Bioequivalency of doxycycline products.

The bioavailability of three different brands and three different dosage forms of doxycycline was studied in normal subjects. Single doses, equivalent to 200 mg of doxycycline, were administered to six subjects in a crossover design as the innovator's intravenous solution given orally (Treatment A), the innovator's capsule product (Treatment B), a noninnovator's capsule product (Treatment C), the innovator's oral suspension product (Treatment D), and a second noninnovator's capsule product (Treatment E). All dosage forms contained doxycycline as the hyclate, except the suspension which contained the nonhyclate form. Serum levels were determined periodically over 48 hr, and cumulative urinary excretion was measured concurrently over a 120-hr collection period. No statistically significant differences were observed in any in vivo indicator of bioequivalence when the three capsule products were compared. Consequently, they were judged to be bioequivalent. When these capsule products were compared to the oral solution, no statistically significant differences were observed. However, when the capsules and the suspension were compared, statistically significant differences were found in the rate of absorption. In vitro dissolution tests were also conducted on the three brands of capsules, and times required to achieve 50% dissolution showed rank-order correlation with corresponding absorption rate constants.     

Densitometric determination of conjugated oestrogens in the raw material and in pharmaceutical preparations

A densitometric method for determination of complex mixtures of conjugated oestrogens in raw material and tablets was developed. The proposed procedure comprised hydrolysis of sodium sulphate esters of oestrone, equilin, 17 alpha-oestradiol, equilenin, 17 alpha-dihydroequilin and 17 alpha-dihydroequilenin, the chloroform extraction of free oestrogens and methyltestosterone (internal standard) and separation on TLC plates using chloroform-cyclohexane-dioxane-triethylamine (4.5:4.1:0.6, v/v) as the solvent for development. Quantitative assay was achieved by direct scanning of the oestrogen spots at 280 nm. The proposed method is simple, rapid, reproducible and adequate to control the content of conjugated oestrogens in the raw material and in pharmaceutical preparations.     

Comparative in vitro dissolution study of carbamazepine immediate-release products using the USP paddles method and the flow-through cell system

Dissolution profiles of four carbamazepine immediate-release generic products (200 mg tablets) and the reference product Tegretol® were evaluated using the USP paddles method and an alternative method with the flow-through cell system, USP Apparatus 4. Under official conditions all products met the Q specification, dissolution profiles of generic products were similar to the dissolution profile of the reference product (f₂ > 50) and model-independent parameters showed non significant differences to the reference product except mean dissolution time for product A (p < 0.05). On the other hand, when the flow-through cell system was used, none of the products met the pharmacopeial specification at 15 min and product A did not reach dissolution criteria at 60 min, dissolution profiles of all generic products were not similar to the reference product profile (f₂ < 50) and all model-independent parameters showed significant differences compared to the reference product (p < 0.05). Weibull’s model was more useful for adjusting the dissolution data of all products in both USP apparatuses and Td values showed significant differences compared to the reference product (p < 0.05) when USP Apparatus 4 was used. These results indicate that the proposed method, using the flow-through cell system, is more discriminative in evaluating both, rate and extent of carbamazepine dissolution process from immediate-release generic products.     

Marketplace Analysis of Conjugated Estrogens: Determining the Consistently Present Steroidal Content with LC-MS

Conjugated estrogens purified from pregnant mares urine has been used as estrogen hormone replacement therapy since 1942. Previously, methods were proposed to identify and quantify the components of this complex mixture but ultimately were withdrawn due to incomplete characterization of the product and difficulties in transferring the method between laboratories. The aim of the current study is to develop a LC method that can reliably detect multiple steroidal components in conjugated estrogen tablets and measure their relative amount. The method developed was optimized for UHPLC columns, and the elution profile was analyzed using high-resolution mass spectrometry. A total of 60 steroidal components were identified using their exact m/z, product ion spectra of known, and predicted conjugated estrogen structures. These components were consistently present in 23 lots of Premarin tablets spanning two production years. The ten conjugated estrogens identified in the USP monograph and other additional estrogens reported elsewhere are among the 60 steroidal components reported here. The LC-MS method was tested in different laboratories using multiple samples, and the obtained results were reproducible among laboratories.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-015-9805-x) contains supplementary material, which is available to authorized users.KEY WORDS: conjugated estrogens, mass spectrometry, steroidal content     

Bioequivalence study of nalidixic acid tablets: In vitro–in vivo correlation

The USP dissolution test was used to select seven products with a wide range of dissolution characteristics for in vivo examination. The bioequivalence of seven (500 mg) products was evaluated in two crossover urinary excretion experiments. In each study three products were compared with the innovator product (Negram-Winthrop-Breon) in 12 subjects according to a 4 × 4 latin square design. Significantly different, lower bioavailability was observed in two products in relation to that of the innovator product. Linear in vitro–in vivo correlations were found between the cumulative amount excreted at 24 h and the log of the amount dissolved at 30 min and between log of the cumulative amount excreted up to 24 h and the log of the amount dissolved at 45 min.     

