Priti Mehta

Concurrent Estimation of Amlodipine Besylate, Hydrochlorothiazide and Valsartan by RP-HPLC, HPTLC and UV–Spectrophotometry

Accurate, sensitive and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC), high-performance thin-layer chromatography (HPTLC) and ultraviolet (UV) spectrophopometric methods were developed for the concurrent estimation of amlodipine besylate (AMLO), hydrochlorothiazide (HCTZ) and valsartan (VALS) in bulk and combined tablet dosage forms. For the RP-HPLC method, separation was achieved on a C18 column using potassium dihydrogen orthophosphate buffer (50 mM, pH 3.7) with 0.2% triethylamine as the modifier and acetonitrile in the ratio of 56:44 (v/v) as the mobile phase. Quantification was achieved using a photodiode array detector at 232 nm over a concentration range of 2-25 µg/mL for AMLO, 5-45 µg/mL for HCTZ and 20-150 µg/mL for VALS. For the HPTLC method, the drugs were separated by using ethyl acetate-methanol-toluene-ammonia (7.5:3:2:0.8, v/v/v/v) as the mobile phase. Quantification was achieved using UV detection at 242 nm over a concentration range of 100-600 ng/spot for AMLO, 150-900 ng/spot for HCTZ and 1,200-3,200 ng/spot for VALS. The UV-spectrophotometric simultaneous equation method was based on the measurement of absorbance at three wavelengths; i.e., at 237.6 nm (λmax of AMLO), 270.2 nm (λmax of HCTZ) and 249.2 nm (λmax of VALS) in methanol. Quantification was achieved over the concentration range of 2-20 µg/mL for AMLO, 5-25 µg/mL HCTZ and 10-50 µg/mL for VALS. All methods were validated according to International Conference on Harmonization guidelines and successfully applied to marketed pharmaceutical formulations. Additionally, the three methods were compared statistically by an analysis of variance test, which revealed no significant difference between the proposed methods with respect to accuracy and precision.

Simultaneous RP-HPTLC method for determination of levodopa, carbidopa, and entacapone in combined tablet dosage form

A simple, rapid, specific, and accurate reverse-phase high-performance thin-layer chromatography (RP-HPTLC) method was developed and validated for simultaneous quantification of levodopa, carbidopa, and entacapone in their combined dosage form. Due to the structural similarity between levodopa and carbidopa, and vast difference in their polarity with that of entacapone, it is very challenging to carry out the simultaneous estimation of all three drugs together. In the developed method, chromatography was performed on TLC plates with precoated silica gel 60 RP-18 F254 using acetonitrile-n-butanol-water-triethylamine (0.5:9.5:1:0.001, v/v/v/v), pH adjusted to 3.6 with o-phosphoric acid, as the mobile phase. Densitometric evaluation was performed at 282 nm. The RF values were 0.46, 0.64, and 0.87 for levodopa, carbidopa, and entacapone, respectively. The polynomial regression data for the calibration plots showed good linear relationship in the concentration range 300–1500 ng per spot for levodopa, 200–1000 ng per spot for carbidopa, and 200–2000 ng per spot for entacapone. The suitability of this HPTLC method for quantitative determination of drugs was proved by validation in accordance with the requirements of the International Conference on Harmonization (ICH) guidelines (Q2B).

Current Approaches for in vitro Drug Release Study of Long Acting Parenteral Formulations

Long acting parenteral formulations are preferred over conventional formulations for the treatment of chronic diseases. Prevalence of such diseases provoked the interest of researchers and pharmaceutical industries in the development of long acting parenteral formulations. The regulatory guidelines and pharmacopoeia have remained silent on dissolution methods for long acting parenteral formulations due to their diverse nature. The lack of compendial method for dissolution testing increases the duration of approval process for long acting parenteral formulations. This article reviews various dissolution methods used to study in vitro drug release profile of long acting parenteral formulations. Compendial as well as noncompendial methods, such as- rotating dialysis cell, dialysis tube, rotating bottle, shaking flask, single drop, inverted cup and incubation, are used by researchers for drug release profile of long acting parenteral formulations. This review article also highlights the advantages and disadvantages of reported dissolution methods along with the suitability of these methods for particular type of long acting formulation. The compiled work will help the researchers in designing the biorelevant dissolution method and expedite the development of long acting parenteral formulations.

