Research Article |
Corresponding author: Mithun Rudrapal ( rsmrpal@gmail.com ) Academic editor: Plamen Peikov
© 2022 Sunil Kumar Karumuri Taraka, Praveen Kumar Pasala, Ranjan Kumar Sahoo, Umesh D. Laddha, Shubham J. Khairnar, Atul R. Bendale, Mithun Rudrapal.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Taraka SKK, Pasala PK, Sahoo RK, Laddha UD, Khairnar SJ, Bendale AR, Rudrapal M (2022) Atorvastatin ascorbic acid cocrystal strategy to improve the safety and efficacy of atorvastatin. Pharmacia 69(2): 295-302. https://doi.org/10.3897/pharmacia.69.e80072
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The study was aimed to investigate the effect of dissolution enhancement on the hypolipidemic effect and hepatotoxicity of the drug in hyperlipidemic rats. Atorvastatin ascorbic acid cocrystals were prepared by phase solution methods and characterized by Fourier transformation infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, X-Ray powder diffraction. Results of characterization confirmed that atorvastatin ascorbic acid cocrystals exhibited particle size was 221 nm. In in vitro study, results of dissolution test showed that the release of atorvastatin was increased to 1.6 folds. From In vivo study results, it was observed that in atorvastatin ascorbic acid cocrystals treated rats, serum total cholesterol, triglycerides, liver transaminase levels were significantly decreased, and liver glutathione activity was increased. In conclusion, atorvastatin ascorbic acid cocrystals therapy exhibited less hepatotoxicity in presence of ascorbic acid when compared to atorvastatin alone therapy and also the efficacy of therapy was improved.
cocrystal technology, atorvastatin, ascorbic acid, atorvastatin ascorbic acid cocrystals
Atorvastatin is a synthetic lipid modifier that has been approved for atherosclerosis and cardiovascular disease as an effective therapy. It acts by inhibiting β-hydroxy β-methylglutaryl CoA reductase, which results in lower serum total and LDL cholesterol, apoB and triglyceride levels while increasing HDL cholesterol levels. The drug has poor water solubility with a recorded solubility value of 0.011 mg/L with low solubility and a high intestinal clearance and metabolism of the first pass. The drug has a narrow absorption window in accordance with the biopharmaceutical classification system (
Atorvastatin (Aurabindo Pharma, India). Ascorbic acid, Methanol (Loba Chemie, Mumbai, India). Total Cholesterol, Triglycerides, SGOT, SGPT Kits (Coral Clinical system, Tulip Diagnostics, Hyderabad), Wistar albino rats (Mahaveer Enterprises, Hyderabad).
Co-crystal formation was achieved using phase solubility studies, equimolar ratio of atorvastatin and ascorbic acid (1:1) were dissolved in methanol and stirred under slight heating until a clear solution was obtained. The solution is immediately filtered using a funnel and whatman filter paper. The solution is allowed to dry overnight at room temperature. The obtained cocrystals were stored in desiccators until they were characterized.
Co- crystals were dissolved in methanol (1 mg / ml), volume adjusted to 50 ml distilled water and filtered through a membrane filter of 0.45μm. Drug content was quantified using double beam UV-Visible Spectrophotometer (at 246 nm) (Shimadzu-1800, Japan) (
Powdered samples were compressed to disks after mixing with potassium bromide of spectroscopic grade. The FT-IR (Alpha-E Bruker FT-IR) spectra of these disks were recorded in the range of 4000 to 400 cm-1, under potassium bromide diffuse reflectance mode using a pyloelectric detector. The collected data were analyzed using FT-IR spectroscopy Software.
Powdered samples (2 mg) were encapsulated in an aluminum pan that was crimped onto the furnace before mounting. The samples have been heated from 30 °C to 200 °C at a rate of 10 °C per minute. The thermal events were monitored with dry nitrogen flowing at a rate of 20 ml/min (DSC (TA SDT 2960 DSC (USA). The whole process was under computer control employing Pyris software for recording and analyzing the data.
Powder samples were mounted on double sided adhesive tape and sputter coated with gold palladium thin layer. Scanning electron photographs (SEM, JSM 6360 LV, Joel Ltd., Tokyo, Japan) were taken with an electron beam of an accelerating voltage of 10 kV using secondary electron image (SEI) as the detector at 50 KX magnifications.
Sample was analyzed between the interval 5–50° 2θ with scanning speed of 2°/min using X-ray diffraction system (Philips Analytic X-Ray – PW 1729; Philips, Almelo, The Netherlands). The diffraction pattern was measured with generator tension (voltage) and generator current of 40 kV and 30 mA respectively.
Drug releases from cocrystals were determined using USP type II (paddle) dissolution method. Atorvastatin and its cocrystal formulations equivalent weight 100 mg were placed in 900 ml/ 0.05 M phosphate buffer pH 6.8, 37 ± 0.5 °C and stirred at 75 rpm. At definite time intervals, aliquot of the samples were withdrawn, filtered through Millipore filter (0.45 µm) and analyzed UV spectrophotometrically at 246 nm. In order to maintain sink condition, equal quantity of fresh dissolution medium maintained at the same temperature was added after each sampling.
