycerin and sorbitel.
`Epsom aalt: haa been used in baths
`and compresses to reduce edema aagociated with sprains. A
`relatively new approach is Wie indirect application af the
`oamotic effect In therapy via osmotic pump drug delivery
`syatenia,?
`if a solution in placed in contact with a membrane Latis
`permeable to molecules of the solvent, but not ta molecules
`of the aohuite, tha movement of solvent through (he mem-
`brane is called osmosis, Such a mentbrane is often called
`semipermeable, As the several ypes of membranes of the
`body vary in their permeabilily, it is wall to nate that they
`are selectively permeable. Most normal living-gell mem
`brandy maintain various goluie concentration gradionts. A
`adlectively permeable memlrane may be defined aither as
`one that does not permit free, unhampercddiffusion of all
`1491
`
` PFIZER, INC. v. NOVO NORDISK A/S - IPR2020-01252, Ex. 1013, p. 304 of 408
`
`

`

` 14hz
`
`CHAPTER 79
`
`the solutes present, or as one that maintains at least one
`solute concentration gradient aerons ileolf Qsmosia, (han,
`js the diffusion of water through a membrane that maintains
`al east one solute concentration gradient across itself.
`Assume a Solution A on aneside of the membrane, and a
`Soludon B of the samesolute but of a higher concentration
`on the otherside; the solvent will Lend to pags inte the more
`coneentwated solution until equililrium has been extab-
`lished,
`‘The pressure required 4o prevent this mavemant. is
`the oamatic proasure,
`Itis defined as the excess pressure, oF
`pressure grentar than that above the pure solvent, whieh
`must be applied to Solution B to prevent passage of solvent
`through a perfect semipermeable membrane from A lo 13,
`The concentration of a solution with respect to affect on
`osmotic pressure is related ta the number of particles
`(unionized molecules, ions, macromolecules, agqregates) of
`aolute(s) in solution and thus is affected by the degree of
`ionivalion or appregation of (he solute. See Chapter 16 for
`review of colligative properties af solutions,
`Bodyfluida, including blood and lacrimal fluid, normally
`have an ostaoliae pressure which offen is deseribed ay garta-
`sponding to that of a 0.9%soludion of aediumchloride,
`‘The
`body algo aliempls to keep the oamotie pressure of the can-
`tenta of the gastrointestinal Gract al about this level, [ut
`there dhe normal range ig much wider than that of most body
`fluids,
`‘The 0.9% sodium chloride solution ia said to be
`iscosmotic with physiological
`fluids,
`‘Phe term Lseterre,
`meaning equal Lone,
`ia in medical usage commonly used
`interchangeably with ideoamotic. Mowever, derma such ag
`isotonic and Lonicity should be used grly with reference to a
`physiologic fluid.
`lseoamotie actualiy is a physical texm
`which compares thy osmotic pressure (or anathercalligative
`proporty, such as freazing-point depression) of two liquids,
`neither of which may be a physiological fluid, or which may
`be a physiological {uid only undercertain circumstances,
`Nor axample, a solution of borie acid that ig isooamotic with
`both blond andlacrimal fluid is isotonic only with the lacri-
`mal fluid. This solution causes hemolysis of red blood calls
`because molecules of boric acid pass freely through tha
`erythroeyie membrane regardless of concentration.
`‘Thus,
`jnoloniaity infers a sense of physiologic compatibility where
`jagoumoticity need not. As another example, a “chemically
`defined olemental diet” gr enteral nutritional fhad qin be
`jacoamotie with the contents of the gastrointestinal tract,
`butwould not he considered a physiological fluid, or suitable
`for parenteral uge.
`A solution is isotonic with a living call if there is no ned,
`gain orlows of water by the cell, or other change in thecell
`when if ig in contact with that solution. Physiologic solu-
`Lions with an oamotic pressure lower than that of bady fu-
`ids, or of 0.9% aodium chloride solution, are referred Lo
`commonly as being hypotonia, Physiolagden!] solutions hav-
`ing 4 wreater osmotic pressureare termed Ayipertantc,
`Such qualitative terms are of limited value, and it has
`become necossaryto stale osmotic properties in quantitative
`terms.
`‘To do ao, a torm must be used that will repreacnt. all
`the particles which may be present ina given system,
`‘The
`term used is osmol. An oamol is defined as lhe weight, in
`prams,ofa solute, cxfaling in a solution as molecules (and/or
`iong, macromolecules, aggregates, etc), which is osmotically
`equivalent to a mole of an ideally behaving nonalectrolyte.
`‘Thos, the camol-weightof a nonclectrolyte, in a dilute sok.
`tion, genernjly is equal ta ita yram-molecular-woight, A
`milliogmel, abbreviated mOsm, in Lhe weight stated in mill.
`grams,
`If one extrapolates this concept of relating an oxmol and a
`mole ol' a nonglectrolyte aa being equivalent, then one alse
`may define an oamol in the following ways. tis the amount
`of solute which will provice ona Avogadro's number (6.02 %
`10) of particles in solution and itis the amount of solute
`
`which, on dissolution in 1 ke of water, will result, in an
`osmolie prosaire increase of 22.4 almospheras.