Development and Validation of Packed Column Supercritical Fluid Chromatographic Technique for Quantification of Chlorzoxazone, Paracetamol and Aceclofenac in their Individual and Combined Dosage Forms

A reproducible, rapid and sensitive method has been developed for the assay of chlorzoxazone (CHL), paracetamol (PCM) and aceclofenac (ACE) in their combined solid dosage forms using packed-column supercritical fluid chromatography (SFC). The analytes were resolved by elution with supercritical carbon dioxide doped with 15% v/v methanol as the modifier on an ACE 5 Phenyl column (150 × 4.6 mm, 5 µm). The detection was carried out at 215 nm using a UV-Visible detector. The densities and polarities of the mobile phase were optimized from the effects of pressure, temperature and modifier concentration on chromatographic parameters like retention time, retention factor, resolution, asymmetry and theoretical plates. Modifier concentration proved to be the most effective means for changing both retention and selectivity. The developed method was validated as per International Conference on Harmonization guidelines. The developed SFC method was compared with a reported high-performance liquid chromatography method for the estimation of CHL, PCM and ACE using Student t-test. With respect to the speed and use of organic solvents, SFC was found to be superior and eco-friendly. The developed SFC method was successfully used for the assay of different marketed formulations containing CHL, PCM and ACE individually and in combination.

Spectrofluorimetric estimation of salbutamol sulphate in different dosage forms by formation of inclusion complex with β-cyclodextrin

A simple, precise, reproducible and accurate spectrofluorimetric method for estimation of Salbutamol sulphate (SAL) in bulk drug and various dosage forms has been developed. This method is based on formation of inclusion complex of SAL in β-cyclodextrin (BCD) which gives fluorescence at excitation wavelength of 279.6 nm and emission wavelength of 609.8 nm in water. Formation of inclusion complex of drug with BCD enhances fluorescence intensity of drug leads to increased sensitivity. The developed method was validated according to ICH guidelines with respect to accuracy, precision, linearity, limit of detection, limit of quantification. Linearity was observed in the range of 4-20 μg/ml with correlation coefficient of 0.9982. The simplicity of the method permitted rapid analysis suitable for routine control. The developed method was successfully applied for the estimation of SAL in different marketed dosage forms like tablets, syrup and aerosol.

Impact of space environment on stability of medicines: Challenges and prospects

&NA; To upkeep health of astronauts in a unique, isolated, and extreme environment of space is the primary goal for a successful space mission, hence, safe and efficacious medications are essential for the wellness of astronauts. Space medication has been challenged with problems related to efficacy. Along with altered physiology, one of the possible reasons could be instability of space medications in the presence of harsh spaceflight environmental conditions. Altered physical and chemical stability can result in reduced potency which can result in reduced efficacy. Right now, medicines from the International Space Station are replaced before their expiration. But, for longer duration missions to Mars or any other asteroid, there will not be any chance of replacement of medicines. Hence, it is desired that medicines maintain the shelf‐life throughout the space mission. Stability of medicines used for short term or long term space missions cannot be judged by drug stability guidelines based on terrestrial environmental factors. Unique environmental conditions related to spaceflight include microgravity, excessive vibration, hard vacuum, humidity variation, temperature differences and excessive radiation, which may cause instability of medicines. This write‐up provides a review of the problem and countermeasure approaches for pharmaceuticals exposed to the space environment. The first part of the article discusses thought processes behind outlining of International Conference on Harmonization drug stability guidelines, Q1A (R2) and Q1B, and its acceptance limits for accelerated stability study. The second part of the article describes the difference in the radiation environment of deep space compared to radiation environment inside the space shuttle based on penetration power of different types of radiation. In the third part of the article, various promising approaches are listed which can be used for assurance of space medicine stability. One of the approaches is the use of ground‐based space simulation analogues and statistical treatment to data to calculate failure rate of drugs and probabilistic risk assessment. Another approach is to innovate storage and packaging technology using radiation harden polymer or using cryogenic temperatures. HighlightsComplex spaceflight environment can lead to unexpected alteration in efficacy and stability of space medicines.The knowledge regarding space radiation environment and its penetration inside the spacecraft is essential to understand its effect on medicines.Simulation of spaceflight variables on ground can be used as accelerated stability study of space medicine.Various promising strategies including novel packaging materials, cryogenic storage and advanced technology for formulation development can serve the purpose of extension of space medicines stability.

Comprehensive Assessment of Degradation Behavior of Aspirin and Atorvastatin Singly and in Combination by Using a Validated RP-HPLC Method.

