In rats, tenapanor hydrochloride (0.15, 0.5 mg/kg; po) decreases the absorption of phosphate from passive paracellular sources[1]. Rats given tenapanor hydrochloride (0.15 mg/kg; po; twice daily for 11 days in a row) have a greater decrease in the excretion of phosphorus in their urine [2].
Tenapanor HCl (CAS#: 1234365-97-9) in vivo: In healthy rats, tenapanor (0.15 mg/kg bid, 4 days) reduced urinary phosphate excretion across increasing dietary phosphate concentrations (0.15-1.5 M oral bolus) and at different dietary phosphate intakes, indicating inhibition of paracellular phosphate absorption. [1]
In rat enteropooling study (high-phosphate meal), tenapanor (0.15 mg/kg) reduced urinary phosphate and sodium excretion, increased cecal delivery of sodium, phosphate, water, and luminal phosphate concentration, while decreasing cecal potassium concentration (no effect on calcium or magnesium). [1]
Tenapanor (0.5 mg/kg) reduced radioactive phosphate absorption in rat jejunum in vivo loop model; sodium-free buffer produced similar effect. [1]
Tenapanor (0.5 and 10 mg/kg) inhibited 33P absorption but did not affect 3H-mannitol absorption in rats. [1]
In healthy human volunteers, tenapanor (15 mg twice daily for 4 days) significantly increased mean daily stool phosphorus excretion and decreased mean daily urinary phosphorus and sodium excretion, with no effect on urinary potassium excretion. [1]
In rats, tenapanor (0.3 mg/kg/day) combined with sevelamer (0.75-3% w/w in diet) dose-dependently reduced urinary phosphorus excretion; synergy was observed (Bliss model). Tenapanor alone reduced urinary phosphorus by 33.2% (4-day mean) and urinary sodium by 82.1%. [2]
In rats acclimated to sevelamer (1.5% w/w for 6 days), addition of tenapanor (0.15 mg/kg bid, 7 days) reduced residual urinary phosphorus excretion by 37±6%. Tenapanor (0.5 mg/kg bid) reduced urinary phosphorus even after binder discontinuation. [2]

Tenapanor HCl (CAS#: 1234365-97-9) enzyme/NHE3 functional assays: NHE3-mediated proton efflux was measured in human intestinal epithelial stem cell-derived enteroid monolayers using the pH-sensitive dye BCECF-AM. After acid loading in sodium-free media, recovery of intracellular pH upon addition of sodium-containing media was monitored (excitation 490/440 nm, emission 535 nm). Tenapanor concentration-response curves were generated, and IC50 values calculated. [1]
NHE3-mediated apical acid secretion was monitored by color change of phenol red in apical media or by BCECF-AM fluorescence ratio decrease. [1]
Paracellular ion permeability was measured by dilution potential and bionic potential in Ussing chambers. Sodium chloride dilution potentials were generated by replacing apical NaCl with mannitol; phosphate bionic potentials were generated by replacing apical phosphate with gluconate. Permeability ratios were calculated using Kimizuka-Koketsu equation. [1]

Tenapanor inhibits paracellular phosphate flux in an intestinal epithelial cellular model
Intestinal epithelial stem cells from human or mouse gastrointestinal biopsies cultured as monolayers allow for monitoring of ion transport across the intestinal epithelium. The enteroid monolayer contains the diversity of intestinal epithelial cell lineages, models the specific gene expression patterns of each individual intestinal segment, expresses the appropriate endogenous ion transporters (for example, NHE3 and NaPi2b) in a segment-specific manner, polarizes to form tight junctions with segment-specific expression of claudins and other tight junction proteins, and generates the expected negative luminal electrical potential observed in vivo. The differentiated enteroid monolayer therefore enables the study of transcellular and paracellular phosphate absorption[1].

