CENTER FOR DRUG EVALUATION AND
`RESEARCH
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`APPLICATION NUMBER:
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`203496Orig1s000
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`PHARMACOLOGY REVIEW(S)
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`DEPARTMENT OF HEALTH
`& HUMAN SERVICES
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`Food and Drug Administration
`Center for Drug Evaluation and Research
`Office of Drug Evaluation I
`Division of Cardiovascular and Renal Products
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` Memorandum
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`March 20, 2013
`
`Thomas Papoian, PhD, DABT
`Supervisory Pharmacologist
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`NDA 203496 (Treprostinil diethanolamine)
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`Date:
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`From:
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`To:
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`Subject:
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`1. Background
`
`Treprostinil diethanolamine (NDA 203496; United Therapeutics Corp.), an analogue of
`prostacyclin (PGI2) with potent vasodilatory as well as platelet antiaggregatory effects, was
`submitted to this Division (DCRP) on Dec. 24, 2011, as a sustained release oral tablet for the
`treatment of pulmonary arterial hypertension (PAH). Treprostinil had been approved previously
`for the treatment of PAH by the subcutaneous, intravenous, and inhalational routes of
`administration. The current oral formulation is different from the previous sodium salt
`formulations in that it uses the diethanolamine salt
`
`
`On March 7, 2013, this reviewer was notified by Mr. Dan Brum (DCRP Regulatory Project
`Manager) that on June 22, 2012, diethanolamine (CAS No. 111-42-2) was listed by the Office of
`Environmental Health Hazard Assessment (OEHHA) of the State of California as a chemical
`known to cause cancer. During the course of the NDA review cycle, the sponsor coincidentally
`changed the name of the drug to treprostinil diolamine, one of several commonly used chemical
`names for diethanolamine.
`
`Other chemical names for diethanolamine include:
`- Diolamine
`- Bis(hydroxyethyl)amine
`- N,N-Bis(2-hydroxyethyl)amine
`- 2,2'-Dihydroxydiethylamine
`- β,β'-Dihydroxydiethylamine
`- N-Ethylethanamine
`- 2-[(2-Hydroxyethyl)amino]ethanol
`
`
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`
`
`Listing of diethanolamine (diolamine) as known by the State of California to
`cause cancer (according to Proposition 65) - June 22, 2012
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`
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`Reference ID: 3279937
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`1
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`(b) (4)
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`

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`- 2,2'-Iminobisethanol
`- Iminodiethanol
`
`
`Proposition 65, the Safe Drinking Water and Toxic Enforcement Act of 1986, was enacted as a
`California State ballot initiative in November 1986. The Proposition was intended to protect
`California citizens and the state's drinking water sources from chemicals known to cause cancer,
`birth defects or other reproductive harm, and to inform citizens about exposures to such
`chemicals. Proposition 65 requires the Governor to publish, at least annually, a list of chemicals
`known to the State to cause cancer or reproductive toxicity.
`
`The safety, particularly carcinogenic risk, of treprostinil diethanolamine (now diolamine) when
`given to PAH patients at recommended doses is reviewed below.
`
`2. Toxicity Profile of Diethanolamine
`
`
`Diethanolamine
`
`
`
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`CAS No. 111-42-2
`Chemical formula: C4H11NO2
`MW: 105.14
`
`
`Diethanolamine (DEA) is an organic compound synthesized from a reaction of ethylene oxide
`and ammonia. In contrast to naturally-occurring ethanolamine (monoethanolamine; MEA), a
`common head group for cell membrane phospholipids that is synthesized endogenously,
`diethanolamine is not known to occur naturally. However, it is widely used in the preparation of
`diethanolamides and diethanolamide salts of long-chain fatty acids, such as coconut oil
`diethanolamine condensates (cocomide DEA), that are formulated into soaps, detergents,
`cosmetics, shampoos, hair conditioners, and in many other industrial uses (reviewed in IARC,
`2012). For example, diethanolamine as a contaminant can constitute up to 18% of cocomide
`DEA.
