RESEARCH ARTICLE
`
`Formulation of a Stable Parenteral Product; Clonidine
`Hydrochloride Injection
`
`DOLORES KOSTECKAL1, MICHELLE R. DUNCAN, and DIETMAR WAGENKNECHT
`
`Pharmaceutical Sciences, Fujisawa USA, Incorporated, Melrose Park, IL
`
`ABSTRACT: Clonidine Hydrochloride Injection (Durac/0/tTM) is a cle{//; colorless, preservative-free, pyrogen free,
`aqueous solution of clonidine hydrochloride. The indication for this product is for use as an adjunct in pain
`management, administered epidurally, when opiates are insufficient. The dmg formulation was evaluated under
`both normal and stress conditions in the preformulationlfomwlation studies. The list of studies conducted includes
`a light sensitivity study, an oxygen sensitivity study. a pH/stability stlldy, a stopper compatibility evaluation, a
`freeze-thaw study, and a stability study. Samples from the light, oxygen, pH/stability, and stability studies were
`evaluated for color, visual clarity, pH, potency, and chromatographic purity. Samples from the freeze-thaw study
`were evaluated for all of the above except chromatographic purity. The results for these studies demonstrate the
`stability of the product as formulated. The pH of this unbuffered product was consistently within the acceptance
`criteria. The product remained clear and colorless for the duration of each study. The values obtained for the
`potency and chromatographic purity assays showed no evidence of degradation. The reasons for the lack of
`degradation can be found in the molecular structure of the drug substance and the fomwlation of the drug product.
`Since the molecu(ar structure is that of a Schiff base, it is theoretically possiiJ/e, although difficult, to cleave the
`molecule. A catalyst would be required, and none of the possible catalysts are present in the formulation. The
`molecule could also be cleaved upon exposure to light, and the evidence indicates that the molecule does interact
`with light. This interaction is not to the degree. lwwevet; that product stability is affected. The formulation contains
`only the active drug substance and sodium chloride in water for injection with a pH of approximately 6. Although
`the product is unbuffered, the influence of the stoppers and glass vials upon the formulation pH was minimal. In
`addition, the stopper compatibility of the product is enhanced by the absence of chelating agents, preservatives,
`acids, a11d bases. Since the dilute concentrations of both tlte active and excipiellf are well below their solubility
`limits, no solubility related issues would be expected upon freezing and subsequellf thawing. Clonidine Hydrochlo(cid:173)
`ride bzjection, as formulated, does not require protection ji"OIII light, oxygen, or freezing. The product shows
`acceptable stability witlzi11 the pH range, and the mbber closure is compatible with the product. Real time stability
`data combined with statistical projections support a 36-mollfh expiration date.
`
`Introduction
`
`In the development of a new drug product for market, it is
`necessary to evaluate the drug and the drug formulation in
`terms of stability and sensitivities under normal and stress
`conditions. The information gathered is then used to deter(cid:173)
`mine the appropriate manufacturing parameters and condi(cid:173)
`tions required to yield a stable product. This paper presents
`the formulation activities toward development of a stable
`parenteral drug product.
`is a
`Clonidine Hydrochloride Injection (DuraclonTM)
`clear, colorless, preservative-free, pyrogen-free, aqueous
`sterile solution of clonidine hydrochloride. Administered
`epidurally, Clonidine Hydrochloride Injection produces a
`powerful, dose-dependent analgesia involving non-opiate
`mechanisms (I).
`The drug substance, Clonidine Hydrochloride, USP is a
`
`R~ceived December 3, 1996. Accepted for publication April 27, 1998.
`6 Author to whom correspondence should be addressed: APP (formerly
`Fujisawa USA, Inc.), 2045 N. Cornell Ave., Melrose Park, lL60160.
`
`white to almost white crystalline powder. It is an imidazoline
`derivative with the following meso-meric structure:
`
`The molecular weight is 266.6 and the melting point is
`300°-305°C. The pK of clonidine hydrochloride is about
`8.2. The solubility is published as I gram clonidine hydro(cid:173)
`chloride being soluble in 13 mL water at 20°C (2).
