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author:(wilayat Sayeed)
1.  Development and Validation of a HPLC Method for Dissolution and Stability Assay of Liquid-Filled Cyclosporine Capsule Drug Products 
AAPS PharmSciTech  2013;14(3):959-967.
To assay the dissolution samples of a drug product from several sources, a simple but broadly applicable analytical method is always desired. For the liquid-filled cyclosporine capsules, while analyzing the dissolution samples, the current compendial and literature HPLC methods have been found to be inadequate to provide satisfactory separation of the drug and the excipient peaks. Accordingly, a suitable isocratic reverse-phase HPLC method was developed for the analysis of dissolution samples of liquid-filled cyclosporine capsules. The method successfully separated the cyclosporine peak from the interfering chromatographic peaks of the excipients. The method was validated according to the ICH and FDA guidelines. Specificity, selectivity, linearity, accuracy, precision, and robustness were established over 3 days as part of method validation. Additionally, the degradation kinetics of cyclosporine in dissolution media was determined. Cyclosporine degradation followed a zero-order kinetics in the dissolution media with the respective rate constants of −3.5, −1.5, and −0.3%/h at 37°C, 25°C, and 10°C.
doi:10.1208/s12249-013-9983-8
PMCID: PMC3755155  PMID: 23761263
cyclosporine; degradation; dissolution; HPLC; liquid-filled capsules
2.  Improvement of Physicochemical Properties of an Antiepileptic Drug by Salt Engineering 
AAPS PharmSciTech  2012;13(3):793-801.
The focus of the present investigation was to evaluate the feasibility of using cyclamic salt of lamotrigine in order to improve its solubility and intrinsic dissolution rate (IDR). The salt was prepared by solution crystallization method and characterized chemically by fourier transform infrared spectroscopy (FTIR), proton (1H) and carbon (13C) nuclear magnetic resonance (liquid and solid, NMR) spectroscopy, physically by powder X-ray diffraction (PXRD), thermally by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), physicochemically for solubility, IDR, solution and solid-state stability, and polymorphism by solution recrystallization and slurry conversion studies. The FTIR, NMR, PXRD, DSC, and TGA spectra and thermograms indicated the salt formation. The salt formation increased lamotrigine solubility by 19-fold and IDR by 4.9-fold in water. The solution and solid-state stability were similar to parent molecule and were resistant to polymorphic transformation. In conclusion, cyclamic salt of lamotrigine provides another potential avenue for the pharmaceutical development of lamotrigine with improved physicochemical properties especially for pediatric population. It is also possible that appropriate dosage forms can be formulated with much lower drug amount and better safety profile than existing products.
doi:10.1208/s12249-012-9800-9
PMCID: PMC3429685  PMID: 22588676
cyclamic acid; dissolution; lamotrigine; salt; solubility
3.  Analysis of Bead Sizes for MR Capsules Labeled for Sprinkle 
AAPS PharmSciTech  2010;11(4):1508-1510.
The bead sizes used in approved modified release capsules labeled for sprinkling on food was investigated to generate bead size guidelines for generic products labeled for sprinkling. The conclusions from a survey of FDA databases were corroborated with experimental data obtained by measuring the bead sizes of several reference-listed drugs on the market labeled for administration by sprinkling on food. The experimental data show that majority of the marketed products were found to have bead sizes of less than 1,500 μm (1.5 mm). Based on this information, a bead size of less than 1,500 μm should generally be considered acceptable for use in generic products labeled for sprinkling.
doi:10.1208/s12249-010-9529-2
PMCID: PMC3011084  PMID: 20936439
bead size; generic drugs; modified-release capsules; quality target product profile; sprinkle
4.  Tablet Splitting of a Narrow Therapeutic Index Drug: A Case with Levothyroxine Sodium 
AAPS PharmSciTech  2010;11(3):1359-1367.
Levothyroxine is a narrow therapeutic index, and to avoid adverse effect associated with under or excessive dosage, the dose response is carefully titrated. The tablets are marketed with a score providing an option to split. However, there are no systematic studies evaluating the effect of splitting on dose accuracy, and current study was undertaken to evaluate effects of splitting and potential causes for uniformity failures by measuring assay and content uniformity in whole and split tablets. Stability was evaluated by assaying drug for a period of 8 weeks. Effect of formulation factors on splittability was evaluated by a systematic investigation of formulation factors by preparing levothyroxine tablets in house by varying the type of excipients (binder, diluent, disintegrant, glidant) or by varying the processing factors (granulating liquid, mixing type, compression pressure). The tablets were analyzed using novel analytical tool such as near infrared chemical imaging to visualize the distribution of levothyroxine. Assay was not significantly different for whole versus split tablets irrespective of method of splitting (hand or splitter), and splitting also had no measurable impact on the stability. Split tablets either by hand or splitter showed higher rate of content uniformity failures as compared to whole tablets. Tablet splitter produced more fragmentation and, hence, more content uniformity and friability failures. Chemical imaging data revealed that the distribution of levothyroxine was heterogeneous and was dependent on type of binder and the process used in the manufacture of tablets. Splitting such tablets could prove detrimental if sub- or super-potency becomes an issue.
doi:10.1208/s12249-010-9515-8
PMCID: PMC2974142  PMID: 20740332
content uniformity; hand splitting; levothyroxine sodium; narrow therapeutic index; splitter; tablet splitting
5.  Influence of Formulation and Processing Factors on Stability of Levothyroxine Sodium Pentahydrate 
AAPS PharmSciTech  2010;11(2):818-825.