`
`CFSAN/FDA permits use of diethanolamine as a component of adhesives in food packaging and
`as an indirect food additive when food comes into contact with paper products containing
`diethanolamine (21 CFR Parts 175.105, 176.170, 176.180).
`
` A
`
` search of currently approved drug labels did not find any drugs stating that they contained
`diethanolamine or diolamine. However, according to the FDA's database of inactive ingredients
`used in approved brand-name and generic drug products (i.e., Inactive Ingredient Guide), 1.5%
`aqueous diethanolamine solutions are used as solvents for drugs given intravenously, in topical
`creams at 0.3%, and in ophthalmic solutions.
`
`Animal toxicity studies with diethanolamine have been conducted going back many decades
`(reviewed in Mathews et al., 1997; IARC 2000, 2012a). In 1992, the National Toxicology
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`Reference ID: 3279937
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`Program (NTP) conducted 13-week subchronic toxicity studies with diethanolamine in B6C3F1
`mice and F344/N rats following dermal and oral (via drinking water) administration (Melnick et
`al., 1994a and 1994b). Doses administered were as follows:
`- Mice:
`- Drinking water = 630-10,000 ppm = 100-1700 mg/kg
`- Dermal (5X/wk) = 80-1250 mg/kg
`
`- Rats:
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`- Drinking water = 160-5000 ppm = 15-440 mg/kg
`- Dermal (5X/wk) = 32-500 mg/kg
`
`
`Results (as stated in the PubMed abstracts) showed that diethanolamine induced dose-dependent
`toxic effects in multiple organs in both species (Table 1).
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`Table 1
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`Results of 13-Week Toxicity Studies with Diethanolamine in Mice and Rats
`(Melnick et al., 1994a and 1994b)
`
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`Species Tissue
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`Effects
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`NOAEL Dose
`Achieved?
`(Yes/No)
`No
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`The predominant target organs of toxicity were liver in mice, and kidney in both species, the two
`tissues with the highest concentrations (up to one-third of the administered oral dose) of
`diethanolamine. Interestingly, no liver lesions were seen in rats by either route of exposure. In
`rats, diethanolamine produced greater toxicity when given in the drinking water when compared
`to topical application. This was attributed largely to the limited dermal absorption of the
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`Reference ID: 3279937
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`3
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`Mouse
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`Liver
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`Rat
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`Kidney
`Heart
`Skin
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`Blood
`Kidney
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`Brain and
`spinal cord
`Testis
`Skin
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`Hepatocellular cytological alterations and necrosis;
`multiple hepatocyte changes, including enlarged
`cells that were frequently multinucleated, increased
`nuclear pleomorphism, increased eosinophilia and
`disruption of hepatic cords
`Nephropathy and tubular epithelial necrosis in males Yes
`Cardiac myocyte degeneration
`Yes
`Site of application: ulceration, inflammation,
`No
`hyperkeratosis, and acanthosis
`Poorly regenerative, microcytic anemia
`Increased weight, tubular necrosis, decreased renal
`function, and/or tubular mineralization
`Demyelination
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`No
`No
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`Yes
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`Yes
`No
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`Degeneration of the seminiferous tubules
`Site of application: ulceration, inflammation,
`hyperkeratosis and acanthosis
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`chemical through rat skin. However, little difference in toxicity between the two routes (oral or
`dermal) was noted in mice, which was thought to be due to thinner skin in mice vs. rats.
`
`Subsequent absorption and bioavailability studies in mice and rats were conducted using oral,
`dermal and intravenous dosing in rats, and dermal dosing only in mice (Mathews, et al., 1997).
`Dermal application of diethanolamine used a wire mesh to prevent oral absorption through
`grooming, in contrast to the NTP carcinogenicity studies were grooming of the applied area was
`allowed. Results showed that diethanolamine is 100% absorbed from the GI tract, absorption
`through skin increased with increasing doses (i.e., diethanolamine enhances its own absorption),
`absorption of total dose through thinner mouse skin (26.8-58.1%) is greater than thicker rat skin
`(2.9-16.2%), and that diethanolamine has significant potential for bioaccumulation following
`repeated exposure, a reflection of diethanolamine's long half-life (7 days for various tissues and
`up to 54 days in blood). Published exposure estimates of diethanolamine from human daily use
`of shampoo products (e.g., cocomide DEA) varied widely from 8-200 mg/kg/day to 0.2-2.0
`µg/kg/day (reviewed in IARC, 2012a).
