Drug compounds have included stable heavy isotopes of carbon, hydrogen, and other elements, mostly as quantitative tracers while the drugs were being developed. Because deuteration may have an effect on a drug's pharmacokinetics and metabolic properties, it is a cause for concern [1].

Absorption, Distribution and Excretion
Ivacaftor is well absorbed in the gastrointestinal tract. Following administration of ivacaftor with fat-containing foods, peak plasma concentrations were reached at 4 hours (Tmax) with a maximum concentration (Cmax) of 768 ng/mL and AUC of 10600 ng * hr/mL. It is recommended that ivacaftor is taken with fat-containing foods as they increase absorption by approximately 2.5- to 4-fold.
After oral administration, ivacaftor is mainly eliminated in the feces after metabolic conversion and this elimination represents 87.8% of the dose. From the total eliminated dose, the metabolites M1 and M6 account for the majority of the eliminated dose, being 22% for M1 and 43% for M6. Ivacaftor shows negligible urinary excretion as the unchanged drug.
After oral administration of 150 mg every 12 hours for 7 days to healthy volunteers in a fed state, the mean (±SD) for apparent volume of distribution was 353 (122) L.
The CL/F (SD) for the 150 mg dose was 17.3 (8.4) L/hr in healthy subjects.

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Metabolism / Metabolites
Ivacaftor is extensively metabolized in humans. In vitro and clinical studies indicate that ivacaftor is primarily metabolized by CYP3A. From this metabolism, the major formed metabolites are M1 and M6. M1 is considered pharmacologically active even though it just presents approximately one-sixth the effect of the parent compound ivacaftor. On the other hand, M6 is not considered pharmacologically active as it represents less than one-fiftieth of the effect of the parent compound.

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Biological Half-Life
In a clinical study, the apparent terminal half-life was approximately 12 hours following a single dose of ivacaftor. One source mentions the half-life ranges from 12 to 14 hours.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Maternal ivacaftor therapy produce low levels in milk and very low levels in the serum of breastfed infants. An international survey of cystic fibrosis centers found no adverse effects in breastfed infants of mothers taking these drugs and a task force respiratory experts from Europe, Australia and New Zealand found that these drugs are probably safe during breastfeeding. One breastfed infant had transient elevations in bilirubin and liver enzymes during maternal therapy that could not definitively be attributed to the drugs in breastmilk. Until more data are available, monitoring of infant bilirubin and liver enzymes might be advisable during breastfeeding with maternal ivacaftor therapy. Congenital cataracts in breastfed infants has been reported in the infants of mothers who took the drug during pregnancy, so examination of breastfed infants for cataracts has been recommended. Anecdotal evidence indicates that the drugs in breastmilk may moderate cystic fibrosis in breastfed infants.
◉ Effects in Breastfed Infants
A woman with cystic fibrosis was treated with lumacaftor and ivacaftor during pregnancy and postpartum. Her infant was fully breastfed until day 29 postpartum when elevated direct and indirect bilirubin, aspartate aminotransferase (AST), and alkaline phosphatase were found to be elevated. All values had been normal on days 1 and 14. The fraction of breastmilk the infant received was reduced to 25% and all values were normal on day 37. The fraction of breastfeeding was increased to 50% and then to 100%. On day 135, the infant's direct bilirubin was elevated during concurrent maternal levofloxacin and trimethoprim-sulfamethoxazole therapy. The fraction of breastfeeding was decreased to 75% and the direct bilirubin was normal on day 154. The authors noted that the abnormal test results could not definitively be attributed to lumacaftor and ivacaftor therapy.
A survey was sent to lead clinicians of adult CF centers in Europe, the United Kingdom, United States of America, Australia and Israel requesting anonymized data on pregnancy outcomes in women using CFTR modulators during pregnancy and lactation. Responses were received from 31 centers and one woman with CF for a total of 64 pregnancies in 61 women resulting in 60 live births. Thirteen infants were breastfed on ivacaftor alone, 9 infants were breastfed on lumacaftor and ivacaftor, and 5 infants were breastfed on tezacaftor and ivacaftor for a total of 27 infants exposed to ivacaftor in breastmilk, all with no reported complications. The extent of breastfeeding was not reported. An updated survey by the same authors asked CF clinicians to report on pregnant women exposed to the elexacaftor, tezacaftor and ivacaftor combination during pregnancy and breastfeeding. Twenty-six infants were breastfed (extent not stated) during maternal use of the combination. No adverse effects were reported in the breastfed infants.
An infant was born to a mother taking elexacaftor, ivacaftor and tezacaftor for cystic fibrosis. The infant was breastfed (extent not stated). Although the infant had cystic fibrosis-causing CFTR mutations, the infant was healthy and tested negative for cystic fibrosis on newborn screening. The authors expressed concern that the drugs received transplacentally and in breastmilk caused a false negative screening test.
A mother who was a heterozygous carrier of the F508del gene became pregnant with a homozygous infant. At 32 weeks of pregnancy, the mother began elexacaftor, ivacaftor and tezacaftor in the usual adult dosage to treat her fetus who had evidence of meconium ileus. The infant was born at 36 weeks and given pancreatic enzyme replacement therapy with breastfeeding while maternal treatment continued. The infant’s fecal elastase, transaminases and bilirubin were normal at about 1 month of age. The infant’s sweat chloride, although low, was nearer to normal than was expected. The authors hypothesized that the medications received in breastmilk moderated the disease process in the infant.
Three women with cystic fibrosis were taking elexacaftor, ivacaftor and tezacaftor in unspecified dosages during pregnancy and postpartum while breastfeeding. On routine visual examinations between 8 days and 6 months postpartum, their infants were found to have small (<1.0 mm) bilateral cataracts, in the central area in one and outside the visual axis in the other two. Breastfeeding was discontinued after diagnosis at 16 days, 9 weeks and 6 months postpartum. The contribution of breastfeeding to the cataracts could not be determined.
Two women were reported by the British Columbia cystic fibrosis clinic who became pregnant and breastfed their infants. One took ivacaftor and breastfed (extent not stated) for 42 months. Her infant was physically normal and healthy, but had speech delay. The other woman took Tricafta (ivacaftor, elexacaftor, and tezacaftor). She breastfed (extent not stated) her infant for 6 months and her infant had no complications.
A woman with cystic fibrosis took ivacaftor 150 mg, tezacaftor 100 mg and elexacaftor 200 mg in the morning and ivacaftor 150 mg at night during pregnancy and breastfeeding (extent not stated). The infant had not regained his birthweight at 10 days postpartum, his stools had a greasy rim and he had pancreatic elastase levels below levels for pancreatic sufficiency but higher than usually expected for newborns homozygous for this mutation. The infant was started on pancreatic enzymes and by day 20, he had normal elastase levels. By day 45 of life was gaining weight and stools were normal. At 6 months of age the infant was still being breastfed and doing well. The authors felt that when breastfeeding is stopped, a rebound in symptoms might occur because the infant will no longer be receiving small amounts of the mother’s medications through milk.
A woman with cystic fibrosis received elexacaftor 100 mg, tezacaftor, 50 mg, ivacaftor 75 mg and additional ivacaftor 150 mg daily from 12 weeks of pregnancy and postpartum. The mother exclusively breastfed her infant while continuing therapy, and no significant side effects related were observed in the infant up to at least 3 months of age.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
About 99% of ivacaftor is bound to plasma proteins, primarily to alpha 1-acid glycoprotein and albumin.