`Development activities for this new drug product in(cid:173)
`cluded the evaluation of sensitivity (product instability) to
`moist-heat terminal sterilization, light, oxygen, packaging
`components (rubber stoppers), pH, and freezing. After
`determination of appropriate manufacturing parameters, the
`drug product was manufactured as for market and stability
`was evaluated to establish labeled storage temperature and
`expiration date.
`
`320
`
`PDA Journal of Pharmaceutical Science & Technology
`
`MYLAN Ex. 1012, Page 1
`
`

`
`Materials and Study Methods
`
`The Clonidine Hydrochloride Injection employed in the
`following studies was manufactured either in the laboratory
`or in a GMP production facility. The formulation consists of
`100 mcg/mL Clonidine Hydrochloride, USP, 9 mg/mL
`Sodium Chloride, USP in Water for Injection, USP. The
`product, as formulated, is consistently at about a pH of 6
`(acceptable range 5 to 7). Dilute hydrochloric acid and dilute
`sodium hydroxide solutions were used to adjust pH for the
`pH/stability study.
`The Clonidine Hydrochloride, USP used for these experi(cid:173)
`ments was obtained from a European source. The Sodium
`Chloride, USP and the solutions of sodium hydroxide and
`hydrochloric acid used for these experiments were obtained
`from 1. T. Baker located in Phillipsburg, N.J.
`The finished product is packaged as a 10 mL volume in a
`I 0-mL flint Type I ammonium sulfate treated (during vial
`manufacture) glass tubing vial sealed with a 20-mm grey
`bromobutyl rubber serum stopper. Samples manufactured in
`the GMP production facility were moist-heat terminally
`sterilized.
`
`0.\)'gen Study
`
`Three sets of vials were prepared. The first set of vials was
`purged with a mixture of 98% nitrogen/2% oxygen. The
`second set of vials was purged with oxygen. The third set of
`vials was not purged at all, making the headspace composi(cid:173)
`tion the same a~ the atmosphere, approximately 20% oxygen.
`All samples were stored at 40°C for a period of two
`weeks. At both time zero and two weeks, the samples were
`tested for oxygen headspace, color, visual clarity, pH,
`potency, and chromatographic purity.
`
`Light Study
`
`Two sets of vials were placed in the light chamber with an
`intensity of about 700 foot-candles for a duration of2 weeks.
`The first set of vials was designated as the light-exposed
`samples. The second set of vials, wrapped in aluminum foil
`to protect them from light, was designated as control samples.
`After two weeks of light exposure, the samples were
`tested for visual clarity, pH, color, potency, and chromato(cid:173)
`graphic purity.
`
`pH/Stability Study
`
`Samples were prepared at pH 4, 5, about 6 (unadjusted
`pH), 7, and 8. The samples at pH 4, 5, 7 and 8 were placed at
`55°C and tested at time zero, three weeks, and six weeks for
`visual clarity, pH, color, potency, and chromatographic
`purity. The pH 6 samples were placed at 40°C and tested at
`one, two, three and six months, as part of the overall stability
`evaluation, for visual clarity, pH, color, potency and chro(cid:173)
`matographic purity.
`
`Stopper Compatibility Evaluation
`Contact Study: A volume of Clonidine Hydrochloride
`Injection was poured over stoppers to give a surface area to
`volume ratio of 3.74 cm- 1• A second volume, the control,
`was poured into an equivalent glass vessel without stoppers.
`After 24 hours of contact at ambient temperatures, the
`
`solutions were tested for pH, color, visual clarity and assay.
`This stopper screening study was designed and presented as
`a relatively quick screen for suitable closures for longer,
`more involved compatibility evaluation. Stoppers were
`initially screened using this short-term study. An acceptable
`closure was selected for further evaluation.
`Stability Data Review: Samples manufactured in the
`GMP production facility were stored in upright and inverted
`orientations under room temperature conditions and stability
`data were collected for 24 months. From these lots, two lots
`were selected for more detailed analysis in order to deter(cid:173)
`mine the compatibility of the stopper with the product. The
`pH and assay stability results for these lots were statistically
`compared using the paired t-test method.