`
`Diethanolamine is excreted essentially unchanged, whereas the naturally-occurring ethanolamine
`is converted to CO2 (10-15%), with the remainder incorporated into phospholipids. The toxicity
`of diethanolamine was thought to be due to high tissue accumulation, and incorporation and
`accumulation of O-phosphorylated and N-methylated diethanolamine into aberrant phospholipids
`resulting in alterations in membrane structure and function (Mathews, et al., 1997; reviewed in
`IARC, 2012).
`
`Due to this reported toxicity in subchronic animal studies and continuing widespread human
`exposure, particularly in the industrial workplace and through skin care products, diethanolamine
`was selected by NTP for carcinogenic evaluation (NTP, 1999). Male and female B6C3F1 mice
`and F344/N rats were administered diethanolamine in ethanol dermally 5 days/week for 2 years.
`Mice received diethanolamine at 0, 40, 80, or 160 mg/kg, and rats received 0, 16, 32, or 64
`mg/kg (males) or 0, 8, 16, or 32 mg/kg (females).
`
`Other than irritation at the site of application, no significant pathologic findings or increased
`tumors were seen in rats, presumably due to limited dermal absorption of diethanolamine
`through rat skin.
`
`In mice, however, incidences of the following tumors, when compared to vehicle controls, were
`either significantly increased or showed a positive trend:
`Male mice:
`- Hepatocellular adenoma and hepatocellular adenoma and carcinoma (combined)
`in all dose groups (significantly increased).
`- Hepatoblastoma in mid-dose (80) and high-dose (160 mg/kg) groups
`(significantly increased).
`- Renal tubule adenoma (positive trend).
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`Reference ID: 3279937
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`Female mice:
`- Hepatocellular adenoma and hepatocellular adenoma and carcinoma (combined)
`in all dose groups (significantly increased).
`
`A summary of the neoplastic and non-neoplastic findings from the NTP mouse and rat
`carcinogenicity studies with diethanolamine is shown in Table 2 below.
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`Reference ID: 3279937
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`Table 2 (NTP. 1999)
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`Reference ID: 3279937
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`The NTP Working Group noted that tumors of the kidney and hepatoblastomas are considered
`rare tumors in rodents. NTP concluded that ethanolamine showed "clear evidence" of
`carcinogenic activity (NTP, 1999).
`
`
`
` A
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` full battery of genetic toxicity studies with diethanolamine were also conducted by NTP and
`were all found to be negative (i.e., Ames test, mouse lymphoma assay, sister chromatid
`exchanges, chromosomal aberrations in CHO cells, and mouse micronucleous assay) (NTP,
`1999).
`
`Given that diethanolamine is a contaminant in coconut oil diethanolamine condensates
`(cocomide DEA) that are used in many everyday household products, NTP conducted mouse and
`rat carcinogenicity studies with coconut oil acid diethanolamine condensate (NTP, 2001).
`Results were similar to those seen with diethanolamine, that is, no tumors were seen in rats, but
`increased hepatocellular adenomas, hepatocellular carcinomas, hepatoblastomas, and renal
`tubule adenomas and renal tubule carcinomas were seen in mice. The increases were attributed
`to the free diethanolamine present as a contaminant at levels up to 18.2% (IARC, 2012b).
`
`3. Possible Mechanisms for Mouse Tumor Data
`
`Subsequent to the publication of the NTP mouse tumor results in 1999, several investigators,
`including some from chemical companies, published reports examining possible modes of action
`for the carcinogenic effects seen in mice with diethanolamine (reviewed in IARC, 2000). These
`studies in mice showed that diethanolamine induced a choline deficiency in B6C3F1 mice, and
`that diethanolamine inhibited uptake of choline into mammalian cells in culture. These data
`together with previous reports that choline deficiency in the diet of rodents predisposes to
`development of hepatocellular carcinomas, and of "inadequate evidence" for carcinogenicity in
`humans, prompted the International Agency for Research on Cancer (IARC), an agency that is
`part of the World Health Organization (WHO), to conclude that diethanolamine-induced choline
`deficiency provided a plausible mechanism for the tumorigenesis seen in mice, but not rats, and
`that diethanolamine is not classifiable as to its carcinogenicity to humans" (IARC, 2000).
