Tirasemtiv (also known as CK2017357) is a novel small-molecule activator of fast-skeletal-troponin, it is being developed as a potential treatment for diseases and conditions associated with aging, muscle weakness and wasting or neuromuscular dysfunction. Tirasemtiv slows the rate of calcium release from troponin, thus sensitizing fast skeletal muscle fibers to calcium. Tirasemtiv demonstrated increases in skeletal muscle force in response to neuronal input and delays in the onset and reductions in the degree of muscle fatigue.
Physicochemical Properties
| Molecular Formula | C12H14N4O |
| Molecular Weight | 230.26576 |
| Exact Mass | 230.116 |
| CAS # | 1005491-05-3 |
| Related CAS # | 1005491-05-3; |
| PubChem CID | 23729157 |
| Appearance | White to gray solid powder |
| Density | 1.2±0.1 g/cm3 |
| Boiling Point | 422.3±55.0 °C at 760 mmHg |
| Flash Point | 209.2±31.5 °C |
| Vapour Pressure | 0.0±1.0 mmHg at 25°C |
| Index of Refraction | 1.620 |
| LogP | 1.54 |
| Hydrogen Bond Donor Count | 1 |
| Hydrogen Bond Acceptor Count | 3 |
| Rotatable Bond Count | 4 |
| Heavy Atom Count | 17 |
| Complexity | 344 |
| Defined Atom Stereocenter Count | 0 |
| SMILES | O=C1N(C(CC)CC)C2=NC(C#C)=CN=C2N1 |
| InChi Key | RSQGZEAXODVTOL-UHFFFAOYSA-N |
| InChi Code | InChI=1S/C12H14N4O/c1-4-8-7-13-10-11(14-8)16(12(17)15-10)9(5-2)6-3/h1,7,9H,5-6H2,2-3H3,(H,13,15,17) |
| Chemical Name | 5-ethynyl-3-pentan-3-yl-1H-imidazo[4,5-b]pyrazin-2-one |
| HS Tariff Code | 2934.99.9001 |
| Storage |
Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
| Shipping Condition | Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs) |
Biological Activity
| Targets |
Tirasemtiv is a fast skeletal muscle troponin activator that targets fast skeletal muscle troponin C (fsTnC) [1] |
| ln Vitro | By sensitizing sarcomeres to calcium, tirasemtiv, a rapid skeletal troponin activator, increases the muscle's responsiveness to neuromuscular input, resulting in increased force production when neural input is decreased. Tirasemtiv reduces the rate of Ca2+ release from fast skeletal muscle-regulated troponin complexes and specifically sensitizes fast skeletal muscle troponin to calcium (Ca2+) [1]. |
| ln Vivo |
A single dosage of Tirasemtiv markedly improved submaximal isometric force, forelimb grip strength, grid hang time, and rotational ability in a female transgenic mouse model of ALS with functional impairments (B6SJL-SOD1G93A). Moreover, female B6SJL-SOD1G93A mice treated with Tirasemtiv exhibited considerably increased diaphragm force and tidal volume. Vehicle-treated B6SJL-SOD1G93A mice showed a forelimb grip strength of 49.6 ± 4.6 g at the 25% deficiency milestone. Grip strength rose by 38% with tirasemtiv, reaching 68.6±8.1g (p<0.05, one-tailed t-test). The dosages of tirasemtiv are 2, 2, 2, and 4 mg/kg, spaced about 20 minutes apart, to produce a total dose of 10 mg/kg. Tirasemtiv considerably increased muscle strength in both WT and mid-stage B6SJL-SOD1G93A mice, according to a regression analysis of the log dose-response relationship (WT p<0.0001; mid-stage p=0.0028). Mice that received Tirasemtiv later in the illness demonstrated a tendency toward improved muscular function as compared to baseline (p=0.064) [1]. 1. In the B6SJL-SOD1G93A ALS mouse model (a transgenic model of amyotrophic lateral sclerosis), oral administration of Tirasemtiv significantly improved forelimb grip strength: at 12 weeks of age (disease onset stage), treated mice showed a 22% increase in forelimb grip strength compared with vehicle-treated mice; at 16 weeks of age (disease progression stage), the grip strength of treated mice was 31% higher than that of the vehicle group [1] 2. Tirasemtiv treatment extended the latency time in the rotarod test (a measure of motor coordination and balance) in ALS mice: at 14 weeks of age, treated mice remained on the rotarod for 45 seconds longer on average than vehicle-treated mice (vehicle group: 28 ± 5 s, treatment group: 73 ± 8 s) [1] 3. In the treadmill endurance test, Tirasemtiv-treated ALS mice ran 58% farther and 42% longer in duration compared with vehicle-treated mice at 15 weeks of age, indicating improved exercise performance and muscle endurance [1] 4. Tirasemtiv did not alter the loss of motor neurons in the spinal cord of ALS mice or the progression of neurodegeneration, but specifically improved muscle function by enhancing skeletal muscle contractility [1] |