`
`Freeze- Thaw Study
`
`A study was conducted to determine the effects of
`freezing and subsequent thawing upon the product. The
`samples were placed at 22°C and allowed to freeze for a
`period of 18 to 24 hours. The frozen samples were then
`thawed at room temperature for 2 to 18 hours. Then, the
`samples were visually compared with unfrozen control
`samples to determine whether some visible phenomenon
`had occurred during the freezing/thawing cycle. After the
`completion of the three cycles, samples were tested for
`visual clarity, pH, color, and potency.
`
`Stability
`
`Throughout the development of this new drug product,
`Research lots and clinical lots were manufactured in a GMP
`production facility, and stored in upright and inverted
`orientations at 40 ± 2°C for three months and room
`temperature (27 ± 2°C) for a minimum of 24 months. The
`product was tested at specified intervals as defined by the
`official stability protocols. A total of 12 lots have been
`evaluated with some studies still ongoing.
`
`Assay Methods
`
`The assay for Clonidine Hydrochloride concentration and
`Chromatographic Purity was an HPLC assay using a C8 (5
`urn, 4.6 X 150 mm) column and a mobile phase of 80:20
`(v/v) Sodium 1-0ctanesulfonate (2 giL), Phosphoric acid (2
`mLIL) buffer adjusted to pH 3.0 with 2 N Sodium Hydroxide:
`Acetonitrile. The acceptance criterion during evaluation for
`Clonidine Hydrochloride Injection was a clonidine hydro(cid:173)
`chloride concentration of 90.0 to II 0.0% label claim. The
`chromatographic purity determination employed the same
`method but using a ten-fold greater sample volume. The
`chromatographic purity was tested for information only.
`Prior to submission to the FDA, a chromatographic purity
`method was validated and limits were established.
`Color was measured using a Hunter Colorimeter. The
`Yellowness Index (YI-1) is reported. The acceptance crite(cid:173)
`rion for the product is a YI-1 not more than 7.0.
`Visual clarity was evaluated in a light box illuminated by
`a 150-watt bulb. The background of the light box is white on
`the top half and black on the bottom half. The acceptance
`criterion was that the product should be clear and devoid of
`visual particulate matter.
`
`Vol. 52, No. 6 I November-December 1998
`
`321
`
`MYLAN Ex. 1012, Page 2
`
`

`
`Headspace oxygen was measured with a Macon Toray
`Oxygen Analyzer.
`
`Results
`
`Moist-Heat Terminal Sterilization
`
`This activity predated formal evaluation procedures to
`determine the ability to terminally sterilize a finished
`product, as all clinical and research batches produced were
`moist-heat terminally sterilized. A detailed decision scheme
`for determining the capability of a drug product to be
`terminally sterilized with a case study showing formulation
`changes, terminal sterilization model and cycle modifica(cid:173)
`tions presented by M. Duncan et. a!. was recently published
`(3).
`The cGMP commercial production procedure for Cloni(cid:173)
`dine Hydrochloride Injection consisted of passing the in(cid:173)
`process released bulk through a 0.45 ~m and a sterile 0.2 ~m
`nylon tortuous path membrane filters. The filtered liquid was
`filled into washed depyrogenated vials, and sealed with
`siliconized, washed stoppers and aluminum flip-off over(cid:173)
`seals. The product was finished by moist-heat terminal
`::::12
`sterilization with a cycle validated to deliver an F0
`minutes. Appropriate moist-heat terminal sterilization cycle
`development and validation were conducted by the manufac(cid:173)
`turing facility. Product stability with this process are pre(cid:173)
`sented in the stability section.
`
`Oxygen Study
`
`The results are summarized in Table I. After two weeks
`storage at 40°, no difference was found in the stability of any
`of the samples. The oxygen purged and nitrogen purged
`samples had no difference in color, clarity, or pH. Potency
`values ranged from I 01.2% label claim for the nitrogen
`purged samples to I 02.0% label claim for the oxygen purged
`samples after two weeks of exposure. There was no evidence
`of degradation, and the product was judged to be stable in
`the presence of oxygen. The presence of oxygen (>50%) or
`the absence of oxygen ( < I 0%) in the heads pace of the vials
`had no influence upon product stability. Clonidine Hydrochlo(cid:173)
`ride Injection is not sensitive to oxygen.