`
`Subsequent data was published supporting the premise that diethanolamine induced mouse liver
`tumors by a non-genotoxic mechanism that involves its ability to cause choline deficiency
`(Leung et al., 2005). The evidence included the following: (1) diethanolamine decreased hepatic
`choline metabolites and S-adenosylmethionine (SAM) levels in mice, similar to those observed
`in choline-deficient mice, whereas no effect was seen in the rat, a species in which
`diethanolamine was not carcinogenic; (2) all doses of diethanolamine that induced tumors in
`mice were shown to cause choline deficiency; (3) diethanolamine decreased phosphatidylcholine
`synthesis by blocking the cellular uptake of choline in vitro, but not in the presence of excess
`choline; and (4) diethanolamine induced transformation in the Syrian hamster embryo cells,
`increased S-phase DNA synthesis in mouse hepatocytes, and decreased gap junctional
`intracellular communication in primary cultured mouse and rat hepatocytes, but all these events
`were prevented with choline supplementation. Finally, it was suggested that rodents are more
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`Reference ID: 3279937
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`susceptible to choline deficiency than humans due to quantitative differences in the enzyme
`kinetics controlling choline metabolism.
`
`In 2012, IARC re-evaluated more recent evidence relating to the diethanolamine's proposed
`carcinogenic mode of action in mice and its possible relevance for humans (IARC, 2012a). In
`addition to effects of diethanolamine on structure and function of biological membranes, the
`proposed mechanism for its carcinogenic effects in mice postulated that depletion of intracellular
`choline levels leads to reduced availability of the methyl donor SAM, resulting in
`hypomethylation of DNA, altered expression of genes that regulate cell growth, and possible
`tumor formation through epigenetic mechanisms.
`
`The arguments for this proposed mechanism based on the published literature were summarized
`as follows (reviewed in IARC, 2012):
`- Dermal exposure of mice to maximum tolerated doses of diethanolamine resulted in
`reductions in levels of choline, choline metabolites and SAM in the liver.
`- The induction of morphological transformation in SHE cells by diethanolamine was
`prevented by the addition of excess choline.
`- The inhibition of choline uptake by diethanolamine in SHE and Chinese hamster ovary
`cells was prevented by the addition of excess choline to the culture medium.
`- DNA methylation status was similarly altered (mainly hypomethylations) in isolated
`mouse hepatocytes grown in the presence of diethanolamine or in choline-deficient
`medium.
`- Increases in DNA synthesis in primary cultures of mouse or rat hepatocytes
`incubated with diethanolamine were prevented by the addition of excess choline.
`- N-nitrosodiethanolamine, a potent carcinogen created by the reaction between
`diethanolamine and sodium nitrite, was not detected in mice that were administered
`diethanolamine by dermal application with or without sodium nitrite in their drinking-
`water, indicating the mouse tumors were not due to in vivo formation of this carcinogen.
`
`However, "uncertainties" were raised about the choline deficiency mechanism based on the
`published literature (reviewed in IARC, 2012):
`- No effect on hepatic levels of SAM was observed in mice administered a dose of
`diethanolamine (40 mg/kg) that produced a significant increase in hepatocellular
`neoplasms.
`- Studies of induced choline deficiency have not been evaluated in mouse kidney, the
`second site of tumor induction by diethanolamine in mice.
`- Although rats are highly sensitive to choline deficiency, the 2 year carcinogenicity
`study of diethanolamine found no evidence of a liver tumor response in this species.
`- The hallmark of dietary choline deficiency is a fatty liver. However, a fatty liver was
`not diagnosed in rats or mice exposed to diethanolamine.
`- The detection of mutations in the β-catenin gene in liver tumors from diethanolamine-
`exposed mice indicates that in vivo mutagenesis may be involved. No studies have been
`reported on the mutational profile in liver tumors induced in mice fed a choline-deficient
`diet.