A fixed-dose combination of atorvastatin and aspirin is widely used for the treatment of myocardial infarction. The present work describes a comprehensive study of the stress degradation behavior of atorvastatin and aspirin alone as well as in combination of 1:1 and 1:7.5 ratios, respectively, as per ICH guidelines. The degradation products of aspirin as well as atorvastatin were successfully separated by a developed simple, selective, and precise stability-indicating reversed-phase HPLC method. Chromatographic separation was achieved on the Phenomenex Luna analytical column, 150 mm × 4.6 mm, 5μm. The mobile phase consisted of 0.1% glacial acetic acid in water and acetonitrile in the ratio of 50:50 v/v at a flow rate of 1.0 ml/min. UV detection was performed at 246 nm. The extent of degradation was significantly influenced when both of the drugs were present in combination. Stress degradation behavior of atorvastatin was highly influenced by aspirin under acid hydrolysis, thermal degradation, and oxidative stress conditions. Similarly, the stress degradation behavior of aspirin was affected by atorvastatin especially under neutral hydrolysis, thermal degradation, and oxidative stress conditions. Additionally, the combination ratio of aspirin and atorvastatin also influenced the percentage degradation of each other. A mixture of aspirin and atorvastatin was also analyzed after a one-month stability study at 40 °C and 75% RH. All the results indicate chemical incompatibility of both aspirin and atorvastatin if present in combination.

Stability-indicating HPTLC method for determination of milnacipran hydrochloride in pharmaceutical formulations

A simple, specific, precise and accurate stability-indicating assay method using high performance thin-layer chromatography (HPTLC) is described for estimation of Milnacipran hydrochloride (MIL) in bulk drug and in pharmaceutical formulations. The separations were achieved on prepared TLC plates precoated with silica gel 60 F254. The mobile phase developed and optimized for bringing out the separation involves chloroform-methanol-ammonia in the ratio of 6.4:2.5:0.2 v/v/v. The densitometric scanning wavelength selected was 220 nm. The compact bands of MIL were obtained at RF value of 0.45 ± 0.02. The method developed was able to separate peaks of all the degradation products formed in ICH-prescribed stress conditions with sufficient difference in their RF values. The developed method was validated for linearity and range, specificity, precision, accuracy and robustness, and the results were found to be within acceptance criteria. The reliability of the method was evaluated when it was applied for the estimation of MIL in pharmaceutical capsule formulation, and assay results gave good recovery when statistically compared with the reversed-phase high-performance liquid chromatography (RP-HPLC) method.

Development and validation of RP-HPLC, HPTLC and UV-visible spectrophotometric methods for simultaneous estimation of alprazolam and propranolol hydrochloride in their combined dosage form

Three accurate, sensitive and reproducible methods are described for the quantitative determination of alprazolam (ALP) and propranolol hydrochloride (PNL) in their combined dosage form. The first method involves an RP-HPLC separation on the C18 column using acetonitrile-25 mM ammonium acetate buffer and 0.2% triethylamine (pH of buffer adjusted to 4 with glacial acetic acid) in the ratio of 35: 65 (v/v) as mobile phase. Symmetrical peaks with good separation, ALP at 9.3 min and PNL at 3.5 min, were achieved. Quantification was done with photo diode array detection at 255 nm over the concentration ranges of 0.5–50 and 10–250 μg/mL for ALP and PNL, respectively. The second method is based on the separation of drugs by HPTLC using chloroform-methanol-ammonia 7: 0.8: 0.1 (v/v/v) as mobile phase. Quantification was achieved using UV detection at 248 nm over the concentration range of 100–600 ng/spot and 5–30 μg/spot for ALP and PNL, respectively. The third method involves dual wavelength UV-visible spectrophotometric method. It is based on the determination of PNL at 319.4 nm using its absorptivity value and ALP at 258.2 nm after deduction of absorbance due to PNL. Quantification was achieved over the concentration range of 1–40 and 80–200 μg/mL for ALP and PNL, respectively. All methods were validated according to ICH guidelines and successively applied to marketed pharmaceutical formulation, and the results of all three methods were compared statistically as well. No interference from the tablet excipients was found.

Validated high-performance thin-layer chromatographic method for the quantification of betulinic acid from two Indian plants of the species Dillenia and Ziziphus

Betulinic acid (BA), a potent anticancer agent, occurs in more than 50 plant species worldwide, out of which Dillenia and Ziziphus species are found in Gujarat, India. The presented research work was aimed at the development of a single validated high-performance thin-layer chromatographic (HPTLC) method which can quantify BA from different plant species and thereof from different chemical environments. The analysis was performed on a thin-layer chromatographic (TLC) precoated silica gel 60 F254 plate using a mobile phase of toluene-chloroform-ethanol (4:4:1, v / v / v) and after derivatization with anisaldehyde sulfuric acid reagent showed magenta color spot at RF 0.71. Densitometric evaluation of BA was carried out at 525 nm. The suitability of this HPTLC method for quantitative determination of BA was proved by validation in accordance with the requirements of the International Conference on Harmonization (ICH) guidelines. The occurrence of BA is more frequent in bark or stem as compared to leaves. The content of BA was found to be the highest, 0.43%, in Dillenia indica bark.