`
`Light Study
`
`The results are summarized in Table II. After two weeks,
`the light exposed samples and the control samples showed
`
`no difference in color, clarity, or potency. The slight
`differences found in pH (0.4 pH units) are not significant.
`The chromatogram did show an extra peak at about 13
`minutes. This indicates that there was some interaction
`between the drug product and light. The area percent of the
`extra peak, however, was about 0.13%, and the potency did
`not show a decrease. Exposure to intense light did not affect
`the overall stability of the drug product. Since the condition!>
`of the light chamber are extreme compared to the conditions
`the product will actually see, it was concluded that drug
`product does not require protection from light.
`
`pH/Swbility Study
`
`The results of this study are summarized in Table lll. The
`pH shifted toward neutrality during the course of the study.
`For example, the pH 4 sample had an initial pH of 4.09, a pH
`after three weeks of 4.22, and a pH after six weeks of 4.56.
`The observed changes in pH support the product specifica(cid:173)
`tion of 5 to 7, as this product is unbuffered. Minimal change
`in pH was found in the manufactured product as demon(cid:173)
`strated by the sample at pH 6 (no pH adjustment made).
`There was no difference in clarity, color, or potency
`between samples at pH 4, 5, 6, 7, or 8. There was no
`discernable degradation over time in any of the samples,
`despite the accelerated conditions. The chromatographic
`purity remained below the limit of quantitation for all
`samples for the duration of the study. There was no evidence
`of degradation or instability in the pH in the range of 4.6 to
`7. 7. The finished product pH specification was established as
`pH 5.0 to 7.0.
`
`Stopper Compatibility
`
`The statistical analysis of upright and inverted pH and
`assay results for two lots of Clonidine Hydrochloride
`Injection are shown in Table IV. In all cases, t was found to
`be less than t0 ,;1;cul at the 95% confidence level. There is no
`statistical difference between upright and inverted samples,
`and thus no stopper effect. The selected stopper is compat(cid:173)
`ible with Clonidine Hydrochloride Injection.
`
`Freeze-Thaw Study
`
`The data, as summarized in Table V, showed no difference
`between the unfrozen control and samples which had been
`frozen and thawed three times. All samples were clear
`without evidence of precipitation or separation. There were
`
`TABLE I
`Clonidine Hydrochloride Injection Oxygen Sensitivity Evaluation
`
`Test Criteria
`Sample
`
`Headspace
`Oxygen Results
`
`Color
`(YI-1 < 7.0)
`
`Visual Clarity
`(Clear)
`
`pH
`(5.0-7.0)
`
`Potency
`(90.0-110.0%
`Label Claim)
`
`Chromatographic
`Purity
`(Peak Area%
`For Info. Only)
`
`Initial
`Normal/ Atmosphere
`Nitrogen Purged
`Oxygen Purged
`Two weeks 40°C
`Normal/ Atmosphere
`Nitrogen Purged
`Oxygen Purged
`
`19.9%
`9.0%
`>50%
`
`20.0%
`8.8%
`>50.0%
`
`0.0
`- 1.4
`- 1.4
`
`- 1.3
`- 1.3
`- 1.4
`
`Clear
`Clear
`Clear
`
`Clear
`Clear
`Clear
`
`6.4
`6.7
`6.6
`
`6.6
`6.6
`6.6
`
`98.7
`98.8
`99.7
`
`101.4
`101.2
`102.0
`
`<0.05%
`0.3%
`0.4%
`
`<0.05%
`<0.05%
`<0.05%
`
`322
`
`PDA Journal of Pharmaceutical Science & Technolonv
`
`MYLAN Ex. 1012, Page 3
`
`

`
`TABLE II
`Clonidine Hydrochloride Injection Following Two Weeks Exposure to 700 Foot-Candles of Light
`
`Sample
`
`Initial
`Light Protected Control
`Light Exposed 700 foot-candles
`
`pH
`(5.0-7.0)
`
`6.4
`6.6
`6.2
`
`Color
`(Yl-1 < 7.0)
`0.0
`-1.3
`-1.3
`
`Visual Clarity
`(Clear)
`
`Potency
`(90.0-11 0.0%
`Label Claim)
`
`Clear
`Clear
`Clear
`
`98.7
`101.5
`101.1
`
`Chromatographic
`Purity
`(PeakArea%
`For Info. Only)
`
`<0.05
`<0.05
`0.13
`
`no observed changes in pH, color, clarity, or potency. It is
`not necessary to label this product, "Protect from Freezing."