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`Reference ID: 3279937
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`Given that there appeared to be "weak evidence" for a genotoxic mechanism for the induction of
`liver tumors by diethanolamine in mice, and "moderate experimental evidence" for a choline
`deficiency mechanism, IARC concluded that relevance of this mechanism for humans "cannot be
`excluded", especially for subgroups that are highly susceptible to dietary choline deficiency. The
`final evaluation of IARC in 2012 was that: (1) there is "inadequate evidence" for carcinogenicity
`of diethanolamine in humans, (2) there is "sufficient evidence" in animals, and (3)
`diethanolamine is "possibly carcinogenic" to humans (Group 2B).
`
`Based on this 2012 IARC report, and according to Prop 65, California's Office of Environmental
`Health Hazard Assessment (OEHHA) on June 22, 2012, listed diethanolamine (CAS No. 111-
`42-2) as a chemical known to cause cancer in either humans or animals.
`
`4. Assessment of Potential Carcinogenic Risk from Use of Treprostinil Diethanolamine by
`PAH Patients
`
`The lowest dose that produced liver tumors (hepatocellular adenoma and carcinoma) in the NTP
`mouse carcinogenicity study was 8 mg/kg/day when given dermally 5X/wk for 2 years.
`Depending on dose (i.e., there was increased absorption with increasing dose), the percentage of
`diethanolamine absorbed through the skin of mice was determined to be in the range of 26.8-
`58.1%. Given that absorption of diethanolamine in the GI tract has been reported to be 100%
`(Mathews, et al., 1997), and taking the lowest value of 26.8% absorbed, the orally equivalent
`dose of a 8 mg/kg/day dermally-applied dose would be 2.1 mg/kg/day (= 6.3 mg/m2), the lowest
`orally-equivalent dose in which mouse liver tumors were seen.
`
`The recommended dose of treprostinil diethanolamine for PAH patients is 3.4 mg BID or 6.8
`mg/day. This equals 0.11 mg/kg, when based on a 60 kg individual. The proportion of
`diethanolamine (MW 105.14) to treprostinil diethanolamine (MW 495.65) is 0.21. Therefore, a
`daily dose of 0.11 mg/kg/day of treprostinil diethanolamine constitutes a daily dose of 0.02
`mg/kg/day diethanolamine in humans (= 0.74 mg/m2). Therefore, the lowest orally-equivalent
`dose of diethanolamine that produced liver tumors in mice (6.3 mg/m2) is 9X the recommended
`daily dose of diethanolamine in PAH patients (0.74 mg/m2). It should be noted that a NOAEL
`dose for liver tumors in mice was not identified, therefore, the safety margin is likely to be less
`than 9X the human dose.
`
`As part of the carcinogenic assessment for treprostinil diethanolamine (NDA 203496), a 26-week
`transgenic mouse study was conducted in Tg.rasH2 mice at oral doses of 5, 10 and 20 mg/kg/
`day in males and 3, 7.5 and 15 mg/kg/day in females. When compared to vehicle controls, no
`significantly increased incidence of tumors was seen, whereas the positive control urethane
`showed the expected increase in tumor incidence. As mentioned, the proportion of
`diethanolamine (MW 105.14) to treprostinil diethanolamine (MW 495.65) is 0.21. The highest
`NOAEL dose of 20 mg/kg/day treprostinil diethanolamine from the transgenic mouse study
`represents 4.2 mg/kg/day diethanolamine (= 12.6 mg/m2). When compared to the recommended
`daily dose of diethanolamine in PAH patients (0.74 mg/m2), the NOAEL from the 26-week
`transgenic mouse study represents a safety margin of 17X. Further, there were no other non-
`neoplastic findings in the livers of these mice. However, given that diethanolamine has
`significant potential for bioaccumulation following repeated exposure, a reflection of
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`Reference ID: 3279937
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`diethanolamine's long half-life, and its non-genotoxic mode of action, tumorigenic effects may
`not become manifest within a 6 month study. A two year carcinogenicity study with treprostinil
`diethanolamine in rats has been initiated, but not yet completed. Results from this rat study
`should be informative regarding carcinogenic potential of the diethanolamine salt as a
`component of treprostinil given orally, but without the issue of limited dermal absorption seen in
`the NTP rat study. However, the high dose selected in the study is limited by the
`pharmacological (i.e., vasodilatory) and/or toxicological (i.e., GI toxicity) effects of treprostinil
`as a prostacyclin (PGI2) analogue.