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Human intestinal epithelial stem cell-derived enteroid monolayer culture (Kozuka et al., 2017): Human duodenum and ileum biopsies were used to generate stem cell cultures, differentiated on Transwell filters. Monolayers were washed with phosphate-free media, treated with tenapanor (1 μM, DMSO vehicle control) apically for 4 h or overnight. Apical and basolateral ion concentrations measured by ion chromatography; TEER recorded with volt/ohm meter; pH measured with pH meter; transepithelial potential difference measured in Ussing chambers. Phosphate flux calculated from concentration change and volume. [1]
Mouse ileum monolayers were similarly cultured. For NaPi2b activity studies, initial apical phosphate 1-5 mM, basolateral 1 mM. Tenapanor (1 μM) or NTX-9066 (1 μM) added for 4 h, 2 days, or 3 days. [1]
NHE3 knockout human ileum monolayers were generated using CRISPR/Cas9 targeting NHE3 exon 2; loss of NHE3 protein and function confirmed by Western blot and absence of apical acidification. [1]
Intracellular pH (pHi) measurement: Cells loaded with BCECF-AM (2 μM, 30 min), then acid-loaded with NH4Cl pulse or sodium-free media, and pHi recovery upon sodium addition recorded. Tenapanor added 5 min before recovery. [1]
Radioactive phosphate absorption in rat jejunum loop: Rats anesthetized, jejunum loop ligated, injected with 33P (0.5 μCi) ± tenapanor (10 μM) or sodium-free buffer, incubated 30 min, radioactivity in loop and plasma measured. [1]
Urinary excretion studies in rats: Rats fed high-phosphate diet (1.1% w/w total phosphate), treated with tenapanor (0.15 or 0.3 mg/kg bid) or vehicle, with or without sevelamer in diet (0-3% w/w). Urine collected over 24 h in metabolic cages, sodium and phosphorus measured by ion chromatography. [1][2]
Enteropooling study: Rats trained to eat high-phosphate meal (1.2% P), treated with tenapanor (0.15 mg/kg) or vehicle, sacrificed at 2,4,6,8 h post-meal; cecal contents collected for ion concentration and water volume measurement. [1]
Intestinal glucose absorption: Rats fed 4-h standardized meal, small intestinal contents collected, glucose measured. [1]
Hollow fiber model (for HCMV, not applicable; not tenapanor).

Animal/Disease Models: Rats (intestinal loop model)[1]
Doses: 0.15, 0.5 mg/kg
Route of Administration: Po
Experimental Results: decreased passive paracellular phosphate absorption by decreased urinary phosphate and sodium excretion after the high-phosphate meal and increased sodium and phosphate delivery to the cecum.

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Animal/Disease Models: 8 weeks, 250 g male Sprague–Dawley rats[2]
Doses: 0.15 mg/kg in combination with sevelamer (0%, 0.75%, 1.5%, and 3% (wt/wt ))
Route of Administration: po (oral gavage); twice-daily for 11 days
Experimental Results: Dramatically augmented the reduction in urinary phosphorus excretion.

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Tenapanor HCl (CAS#: 1234365-97-9) animal protocols: Rat studies used male Sprague Dawley rats (approx. 250 g). Tenapanor was formulated as a suspension in 0.5% Tylose or in 0.01% Tween 80 (acidified water) and administered orally by gavage twice daily (bid) at volumes of 5 or 10 mL/kg. Doses ranged from 0.15 to 10 mg/kg per administration. [1][2]
High-phosphate diet: Standard rodent chow spiked with additional 0.4% inorganic phosphate (1:1 sodium:potassium salt) to achieve 1.1% w/w total phosphate. For sevelamer combination, sevelamer carbonate was mixed into powdered diet at 0%, 0.75%, 1.5%, or 3% w/w. [2]
Metabolic cage studies: Rats were housed individually in metabolic cages for 24-h urine collection after 2-day acclimation. Food and water intake measured daily. [2]
In vivo loop model: Rats anesthetized with isoflurane, jejunum loop (5 cm) ligated, injected with 0.5 mL of phosphate solution containing 33P (0.5 μCi) ± tenapanor (10 μM) or sodium-free buffer. After 30 min, loop excised, radioactivity counted. [1]
Enteropooling study: Rats trained to eat a fixed high-phosphate meal (5 g, 1.2% P) within 15 min. Tenapanor (0.15 mg/kg) or vehicle given 1 h before meal. At 2,4,6,8 h after meal, rats euthanized, cecum removed, contents weighed and analyzed. [1]
Healthy human volunteer study: Single-center, randomized, open-label, three-way crossover study (NCT02249936). Healthy adults (19-65 years) received tenapanor HCl tablet 15 mg twice daily before standardized meals for 4 days. 24-h urine and stool collections performed daily. [1]

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
After oral administration, tenapanol is almost entirely not absorbed systemically, and plasma concentrations are undetectable. Systemic absorption of tenapanol is extremely low, and it does not expose breastfed infants to clinically significant drug exposure. No special precautions are required.
◉ Effects on Breastfed Infants
As of the revision date, no relevant published information was found.
◉ Effects on Lactation and Breast Milk
As of the revision date, no relevant published information was found.