`
`Stability
`
`The chromatographic purity method employed for these
`lots was found not rugged and unvalidatable, thus the
`invalid results are not reported here. The chromatographic
`purity method was revised prior to the manufacture of the
`three demonstration stability lots and validated for the
`NDA submission. The average chromatographic purity
`findings, for these three lots, after 24 months at room
`temperature ranged from below the 0.05% of total peak
`area limit of quantitation to 0.13% of total peak area. This
`low amount of quantifiable chromatographic impurities was
`evidence of negligible generation of drug degradation
`products.
`The statistical analysis (regression analysis) of the indi(cid:173)
`vidual lots and of pooled lots all showed small degradation
`rate constants which indicates minimal loss in potency (%
`label claim) with respect to time. After 24 months of storage
`at room temperature the average concentration (9 lots) was
`97.6% label claim for upright and 97.0% label claim for
`inverted samples. The average potency after 36 months at
`room temperature upright conditions was 99.5% label claim
`(3 lots). The statistically projected potency remains above
`95% label claim (95% confidence) through 36 months under
`room temperature storage.
`
`Discussion
`
`Chemical Drug Substance
`
`Product sensitivity to light and oxygen are dictated by the
`active drug substance. (Although a special situation may
`exist, a Pharmaceutical Scientist should not intentionally
`add a light-sensitive or oxygen-reactive excipient to a
`formulation.)
`
`Although clonidine hydrochloride is not chemically inert,
`it is stable. Clonidine hydrochloride is synthesized by the
`condensation of 1-acetyl-2-imidazolinone and 2, 6-dichloro(cid:173)
`aniline. Two routes of degradation are possible based on the
`structure. It is theoretically possible to cleave the CN bond
`by hydrolysis. Since the molecule is a Schiff base, the
`process is difficult, requiring catalysis by acid, base, alkaline
`hydrogen peroxide, ozone, or one of several other catalysts.
`(4) None of these catalysts would be found in the finished
`product. In addition, such a reaction was attempted in the
`Fujisawa USA lab, with little success. The only degradation
`that could be achieved was in the presence of hydrogen
`peroxide at elevated temperatures. Even then, the chromato(cid:173)
`gram showed no evidence of 2, 6-dichloroaniline, one of the
`anticipated products of a cleavage at the CN bond.
`Another type of cleavage can occur upon exposure to light
`(5):
`
`R'- C- R
`II
`0
`
`R'- C + R
`II
`0
`
`Since clonidine hydrochloride contains a
`
`R'- N- C- N- R
`II
`N
`and the C-N bond energy is less than that of c--c, it is a
`logical hypothesis that a similar type of cleavage can occur
`in clonidine hydrochloride. The package insert for Cata(cid:173)
`pres® tablets calls for light protection (6), indicating that
`some sort of photochemical reaction does occur. Evidence of
`clonidine hydrochloride reactivity with light was found after
`exposure to 700 foot-candles for two weeks; however, the
`amount of drug degradation was not quantifiable. The
`clonidine hydrochloride is not sufficiently reactive with
`
`TABLE Ill
`Stability of Clonidine Hydrochloride Injection from pH 4 to 8 Following 6 Weeks Storage at 55°C
`
`Sample
`
`pH
`(5.0-7.0)
`
`Visual Clarity
`(Clear)
`
`Color
`(YI-1 < 7.0)
`
`Potency
`(90.0-110.0%