[1]. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019 Feb;53(2):211-216.

[2]. Functional defect of variants in the adenosine triphosphate-binding sites of ABCB4 and their rescue by the cystic fibrosis transmembrane conductance regulator potentiator, ivacaftor (VX-770). Hepatology. 2017 Feb;65(2):560-570.

Ivacaftor is an aromatic amide obtained by formal condensation of the carboxy group of 4-oxo-1,4-dihydroquinoline-3-carboxylic acid with the amino group of 5-amino-2,4-di-tert-butylphenol. Used for the treatment of cystic fibrosis. It has a role as a CFTR potentiator and an orphan drug. It is a quinolone, a member of phenols, an aromatic amide and a monocarboxylic acid amide.
Ivacaftor (also known as Kalydeco or VX-770) is a drug used for the management of Cystic Fibrosis (CF). It is manufactured and distributed by Vertex Pharmaceuticals. It was approved by the Food and Drug Administration on January 31, 2012, and by Health Canada in late 2012. Ivacaftor is administered as a monotherapy and also administered in combination with other drugs for the management of CF. Cystic Fibrosis is an autosomal recessive disorder caused by one of several different mutations in the gene for the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein, an ion channel involved in the transport of chloride and sodium ions across cell membranes. CFTR is active in epithelial cells of organs such as of the lungs, pancreas, liver, digestive system, and reproductive tract. Alterations in the CFTR gene result in altered production, misfolding, or function of the protein and consequently abnormal fluid and ion transport across cell membranes. As a result, CF patients produce thick, sticky mucus that clogs the ducts of organs where it is produced making patients more susceptible to complications such as infections, lung damage, pancreatic insufficiency, and malnutrition. Prior to the development of ivacaftor, management of CF primarily involved therapies for the control of infections, nutritional support, clearance of mucus, and management of symptoms rather than improvements in the underlying disease process or lung function (FEV1). Notably, ivacaftor was the first medication approved for the management of the underlying causes of CF (abnormalities in CFTR protein function) rather than control of symptoms.
Ivacaftor is a Cystic Fibrosis Transmembrane Conductance Regulator Potentiator. The mechanism of action of ivacaftor is as a Chloride Channel Activation Potentiator, and Cytochrome P450 2C9 Inhibitor, and P-Glycoprotein Inhibitor, and Cytochrome P450 3A Inhibitor.
See also: Ivacaftor; lumacaftor (component of); Elexacaftor, ivacaftor, tezacaftor; ivacaftor (component of); Ivacaftor; ivacaftor, tezacaftor (component of).