Wistar albino rats of either sex weighing 190 ± 20 g were obtained from animal house attached to the institute. Animals were exposed to natural day and night cycles with ideal laboratory condition in terms of ambient temperature (22 ± 2 °C) and humidity (50–60%). They were fed with rat pellet feed and tap water given ad libitum. All animals were maintained according to CPCSEA guidance (439/PO/RE/S/01/CPCSEA). The experiments were carried out after obtaining the permission of Institutional Animal Ethics Committee (Approval number; IAEC/04/2016/17/PG).
Hyperlipidemic rats were prepared by feeing of high fat diet composed normal pellet diet 40 gm%, Animal fat 25 gm%, Coconut oil 6 gm% Fructose 10 gm%, casein 6 gm%, Egg protein 12 gm%, Minerals and vitamins 0.5 gm%, NaCl 0.5 gm%) for 8 weeks.
Group I: Normal rats
Hyperlipidemic rats were dividing into following groups
Group II: High fat diet feeding rats
Group III: Unprocessed atorvastatin 7.5 mg/kg orally
Group IV: Unprocessed atorvastatin 75 mg/kg orally.
Group V: Atorvastatin ascorbic acid cocrystals 7.5 mg/kg orally.
Group VI: Atorvastatin ascorbic acid cocrystals 75 mg/kg orally.
Atorvastatin and atorvastatin ascorbic acid co-crystals were administered into rats in the form of an aqueous suspension in 0.5% sodium carboxymethylcellulose (Na-CMC). Blood was collected from retro orbital plexus at 0 day, 1st , 2nd , 4th and 8th week, serum was separated, subjected for estimation of serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), triglycerides, total cholesterol. At the end of 8th weeks of treatment rats were euthanized using CO2 chamber, isolate the liver, and then homogenate, supernatant was used for estimation of reduced glutathione.
The data generated during the study were subjected to Dunnet’s test, data to assess the statistical significance. ‘p’; value less than 0.05 were considered as statistically significant. Significant at **p < 0.01; *p < 0.05, a: Comparison between ATV 7.5 mg/kg orally vs AAC 7.5 mg/kg orally; b: Comparison between ATV 75 mg/kg orally vs AAC 75 mg/kg orally.
Atorvastatin ascorbic acid cocrystals are developed with yield of 97%, drug content range was 96±1.5 w/w to 99±1.21w/w.
Unprocessed atorvastatin shows an O – H stretching vibration of 3748.44 cm-1, which is reduced to 3732.69 cm-1, indicating hydrogen bonding of ascorbic acid carbonyl oxygen to the atorvastatin O-H group. Amide group of atorvastatin exhibits carbonyl stretch at 1673.04 cm-1 which is reduced to 1650.41 confirms the hydrogen bonding between atorvastatin and ascorbic acid (Fig.
Ascorbic acid co-crystal atorvastatin was shown to have a higher melting point of 267.43 °C when compared to individual atorvastatin (163.46 °C) and Ascorbic acid (195.92 °C). This confirms the co-crystal formation and physical interaction of atorvastatin with Ascorbic acid through hydrogen bonding, which increased the energy value in crystals compared to atorvastatin (Fig.
Atorvastatin appeared in large and irregular formed particles, while ascorbic acid was granular. Atorvastatin and ascorbic acid cocrystals showed fine particles with uniform dimensions and SEM results showed a reduction in particle size to 221 nm (Fig.
Cocrystal is a supramolecular synthon which is formed by the stoichiometric mixing of atorvastatin with ascorbic acid. The interaction of one molecule with other leads to formation of new crystal lattice which is confirmed by comparing standard XRD values of Atorvastatin, ascorbic acid 21.44, 35.38, respectively, cocrystal exhibited 18.48 this is due to hydrogen bonding the lattice energy has decreased to significant level. This confirms the formation of atorvastatin: ascorbic acid co-crystal formation (Fig.
The release of atorvastatin was 1.60 fold enhanced by cocrystals in comparison with unprocessed atorvastatin (Fig.
Unprocessed ATV (75 mg/kg, p.o) treated high fat diet rats serum SGPT, SGOT levels were significantly (*P < 0.05) increased 52.8%, 51.09%, respectively compared to untreated rats. AAC (75 mg/kg, p.o) treated high fat diet rats serum SGPT, SGOT levels were decreased significantly by 20.9% and 6.79% respectively, compared ATV treated high fat diet rats (Figs
Unprocessed ATV (75 mg / kg orally) treated high fat diet rats with total serum cholesterol and triglycerides (**p < 0.01) decreased 16.3%, 27.8% compared to untreated rats (Figs
Unprocessed ATV (75 mg/kg. orally.) treated rat hepatic reduced GSH levels are significantly (p < 0.001***) decreased compared to hyperlipidemic as well as normal rats. However, administration of AAC had the opposite effect, where it significant (p < 0.05*) increased hepatic reduced GSH activities nearly to that of control (Fig.
Phase solubility study of atorvastatin with ascorbic acid at different molar ratios was able to produce co-crystalline solids with enhanced dissolution rate compared with the parent drug. Atorvastatin should be mixed with ascorbic acid at a molar ratio of 1:1 for optimum cocrystallization. Co-crystallization induced dissolution enhancement was able to improve the efficacy of the drug as expressed by reduction in lipid profile and improve the safety of atorvastatin on hyperlipidemic rats compared to the unprocessed atorvastatin.
The authors declare no conflicts of interest
Authors thankful to Shri Vishnu College of Pharmacy, Bhimavaram, India for providing needed lab facilities to carried out research work. Authors are also thankful to Osmania University, Hyderabad for supporting SEM and PXRD characterization of samples.