`‘This is de:
`rived from the gas equation, PV = n1@T, assuming ideal
`candilions and standard temporature of O°. Mis is equiva:
`Jend (oan incronse of 17,000 torr or 19,300 torr at 87", One
`mOsimel
`ig one-thousandth of an ogmal. Tor oxample,
`1.
`mole of anhydrous dextrose ia equal ta 180. One Osrol of
`this nonelectrolyte is also 180g. Gne mOsmal wouldle 140
`pe.
`‘Thus 180 my of thisaalute dissolvedin 1 ly of waterwill
`produce an increase in osmotic pressure of 19.9 Lory at body
`Lempenitiire.
`For a salation of an electrolyte such as sodium chloride,
`one motecule of godiumchloride represents one sodium and
`ona chloride fon. Hence, one mole will represent2 osmols of
`sodium chloride theoretically. Accordingly, ] oamel NaCl =
`56.5 0/2 or 20.259, This quantity represents the sum total of
`6.0% *% 10% jong as the total number of particles,
`Ideal
`solutions infer very dilute solutions or
`infinite dilution.
`However, as the concentration is increased, other fachors
`
`enter. With strong eleetrolytos, interionic abtractian canuats
`a decreasein their effect on ealligative properties,
`In adei-
`téon, and in opposition, for all solutes, including nonelectsro-
`
`iytes, solvation and poxsibly othar factors operate to intensi-
`fy their colligative effect. Therefore, it is very difficult and
`often impossible to predict accurately the oamoticity of a
`solution.
`lmay be possible to dose for adilute solution ofa
`single, pure and well-characterized solute, but not for moat
`parenteral and onteral medicinal and/or autritonal fluids;
`experimental determination hkely is required.
`
`Osmolality and Osmolarity
`
`It is necessary to use several additional terms to define
`expressions of concentration in reflecting the osmoticity of
`solutions.
`‘The terma include ogmelality, ihe expression of
`osmotlal concentration and osmotarity, the expression of as-
`molar concentration,
`
`Osmolality
`solution has an osmolal concentration of
`one when if contains 7 oamol af solute/ty of water, A solu
`tion has an osmolality of n whenit comtaing 1 asmols/ke of
`water, Osmolal solutions, like their counterpart malal solu-
`tions, reflect a weight to weight relatiouship between Lhe
`solute and the solvent. All solutions with the same malol
`concentrations, irreapoctive of solute, contain Lhe aame mole
`fraction (fa) of alute.
`In water
` mole
`a
`mols sollte + moles solvent
`
`
`tr
`1.
`” 66.5
`
`thug, for a ane malal solution
`_Lmole solute
`L mole solute + 54,5 molos water per kg
`hy
`Since an camolof any nonelectrolyte is equivalent to 1 moka
`of that compound, than a f osmolal solution ta synonymous
`toa 1 molal solution for a typical nonelectrolyts
`With a typical electrolyte like sodiumchloride, 1 aamolis
`approximately 0.5 mole of aodiumchloride,
`‘Thus, ifollows
`that al osmolal solution of aodium chloride essentially is
`equivalent 10.0 0.5 molad aviuiion. Recall that a i oamalal
`solution of dextrose or sodium chloride each will contain the
`aame particle concentration.
`In the dextrose solution Lhare
`will he 6.02 *% 102" molecules/Iq of water and in he sodium
`chloride solution one will have 6.02 % 10") total ions/leg of
`water, one-half of which are Na"ions and the other half Cl"
`ions.
`‘The mote fraction, in terms of total particles, will be
`the samme and, hence, (he same oamotic pressure,
`Ag in molal solutions, oamolal solutions usually are em-
`ployed where quantitative precision is required, as in the
`
` PFIZER, INC. v. NOVO NORDISK A/S - IPR2020-01252, Ex. 1013, p. 305 of 408
`
`

`

`
`
`
`
`TOMCITY, OSMOTICITY, OSMOLALITY ANI GSMOLARITY
`
`1404
`
`
`
`anaasurément of phyaleal and chemical properties of salu.
`(ions Ge, colligative properties),
`‘The ad varbayge: of he w/w
`rétationship is that the coneedtration of dhe system js nek
`influenced by temperature.
`Cranelarity---The relationship observed hetwoen molal-
`ity and osmolality is shared similarly between molarity and
`aanalanity, A soludian ding an osamiglar concentration of I
`when iteontans | oanol af solute/h ofvolution. Likewlae, a
`soludion has an camolarily ofa when i conbaias 0 oxmots/L
`of solution. QOsmelar solutions, uniike aamolad solution,
`rofleet a weight in volume relationship between the solute
`and fina) soluvien, A one molar and [ osmalar solution
`would be synonymous for poncleclralytes, Mor sodium alias
`ride a] oamolar soludion would contain 7 oamol of sodium
`
`chloride per Jiter which approximates a 0.5 molar salution,
`The advantage of employing osmolar concentrations over
`
`osnotal concontrations is the ability to relate a specific num-
`ber of ogmols or millinsmols to a volume, such as a liter or
`in. hua, the osmolar concept is simpler and mare prac
`cal.