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Drug Indication
When used as monotherapy as the product Kalydeco, ivacaftor is indicated for the treatment of cystic fibrosis (CF) in patients aged one month and older who have one mutation in the CFTR gene that is responsive to ivacaftor potentiation based on clinical and/or _in vitro_ assay data. When used in combination with the drug [lumacaftor] as the product Orkambi, ivacaftor is indicated for the management of CF in patients aged one year and older who are homozygous for the _F508del_ mutation in the CFTR gene. If the patient’s genotype is unknown, an FDA-cleared CF mutation test should be used to detect the presence of the _F508del_ mutation on both alleles of the CFTR gene. When used in combination with [tezacaftor] in the product Symdeko, it is used to manage CF in patients 12 years and older who have at least one mutation in the CFTR gene or patients aged 12 or older who are shown to be homozygous for the F508del mutation. When used in combination with tezacaftor and [elexacaftor] in the product Trikafta, it is indicated for the treatment of cystic fibrosis in patients 12 years of age and older who have at least one _F508del_ mutation in the CFTR gene.
Kalydeco tablets are indicated: As monotherapy for the treatment of adults, adolescents, and children aged 6 years and older and weighing 25 kg or more with cystic fibrosis (CF) who have an R117H CFTR mutation or one of the following gating (class III) mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene: G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N or S549R (see sections 4. 4 and 5. 1). In a combination regimen with tezacaftor/ivacaftor tablets for the treatment of adults, adolescents, and children aged 6 years and older with cystic fibrosis (CF) who are homozygous for the F508del mutation or who are heterozygous for the F508del mutation and have one of the following mutations in the CFTR gene: P67L, R117C, L206W, R352Q, A455E, D579G, 711+3A→G, S945L, S977F, R1070W, D1152H, 2789+5G→A, 3272 26A→G, and 3849+10kbC→T. In a combination regimen with ivacaftor/tezacaftor/elexacaftor tablets for the treatment of adults, adolescents, and children aged 6 years and older with cystic fibrosis (CF) who have at least one F508del mutation in the CFTR gene (see section 5. 1). Kalydeco granules are indicated for the treatment of infants aged at least 4 months, toddlers and children weighing 5 kg to less than 25 kg with cystic fibrosis (CF) who have an R117H CFTR mutation or one of the following gating (class III) mutations in the CFTR gene: G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N or S549R (see sections 4. 4 and 5. 1). In a combination regimen with ivacaftor/tezacaftor/elexacaftor for the treatment of cystic fibrosis (CF) in paediatric patients aged 2 to less than 6 years who have at least one F508del mutation in the CFTR gene.
Treatment of cystic fibrosis

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Mechanism of Action
A wide variety of CFTR mutations correlate to the Cystic Fibrosis phenotype and are associated with differing levels of disease severity. The most common mutation, affecting approximately 70% of patients with CF worldwide, is known as F508del-CFTR or delta-F508 (ΔF508), in which a deletion in the amino acid phenylalanine at position 508 results in impaired production of the CFTR protein, thereby causing a significant reduction in the amount of ion transporter present on cell membranes. Ivacaftor as monotherapy has failed to show a benefit for patients with delta-F508 mutations, most likely due to an insufficient amount of protein available at the cell membrane for interaction and potentiation by the drug. The next most common mutation, G551D, affecting 4-5% of CF patients worldwide is characterized as a missense mutation, whereby there is sufficient amount of protein at the cell surface, but opening and closing mechanisms of the channel are altered. Ivacaftor is indicated for the management of CF in patients with this second type of mutation, as it binds to and potentiates the channel opening ability of CFTR proteins on the cell membrane. Ivacaftor exerts its effect by acting as a potentiator of the CFTR protein, an ion channel involved in the transport of chloride and sodium ions across cell membranes of the lungs, pancreas, and other organs. Alterations in the CFTR gene result in altered production, misfolding, or function of the protein and consequently abnormal fluid and ion transport across cell membranes. Ivacaftor improves CF symptoms and underlying disease pathology by potentiating the channel open probability (or gating) of CFTR protein in patients with impaired CFTR gating mechanisms. The overall level of ivacaftor-mediated CFTR chloride transport is dependent on the amount of CFTR protein at the cell surface and how responsive a particular mutant CFTR protein is to ivacaftor potentiation.

C24H10D18N2O3

410.60

410.323

1413431-05-6

Ivacaftor;873054-44-5;Ivacaftor-d4

16220172

White to off-white solid powder

212-215

5.154

3

4

4

29

671

0

PURKAOJPTOLRMP-UHFFFAOYSA-N

InChI=1S/C24H28N2O3/c1-23(2,3)16-11-17(24(4,5)6)20(27)12-19(16)26-22(29)15-13-25-18-10-8-7-9-14(18)21(15)28/h7-13,27H,1-6H3,(H,25,28)(H,26,29)

N-(2,4-ditert-butyl-5-hydroxyphenyl)-4-oxo-1H-quinoline-3-carboxamide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)