`
`5. Conclusions
`
`Treprostinil as the sodium salt (Remodulin and Tyvaso) has been approved for continuous
`subcutaneous, continuous intravenous, and inhalational routes of administration. However,
`rodent carcinogenic studies were not previously conducted due to the difficulty of conducting
`lifetime continuous s.c. or i.v. administration in rodents. Also, the expected lifespan of untreated
`PAH patients was stated by the sponsor to be only 3 years at the time of approval. The
`exemption for not having to conduct rodent carcinogenicity studies in this case was according to
`an ICH carcinogenicity guidance (ICH-S1A; March 1996) that no long-term carcinogenicity
`studies may be required in instances where the life-expectancy in the indicated population is
`short (i.e., less than 2 to 3 years).
`
`However, for the current oral formulation using the diethanolamine counterion, it was agreed by
`the FDA (Nov. 2005) and EMA (Feb. 2006) that carcinogenicity studies need to be ongoing at
`the time of NDA submission. Six-month transgenic mouse studies were submitted with the NDA
`and reviewed. Two-year rat carcinogenicity studies are ongoing.
`
`The tumors seen in mice after two years of dermal administration of diethanolamine in the NTP
`study was postulated to be due to non-genotoxic mechanisms as a result of depleted intracellular
`choline levels leading to reduced availability of the methyl donor SAM, hypomethylation of
`DNA, and altered expression of genes that regulate cell growth (IARC, 2000a). Patients with
`choline deficiency appear to be at greater risk, but whether some patients with PAH are deficient
`in dietary choline (e.g., vegetarians) has not been examined. Also, doses of diethanolamine
`associated with liver tumors in mice were at least 9X the human daily dose, although a NOAEL
`dose was not identified. However, the risk of cancer for PAH patients with relatively short life
`expectancies, if correct, may be limited.
`
`6. Additional Comment
`
`The cancer risk from exposure to diethanolamine in PAH patients given treprostinil
`diethanolamine may be relatively limited given: (1) the non-genotoxic mechanism of depleted
`intracellular choline levels for its tumorigenic effect in mice, (2) its relevancy for PAH patients
`who may not be choline deficient, and (3) the short life expectancy of PAH patients. However,
`there is another concern for use of diethanolamine in other pharmaceutical products, such as the
`1.5% aqueous diethanolamine solutions that are currently used as solvents for drugs given
`intravenously.
`
`
`
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`Reference ID: 3279937
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`10
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`

`

`As mentioned, diethanolamine was found in rodents to be toxic to many tissues, including liver,
`kidney, heart, skin, blood, brain, spinal cord, testis, and skin. The toxicity of diethanolamine was
`thought to be due to high tissue accumulation resulting from its long half-life, and incorporation
`and accumulation of diethanolamine into aberrant phospholipids leading to alterations in
`membrane structure and function (Mathews, et al., 1997; reviewed in IARC, 2012). Such effects
`are likely to occur at any dose, and may result in serious toxicities, particularly when given
`intravenously or repeatedly over longer periods of time. It is not clear how safety was
`determined for its use as a drug solvent for intravenous use in products that may include
`formulations for generic drugs or as part of drug compounding. Although occupational exposure
`limits via skin and inhalational exposures have been established (IARC, 2012a), detailed
`information regarding human effects following intended therapeutic administration of
`diethanolamine does not appear to be readily available, but is worthy of further investigation as a
`separate matter.
`
`
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`Reference ID: 3279937
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`11
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`

`

`7. References
`
`International Agency for Research on Cancer (IARC) Monograph; Diethanolamine; v.77; 2000.