`‘The oamolal concept does not allow for this conve-
`nience becnuse of the edierelationship, Also, additional data
`gueh as the donsity usually are not avaitahle. Volumes of
`solution, maither than weights of salulion, are mare practical
`in Lhe dolivory of liquid dosage formas.
`
`Many health professionals de not have a cloar understand:
`
`ing af the differance between oamalnlity and osmolarity,
`in
`fact, the terins have bean aed interchangeally. This is due
`partly lo the eireumsianee thal, until recently, proat af the
`ayelenis invelved were body fluids, in which the difference
`batween the numerical values of the iwo concentration ox
`pressions is smalk and similar int rnagnitude,
`lo the error
`invelved iy their determination.
`‘The problem parthy may
`center around the mterprotation by some to view one kila-
`gramof water In the asimatal concept as being equivalent to|
`1, and, mare daportantly, be iterprealion Lhat to male up
`to value of 11.a4 in osmolarity, ts essontially the same as
`ihe weight of solute plas |
`liter (a distortion of the osmolal
`concept), The primary difference resides itt the error intee-
`duced which revelves around the volume af water occupied
`by the salute. AJ osmolar solution of a solute abways will be
`more concentrated than ad osmolal solution. With dilute
`solutions the difference amay be acceptably small Nine
`grams of sodium chloricde/la of uqaicous sulution i approxi
`imately equivalent iO yin G9G.G ol of water, This repre-
`sents aarroraf under 1%, when comparing the osmoticily of
`0.9%w/t solution to a solution af Ge pli | ke of water,
`
`Using dextrose ina parallel cornparigen, ertora range from
`approximately 3.5%to osmoticity with 60 ¢ dextrose/L ver.
`ship 50 w plas [ye of water to a differonee of about 25% in
`oamaticily with 260 ¢ dextrose/L. veraus 260 ¢ phis 1 ke of
`water,
`‘The confusian appears lo be without cause for con-
`cern ab Whis time, However, abe showed be alerted do the
`sizeable arrors which may eceur with eoneenteated solutions
`orfluids, auehoms those Geployed fi total parenteral nuted
`lion, enteral hypevalimentavion and oral nutritional fluids
`for infania.
`Heference has heen made Lo the terms hypertonic and
`hypotonic. Analogous Lerma are hyperosmotic and hypoos-
`matic.
`‘The sknifoance of hypere and hypo-oasmatiatyfor
`medicinal ane nutritional fluids will he discussed later, The
`valuog which correspond do hose terms for serum may be
`visualized approximately from the following example. As-
`SULLY, Hormel secuosnidlality ta be 26aamiad/hy, a8
`sorum asmololity inercases dite to water defrer, Lhe follow-
`ing signa and symptoms usually ave found to secumulate
`progressively at approximately these values:
`244 to
`998..thpred (if the patient ts alort and communicalive), 299
`to 813 -dry mucous membranes; 314 fo 329. -wealoens,
`doughy vlda; above 380. -diayrianiation, postural hypoton-
`sion, severe wealmess, fainting, ONS changes, abupor and
`
`
`
`coma. Ag serum osmolality decroases dud to waler axcess
`the following may aceur:
`275 bo 261-—-headaehe; 2020 ta
`44) --drowsiness, weakness; 260 to 206.-disenentation,
`eramps! below 283 -sekaures, atupor anc coma,
`Agindicated previously, (he mechanisms of the body ac-
`tively combat. such major changes by Hmiting the variation
`in osmolality for nermal individuals to Jess than about 1%
`(approximately ta dhe eunge 262 to 248 mOsmol/ie, based an
`the above assumption),
`he value given for nammal serum osmolality above was
`deseribed a8 an assumpden becouse ofLhe variety of values
`found in the literature. Serum osmolality ofien ia stated
`
`Jnosely to be about 300 mQsmol/l.. Apart from that, ane
`
`more s
`ally, two referancas stale it ag 280 to 266 mOn-
`
`
`mol/L; other
`references give itas 275 la 800 mOsmol/t, 280
`mOsmal/l, 306 mOsxmol/l, and 275 ta 296 mQamoi/ke.
`'Vharo ix agivong tondonay to call i osmeatatity but bo shaleit
`an mGsmal/L (iat as mCsmol/ee).
`In the light of those
`varying Values, ane nly ask about the reproducibility af the
`experimental measurements. Ht has heen slated Ghat most
`opmometers ane aceuratce do S mOsmal/l, With that type of
`roproducibilily, the above Varinddons pertiaps nay he expeet-
`ed, Phe difference between a titer and kilogram probably is
`
`jnsignifieagt for sarum and uring,
`MHis diffieult to measure
`hilograms of water in a aGlution, and easy lo exprens body
`
`Auid quantities in dite
`Perhaps no harm has been dane ta
`
`date by this practice
`for hody (huis. However, lose Cer-
`minglogy here may lead Co loose terminology when dealing
`with the rather conceanttated fluids used at dines in paren-
`teral and eoteral nutvition.
`Reference has bacon m