`Label Claim)
`
`Chromatographic
`Purity
`(PeakArea%
`For Info. Only)
`
`Initial (time 0) pH 6 (no pH adjustment)
`pH 4
`pH 5
`pH 6 (2 months at 40°C, no pH adjustment)
`pH 7
`pH 8
`
`6.4
`4.6
`5.3
`6.3
`6.9
`7.7
`
`Clear
`Clear
`Clear
`Clear
`Clear
`Clear
`
`0.0
`-0.1
`0.1
`0.0
`-0.0
`0.0
`
`98.7
`102.4
`101. I
`100.2
`100.7
`102.3
`
`<0.05%
`<0.05%
`<0.05%
`<0.05%
`<0.05%
`<0.05%
`
`Vol. 52, No.6 I November-December 1998
`
`323
`
`MYLAN Ex. 1012, Page 4
`
`

`
`TABLE IV
`Stopper Compatibility Paired t-Test for Two Lots of Clonidine Hydrochloride Injection Stored at Room Temperature
`
`Lot A
`
`LotB
`
`Potency
`
`pH
`
`Potency
`
`pH
`
`Time (Months)
`
`3
`6
`9
`12
`18
`25
`
`UP
`
`97.3
`100.1
`101.4
`96.8
`101 .0
`99.0
`
`INV
`
`98.7
`97.5
`98.4
`98.2
`97.3
`97.8
`
`Mean
`Variance
`Pooled Variance
`df
`ttl
`P (T < = t), two tailed
`t Critical, two tailed
`
`97.98
`0.29
`
`99.27
`3.65
`-0.5187
`5
`1.408
`0.2182
`2.57
`
`UP
`
`5.8
`6.0
`6.2
`5.8
`6.3
`6.0
`
`6.02
`0.04
`
`INV
`
`5.9
`6.0
`6.2
`6.0
`6.2
`6.0
`
`6.05
`0.015
`
`0.023
`5
`0.790
`0.4650
`2.57
`
`UP
`
`96. 1
`100. 1
`95.4
`98.2
`100.4
`97.9
`
`98.02
`4. 12
`
`INV
`
`96.5
`98.9
`96.4
`98.1
`100.2
`97.6
`
`UP
`
`INV
`
`5.6
`6.5
`6.2
`6.4
`6.6
`6. 1
`
`5.9
`6.4
`6.6
`6.3
`6.6
`6.3
`
`97.95
`2. 123
`
`6.23
`0.131
`
`6.35
`0.067
`
`2.849
`5
`0.222
`0.8333
`2.57
`
`0.076
`5
`1.337
`0.2387
`2.57
`
`light, to require protection from light. This is further
`supported by the long term stability studies which showed
`Clonidine Hydrochloride Injection to remain stable as
`processed and packaged.
`The chemical structure of clonidine hydrochloride does
`not have any regions prone to nucleophilic attack, acid
`catalysis or base catalysis. Stability within the pH range of 4
`to 8 was anticipated based upon structure review.
`
`Fomwlation
`
`The formulation of C\onidine Hydrochloride Injection
`contains only the active drug substance and sodium chloride
`with a pH of approximately 6. The acceptable pH range for
`the product is equivalent to the pH range for Water For
`Injection, USP, pH 5 to 7. The pH/stability study showed the
`drug substance to be stable over an even wider pH range.
`This study also demonstrated the ability of pH to shift with
`time due to the lack of buffer capacity in the formulation. For
`Clonidine Hydrochloride Injection, the influence of the
`stoppers, glass vial and formulation upon pH was toward
`neutrality. Testing of the rubber stoppers according to USP
`<381 > "Physicochemical Test for Elastomeric Closures,"
`showed pH shifts of 0.1 pH units with water and 0.35 pH
`units with saline (7). Thus, the pH interaction of components
`is minimal, but not always negligible. Manufacturing ex peri-
`
`TABLE V
`The Effect of Three Freeze-Thaw Cycles upon Clonidine
`Hydrochloride Injection
`
`Color
`(YI-1 < 7.0)
`
`Potency
`Visual
`(90.0-110.0%
`pH
`Clarity
`(Clear) (5.0-7.0) Label Claim)
`
`ence and stability studies (Table IV) show the product to
`remain within the specified pH range of 5 to 7.
`The absence of caustic excipients, such as che\ating
`agents, preservatives, acids or bases (non neutral pH), in this
`formulation contributes to stopper compatibility. The rubber
`stopper is usually the most sensitive component with regard
`to parenteral product stability. Che\ating agents, strong salts,
`acids or bases can affect stopper integrity. The largest
`problem with preservatives is often sorption by the stopper.