Stability of formulations over shelf-life is critical for having a quality product. Choice of excipients, manufacturing process, storage conditions, and packaging can either mitigate or enhance the degradation of the active pharmaceutical ingredient (API), affecting potency and/or stability. The purpose was to investigate the influence of processing and formulation factors on stability of levothyroxine (API). The API was stored at long-term (25°C/60%RH), accelerated (40°C/75%RH), and low-humidity (25°C/0%RH and 40°C/0%RH) conditions for 28 days. Effect of moisture loss was evaluated by drying it (room temperature, N2) and placed at 25°C/0%RH and 40°C/0%RH. The API was incubated with various excipients (based on package insert of marketed tablets) in either 1:1, 1:10, or 1:100 ratios with 5% moisture at 60°C. Commonly used ratios for excipients were used. The equilibrium sorption data was collected on the API and excipients. The API was stable in solid state for the study duration under all conditions for both forms (potency between 90% and 110%). Excipients effect on stability varied and crospovidone, povidone, and sodium laurel sulfate (SLS) caused significant API degradation where deiodination and deamination occurred. Moisture sorption values were different across excipients. Crospovidone and povidone were hygroscopic whereas SLS showed deliquescence at high RH. The transient formulation procedures where temperature might go up or humidity might go down would not have major impact on the API stability. Excipients influence stability and if possible, those three should either be avoided or used in minimum quantity which could provide more stable tablet formulations with minimum potency loss throughout its shelf-life.
doi:10.1208/s12249-010-9434-8
PMCID: PMC2902299  PMID: 20454876
excipients; formulation; levothyroxine sodium pentahydrate; moisture sorption; stability
6.  Difference in the Lubrication Efficiency of Bovine and Vegetable-Derived Magnesium Stearate During Tabletting 
AAPS PharmSciTech  2009;10(2):500-504.
The purpose of this work was to evaluate and compare the functionality of bovine fatty acids-derived (MgSt-B) and vegetable fatty acids-derived (MgSt-V) magnesium stearate powders when used for the lubrication of granules prepared by high-shear (HSG) and fluid bed (FBG) wet granulation methods. The work included evaluation of tablet compression and ejection forces during tabletting and dissolution testing of the compressed tablets. Granules prepared by both granulation methods required significantly lower ejection force (p < 0.01) when lubricated with the MgSt-V powder as compared to those lubricated with the MgSt-B powder. Granules prepared by the HSG method and lubricated with the MgSt-V powder also required significantly lower compression force (p < 0.01) to produce tablets of similar weight and hardness as compared to those lubricated with the MgSt-B powder. The dissolution profiles were not affected by these differences and were the same for tablets prepared by same granulation method and lubricated with either magnesium stearate powder. The results indicate significant differences (p < 0.01) between lubrication efficiency of the MgSt-B and the MgSt-V powders and emphasize the importance of functionality testing of the MgSt powders to understand the impact of these differences.
doi:10.1208/s12249-009-9229-y
PMCID: PMC2690792  PMID: 19390976
characterization; fluid bed granulation; functionality testing; high-shear granulation; lubricant efficiency; magnesium stearate
7.  Disintegration of Highly Soluble Immediate Release Tablets: A Surrogate for Dissolution 
AAPS PharmSciTech  2009;10(2):495-499.
The purpose of the work was to investigate correlation between disintegration and dissolution for immediate release tablets containing a high solubility drug and to identify formulations where disintegration test, instead of the dissolution test, may be used as the acceptance criteria based on International Conference on Harmonization Q6A guidelines. A statistical design of experiments was used to study the effect of filler, binder, disintegrating agent, and tablet hardness on the disintegration and dissolution of verapamil hydrochloride tablets. All formulation variables, i.e., filler, binder, and disintegrating agent, were found to influence tablet dissolution and disintegration, with the filler and disintegrating agent exerting the most significant influence. Slower dissolution was observed with increasing disintegration time when either the filler or the disintegrating agent was kept constant. However, no direct corelationship was observed between the disintegration and dissolution across all formulations due to the interactions between different formulation components. Although all tablets containing sodium carboxymethyl cellulose as the disintegrating agent, disintegrated in less than 3 min, half of them failed to meet the US Pharmacopeia 30 dissolution criteria for the verapamil hydrochloride tablets highlighting the dependence of dissolution process on the formulation components other than the disintegrating agent. The results identified only one formulation as suitable for using the disintegration test, instead of the dissolution test, as drug product acceptance criteria and highlight the need for systematic studies before using the disintegration test, instead of the dissolution test as the drug acceptance criteria.
doi:10.1208/s12249-009-9227-0
PMCID: PMC2690790  PMID: 19387843
disintegration test; dissolution test; ICH Q6A; specification

Results 1-7 (7)