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Tenapanor HCl (CAS#: 1234365-97-9) was well tolerated in rat studies at doses up to 100 mg/kg bid (no clinical signs of toxicity, food and water intake similar to uninfected controls). In acute toxicity studies, no data provided. In healthy human volunteers, tenapanor 15 mg bid for 4 days was generally well tolerated; adverse events not detailed but no serious safety signals reported. [1] No specific LD50 or organ toxicity data reported. [1][2]

[1]. Inhibition of sodium/hydrogen exchanger 3 in the gastrointestinal tract by tenapanor reduces paracellular phosphate permeability. Sci Transl Med. 2018 Aug 29;10(456):eaam6474.

[2]. Combination treatment with tenapanor and sevelamer synergistically reduces urinary phosphorus excretion in rats. Am J Physiol Renal Physiol. 2021 Jan 1;320(1):F133-F144.

See also: Tenapano (with active fraction).

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Tenapanor HCl (CAS#: 1234365-97-9) is a minimally absorbed, locally acting NHE3 inhibitor. It reduces paracellular phosphate permeability by increasing transepithelial electrical resistance (TEER) via intracellular acidification resulting from NHE3 inhibition. This effect is rapid, reversible, and does not involve tight junction protein trafficking or endocytosis. Tenapanor does not affect NaPi2b-mediated active phosphate transport directly but reduces NaPi2b expression after repeated dosing (approx. 30% decrease in rat jejunum/ileum). In healthy humans, tenapanor increases stool phosphorus and decreases urinary phosphorus. It is under clinical development for hyperphosphatemia in patients with chronic kidney disease on dialysis (phase 3 trials: NCT03427125, NCT02675998). In combination with sevelamer, tenapanor acts synergistically to reduce intestinal phosphate absorption. [1][2]

C50H68CL6N8O10S2

1217.9705247879

1214.263

C, 49.31; H, 5.63; Cl, 17.46; N, 9.20; O, 13.14; S, 5.26

1234365-97-9

Tenapanor;1234423-95-0

78131177

Typically exists as white to off-white solids at room temperature

8

14

29

76

1770

2

ClC1=CC(=CC2=C1CN(C)C[C@H]2C1C=CC=C(C=1)S(NCCOCCOCCNC(NCCCCNC(NCCOCCOCCNS(C1=CC=CC(=C1)[C@H]1C2C=C(C=C(C=2CN(C)C1)Cl)Cl)(=O)=O)=O)=O)(=O)=O)Cl.Cl.Cl

VFRAXTZDILCRKY-OWRGXFNZSA-N

InChI=1S/C50H66Cl4N8O10S2.2ClH/c1-61-31-43(41-27-37(51)29-47(53)45(41)33-61)35-7-5-9-39(25-35)73(65,66)59-15-19-71-23-21-69-17-13-57-49(63)55-11-3-4-12-56-50(64)58-14-18-70-22-24-72-20-16-60-74(67,68)40-10-6-8-36(26-40)44-32-62(2)34-46-42(44)28-38(52)30-48(46)54;;/h5-10,25-30,43-44,59-60H,3-4,11-24,31-34H2,1-2H3,(H2,55,57,63)(H2,56,58,64);2*1H/t43-,44-;;/m0../s1

3-((S)-6,8-dichloro-2-methyl-1,2,3,4-tetrahydroisoquinolin-4-yl)-N-(26-((3-((S)-6,8-dichloro-2-methyl-1,2,3,4-tetrahydroisoquinolin-4-yl)phenyl)sulfonamido)-10,17-dioxo-3,6,21,24-tetraoxa-9,11,16,18-tetraazahexacosyl)benzenesulfonamide dihydrochloride

RDX 5791; AZD 1722; RDX-5791; AZD-1722; RDX5791; AZD1722; Ibsrela; Tenapanor hydrochloride; Tenapanor dihydrochloride

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

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

H2O : ~20 mg/mL (~16.42 mM)

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.)