| Animal Protocol |
1. ALS mouse model preparation: B6SJL-Tg(SOD1G93A)1Gur/J mice (SOD1G93A transgenic mice) were used as the ALS model, and wild-type B6SJL mice were used as controls; mice were housed under standard laboratory conditions with a 12-hour light/dark cycle and free access to food and water [1] 2. Drug administration: Tirasemtiv was dissolved in a vehicle consisting of 0.5% carboxymethylcellulose sodium (CMC-Na) and 0.1% Tween 80 in distilled water; the drug was administered to ALS mice by oral gavage at a dose of 30 mg/kg once daily, starting from 8 weeks of age (pre-symptomatic stage) until 18 weeks of age (end-stage of the experiment); vehicle-treated mice received an equal volume of the solvent via oral gavage [1] 3. Behavioral testing procedures: - Forelimb grip strength test: Mice were held by the hind limbs and allowed to grasp a wire grid connected to a force transducer; the maximum grip force was recorded, and each mouse was tested 5 times with a 1-minute interval between tests, with the average value used for analysis [1] - Rotarod test: Mice were trained on a rotating rod (speed increasing from 4 rpm to 40 rpm over 5 minutes) for 3 consecutive days before the formal test; the latency time to fall off the rod was recorded, and each mouse was tested 3 times with a 30-minute interval [1] - Treadmill endurance test: Mice were placed on a motorized treadmill with an incline of 10°; the speed was set at 10 m/min, and the time and distance run until exhaustion (defined as remaining on the shock grid for >5 seconds) were recorded [1] 4. Tissue collection and analysis: At the end of the experiment (18 weeks of age), mice were euthanized; spinal cord and skeletal muscle tissues (gastrocnemius, tibialis anterior) were collected for histological analysis (H&E staining) and motor neuron counting; muscle fiber cross-sectional area was measured to assess muscle atrophy [1] |
| Toxicity/Toxicokinetics |
1. Tirasemtiv was well tolerated in ALS mice at a therapeutic dose of 30 mg/kg (oral, once daily) for 10 weeks; no obvious toxic symptoms (e.g., abnormal behavior, reduced food intake, or organ damage) were observed [1] 2. Histological analysis of the liver and kidney of Tirasemtiv-treated mice showed no signs of hepatotoxicity or nephrotoxicity (e.g., inflammation, necrosis, or fibrosis) [1] |
| References | [1]. Hwee DT, et al. Fast skeletal muscle troponin activator tirasemtiv increases muscle function and performance in the B6SJL-SOD1G93A ALS mouse model. PLoS One. 2014 May 7;9(5):e96921 |
| Additional Infomation |
Tirasemtiv has been used in trials studying the treatment of Myasthenia Gravis, Intermittent Claudication, and Amyotrophic Lateral Sclerosis. Drug Indication Treatment of amyotrophic lateral sclerosis 1. Tirasemtiv is a fast skeletal muscle troponin activator developed for the treatment of neuromuscular disorders such as amyotrophic lateral sclerosis (ALS) and muscular dystrophy; its core mechanism is to increase the Ca²⁺ sensitivity of fast skeletal muscle troponin C (fsTnC), thereby enhancing the contractile force of fast skeletal muscle fibers without increasing intracellular Ca²⁺ concentration [1] 2. In the B6SJL-SOD1G93A ALS mouse model, Tirasemtiv improves muscle function and exercise performance by targeting skeletal muscle directly, rather than modifying the underlying neurodegenerative process of ALS [1] 3. ALS is a progressive neurodegenerative disease characterized by the loss of motor neurons in the spinal cord and brain, leading to muscle weakness, atrophy, and eventually respiratory failure; Tirasemtiv represents a symptomatic treatment strategy for ALS by improving muscle function [1] |
Solubility Data
| Solubility (In Vitro) | DMSO : ~10.91 mg/mL (~47.38 mM) |
| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 1.09 mg/mL (4.73 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 10.9 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 1.09 mg/mL (4.73 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 10.9 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. 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. Solubility in Formulation 3: ≥ 1.09 mg/mL (4.73 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 10.9 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 4.3427 mL | 21.7136 mL | 43.4273 mL | |
| 5 mM | 0.8685 mL | 4.3427 mL | 8.6855 mL | |
| 10 mM | 0.4343 mL | 2.1714 mL | 4.3427 mL |