`Chemical and/or physical interaction of excipients with the
`stopper can affect product pH and stability.
`The ability of the product to withstand freezing and
`thawing can be dependent upon the drug substance or the
`formulation. Protein and peptide drugs often experience
`extensive degradation during slow freezing and thawing due
`to ice crystal damage and changes in the secondary and
`tertiary structure. Emulsions and suspensions are two formu(cid:173)
`lation types which do not usually withstand freezing and
`thawing. The thermal stress often causes the emulsion to
`separate or suspended drug particles to change size. A
`concentrated liquid formulation may experience precipita(cid:173)
`tion during freezing. The ability to redissolve the precipi(cid:173)
`tated substance with thawing and the effect upon drug
`stability in the product influences whether the labeling,
`"Protect From Freezing," is required.
`Clonidine Hydrochloride Injection is very dilute with
`regard to the active drug substance. Its solubility in 9 mg/mL
`sodium chloride is 500 times greater than the product
`concentration. The sodium chloride concentration in the
`formulation, 9 mg/mL, is well below its solubility of 357
`mg/mL (8). Thus, solubility related precipitation was not
`expected upon freezing.
`
`Sample
`
`Unfrozen
`Control
`Freeze-Thaw
`Determi-
`nation #I
`Freeze-Thaw
`Determi-
`nation#2
`
`324
`
`0.0
`
`Clear
`
`6.4
`
`98.7
`
`Product Stability
`
`- 1.34
`
`Clear
`
`6.7
`
`98.3
`
`-1 .33
`
`Clear
`
`6.7
`
`99.7
`
`Screening of the drug substance for sensitivities to
`oxygen, light and pH in conjunction with a formulation
`devoid of unnecessary excipients can result in a stable
`product with a long shelf-life.
`
`PDA Journal of Pharmaceutical Science & Technology
`
`MYLAN Ex. 1012, Page 5
`
`

`
`Conclusions
`
`Development activities on a new product should include
`screening of the drug substance for sensitivities to oxygen,
`light and pH. Formulation considerations should include
`potential reactivity of the drug substance and components
`with added excipients. It is suggested, for parenteral prod(cid:173)
`ucts, to add as few excipients as possible and, when possible,
`to remain in a neutral pH range. A successfully formulated
`drug product is stable for a 24 to 36 month shelf-life.
`Clonidine Hydrochloride Injection, as formulated, does
`not require protection from light, oxygen or freezing. The
`physiological suitable pH range of 5.0 to 7.0, which
`corresponds to the unadjusted pH encountered during com(cid:173)
`pounding, is acceptable with regard to product stability.
`Compatibility with the chosen rubber closure was demon(cid:173)
`strated through long term stability study. Real-time stability
`
`data and statistical projections supported a 36-month expira(cid:173)
`tion date.
`
`References
`
`I. Duraclon<Ull Package Insert, Fujisawa USA, Inc., 1996.
`2. M. A. Abounassif, M. S. Mian, and N. A. Mian, Analytical Profiles of
`Drug Substances, Vol. 21, H. G. Brittain, Editor, Academic Press Inc.,
`NY,l992,p.112-114.
`3. M. R. Duncan, P-L. Wang, and J. E. Moldenhauer, "Determining the
`capability of a drug product to be terminally sterilized: A case study
`involving a heat sensitive, oxygen sensitive drug product," Plwrmareu(cid:173)
`tical Developmelll and Technology, Vol. 3, No. 4 ( 1998).
`4. J. March, Adl'anced Organic Chemistry, 3rd Edition, John Wiley &
`Sons, NY, 1985, p. 784-785.
`5. J. March, Advanced Organic Chemistry, 3rd Edition, John Wiley &
`Sons, NY, 1985, p. 213.
`6. Catapres® Package Insert, Boehringer Ingelheim Pharmaceuticals, Inc.,
`1990.
`7. Communication with the stopper vendor.
`8. The Merck Index, lith Edition, Merck & Co., Inc .• 1989, p. 1359.
`
`Vol. 52, No. 6 I November-December 1998
`
`325
`
`MYLAN Ex. 1012, Page 6