`
`International Agency for Research on Cancer (IARC) Monograph; Diethanolamine; v.101;
`2012a.
`
`
`International Agency for Research on Cancer (IARC) Monograph; Coconut oil diethanolamine
`condensate; v.101; 2012b.
`
`
`Lehman-McKeeman LD et al.; Diethanolamine induces hepatic choline deficiency in mice;
`Toxicol. Sci. 2002; 67:38-45.
`
`
`Leung HW et al.; review of the carcinogenic activity of diethanolamine and evidence of choline
`deficiency as a plausible mode of action; Reg. Toxicol. Pharmacol. 2005; 43:260-271.
`
`
`Mathews JM et al.; Diethanolamine absorption, metabolism and disposition in rat and mouse
`following oral, intravenous and dermal administration; Xenobiotica 1997; 27:733-746.
`
`
`Melnick RL et al.; Toxicity of diethanolamine. 2. Drinking water and topical application
`exposures in F344 rats; J. Appl. Toxicol. 1994; 14:1-9.
`
`
`Melnick RL et al.; Toxicity of diethanolamine. 2. Drinking water and topical application
`exposures in B6C3F1 mice; J. Appl. Toxicol. 1994; 14:11-19.
`
`
`National Toxicology Program (NTP); Toxicology and carcinogenesis studies of diethanolamine
`(CAS No. 111-42-2) in F344/N rats and B6C3F1 mice (dermal studies); NTP Technical
`Report 478; July 1999.
`
`
`National Toxicology Program (NTP); Toxicology and carcinogenesis studies of coconut oil acid
`diethanolamine condensate (CAS No. 68603-42-9) in F344/N rats and B6C3F1 mice
`(dermal studies); NTP Technical Report 479; Jan. 2001.
`
`
`Newberne PM; Choline deficiency associated with diethanolamine carcinogenicity; Toxicol. Sci.
`2002; 67:1-3.
`
`
`Stott WT et al.; Potential mechanisms of tumorigenic action of diethanolamine in mice; Toxicol.
`Lett. 2000: 114:67-75.
`
`
`
`
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`Reference ID: 3279937
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`---------------------------------------------------------------------------------------------------------
`This is a representation of an electronic record that was signed
`electronically and this page is the manifestation of the electronic
`signature.
`---------------------------------------------------------------------------------------------------------
`/s/
`----------------------------------------------------
`
`THOMAS PAPOIAN
`03/21/2013
`
`Reference ID: 3279937
`
`

`

`
`
`
`
`
`DEPARTMENT OF HEALTH AND HUMAN SERVICES
`PUBLIC HEALTH SERVICE
`FOOD AND DRUG ADMINISTRATION
`CENTER FOR DRUG EVALUATION AND RESEARCH
`
`
`PHARMACOLOGY/TOXICOLOGY NDA REVIEW AND EVALUATION
`
`
`Application number:
`Supporting document/s:
`
`Applicant’s letter date:
`CDER stamp date:
`Product:
`
`Indication:
`Applicant:
`
`Review Division:
`Reviewer:
`Supervisor/Team Leader:
`Division Director:
`Project Manager:
`
`NDA 203496
`# 0 (original submission); #s 3, 4 & 5 (non-clinical -
`carcinogenicity and safety pharm. info.) # 14 (GI
`irritation study)
`12/24/2011
`12/27/2011
`TM (treprostinil diolamine) sustained release
`tablets for oral administration
`Treatment of pulmonary arterial hypertension
`United Therapeutics Corp., Research Triangle Park,
`NC
`Division of Cardiovascular and Renal Products
`Xavier Joseph, D.V.M.
`Thomas Papoian, Ph.D.
`Norman Stockbridge, M.D., Ph.D.
`Dan Brum, Pharm.D.
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`Disclaimer
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`Except as specifically identified, all data and information discussed below and necessary for
`approval of NDA 203496 are owned by United Therapeutics, Corp. or are data for which United
`Therapeutics has obtained a written right of reference. Any information or data necessary for
`approval of NDA 203496 that United Therapeutics does not own or have a written right to
`reference constitutes one of the following: (1) published literature, or (2) a prior FDA finding of
`safety or effectiveness for a listed drug, as reflected in the drug’s approved labeling. Any data or
`information described or referenced below from reviews or publicly available summaries of a
`previously approved application is for descriptive purposes only and is not relied upon for
`approval of NDA 203496.
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`Reference ID: 3198769
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`NDA # 203496
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`TABLE OF CONTENTS
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`1. EXECUTIVE SUMMARY …………………………………………. 3
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`2. DRUG INFORMATION ………………………………………….. 7
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`3. PHARMACOLOGY ………………………………………….. 9
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`4. PHARMACOKINETICS …………………………………………. 14
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`5. GENERAL TOXICOLOGY ……………………………………….. 18
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`6. GENETICS TOXICOLOGY ……………………………………… 43
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`7. CARCINOGENICITY …………………………………………. 46
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`8. REPRODUCTIVE AND DEVELOPMENTAL TOXICOLOGY .. 59
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`9. SPECIAL TOXICOLOGY STUDIES ……………………………… 97
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`10. INTEGRATED SUMMARY ………………………………………. 98
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`Reference ID: 3198769
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`NDA # 203496
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`EXECUTIVE SUMMARY
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`Introduction
`1.1
`Treprostinil diethanolamine (UT-15C) is being developed as a sustained release oral tablet for
`the treatment of pulmonary arterial hypertension (PAH). Treprostinil sodium (Remodulin®
`Injection), a chemically stable analogue of prostacyclin (PGI2) with potent vasodilatory as well
`as platelet antiaggregatory effects, has been approved for chronic administration either by
`continuous subcutaneous or intravenous infusion for the treatment of PAH. Tyvaso®
`(treprostinil) Inhalation Solution has also been approved for the treatment of PAH by the
`inhalation route. The active pharmaceutical ingredient present in treprostinil diethanolamine and
`treprostinil sodium is shown to be identical (ionized treprostinil) irrespective of the salt used.
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`1.2 Brief Discussion of Nonclinical Findings
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`In a comparative study in anesthetized rats, the effects of treprostinil (treprostinil sodium) and
`UT-15C (treprostinil diethanolamine) on systemic arterial blood pressure and heart rate were
`studied to determine whether changing the salt form of treprostinil would change the bioactivity
`of treprostinil. The results indicated that the diethanolamine salt produced a similar
`cardiovascular profile to treprostinil following iv administration. This study also showed that
`UT-15C was active when administered via the intraduodenal (ID) route; the action was slower
`than the iv route while the duration of action was longer compared to iv route.
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`The hemodynamic effects of six human metabolites were evaluated in the same rat model. All
`metabolites evaluated had a significantly reduced activity (~ 1000 fold) compared to UT-15C.
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` A
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` cardiovascular safety pharmacology study in beagle dogs, did not reveal any changes in ECG
`morphology or cardiac rhythm. UT-15C did not inhibit hERG-mediated current at doses up to
`300 µM, the highest dose used in the study.
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`Cardiovascular safety studies conducted with diethanolamine alone did not produce any changes
`in arterial pressure, heart rate, EKG parameters including QTc, at doses up to 4 mg/kg/day,
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`The bioavailability (BA) studies in rats showed that UT-15C has an absolute BA of about 10%
`when given orally in solution. Intraportal vein BA was found to be approximately 40%,
`suggesting a substantial first pass effect.
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`Tissue distribution studies using dual-radiolabeled UT-15C showed that the distribution of drug-
`derived radioactivity for both labels was widespread, and both labels crossed blood/brain and
`blood/testes barriers.
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`In vitro protein binding studies using dual-labeled UT-15C showed that [14C]-treprostinil
`component of UT-15C was highly bound to human plasma proteins with mean binding of
`approximately 96%, while the [3H]-diethanolamine component was minimally bound to human
`plasma proteins (mean binding of 6.1%).
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`Reference ID: 3198769
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`NDA # 203496
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`In vitro metabolite characterization studies showed that treprostinil was rapidly metabolized by
`rat, dog and human liver microsomes to five metabolites present in all species, suggesting similar
`metabolic potential of treprostinil across these spec