Steady-state urinary excretion method for determining bioequivalence of conjugated estrogen products.

The steady-state excretion of conjugated estrogens in the urine of postmenopausal women dosed with conjugated estrogens tablets was studied using a modification of a previously published method. The procedure was used to quantitate the estrogens both before and during conjugated estrogens replacement therapy. The method, which is relatively specific, involves enzyme hydrolysis of urine samples a number of classical extraction and purification steps, and analysis of the silylated estrogens on a 2.7-m, 1.7% diethylene glycol succinate column using flame-ionization detection. The results indicate that steady-state urinary estrogen excretion levels were obtained within 17 days of dosing. Furthermore, the urinary estrogen excretion profile was significantly different from the composition of the estrogens in the dosage form.     

Pharmaceutical equivalency of locally and regionally manufactured generic pharmaceutical products in UAE

Generic drugs or generic medicines are pharmaceutical products manufactured to be equivalent to the brand/innovator drug products. They represent the majority of worldwide prescribed medicines; therefore, their quality is critical to maximize patients’ therapeutic outcomes. This study aimed to evaluate the pharmaceutical equivalency of locally and regionally manufactured generic pharmaceutical products being sold in the United Arab Emirates (UAE) market to enhance public confidence, promote their utilization, and reduce treatment costs. Three drugs (tadalafil, rosuvastatin, and acetaminophen) from three different pharmacological classes were selected from the UAE market as representatives for generic drugs. At least two generic products for each locally (L) and regionally (R) manufactured generic were evaluated according to the USP criteria in comparison to the brand (B) comparator product. All comparative tests were performed before storage and 3 and 6 months after storage during the accelerated stability study performed under the conditions for climatic zone IV (40 °C ± 2 °C /75% RH ± 5% RH). Although results were statistically different from the comparators using ANOVA and Tukey’s Kremer post hoc tests, all tests were within the USP acceptance limits, except one, for friability, disintegration, content uniformity, and dissolution. Significant changes were observed following their storage over 6 months during accelerated stability studies, however, without failing the USP limits. Only one locally manufactured acetaminophen generic failed the USP dissolution tests before and after its storage and failed the disintegration test following its storage under accelerated conditions for zone IV. In conclusion, the majority of the locally and regionally manufactured generic products being sold in the UAE market were of good quality and performed similarly to their comparators. However, a continuous independent quality evaluation for the marketed generic drugs is essential to enhance public confidence.     

Generic tolbutamide tablet dissolution: intralot and interlot variation

Dissolution profiles for 62 lots of tolbutamide tablets from six manufacturers have been characterized using the USP paddle-stirrer apparatus. Results of paddle-stirrer dissolution for percent drug dissolved at 10, 20, and 30 min correlated well (r2 = 0.7444) with results from the USP rotating-basket test for 39 lots of tolbutamide. Interlot and intralot variability in tolbutamide dissolution was highly dependent on the manufacturer. For one product, the intralot range (for six paddle-stirred tablets) of percent drug dissolved after 30 min was 50-68% while the maximum interlot range for mean dissolution was 58-104%. One lot failed to meet both the rotating-basket and the paddle-stirrer dissolution specifications. Tablet response to aging at 60, 75, and 98% relative humidity over time was also highly manufacturer specific. The innovator's product repeatedly dissolved well when fresh or aged at all humidities. Dissolution from some generic tablets was dramatically depressed by humidity aging, even after only 3 d. Pretreatment of tablets with simulated gastric fluid modified the dissolution profile of one poorly dissolving lot of tablets. Results indicate that manufacturing quality control is highly variable among tolbutamide tablets.     

Fluorodensitometric determination of conjugated estrogens in raw material and in pharmaceutical preparations

A simple, rapid and reproducible fluorodensitometric method for the determination of conjugated estrogens has been developed. The proposed procedure includes the following steps: extraction, hydrolysis of sodium sulphate esters of estrone, equilin, equilenin and their 17--hydroxy derivatives, separation of the liberated 3-phenolic steroids and in situ measurement of fluorescence. The fluorescence emission was measured after spraying the spots of estrone and estradiol with 2,4-dinitrophenylhydrazine in sulphuric acid—ethanol medium and equilin and 17--dihydroequilin with phosphoric acid and sodium hydroxide solution, respectively. Equilenin and 17--dihydroequilenin were determined by measuring the native fluorescence. The method applied to the determination of raw material and tablets provided results which agreed well with the stated content and the requirements of USP XXI for conjugated estrogens.     

Preliminary observations on dissolution and bioavailability of triamterene–hydrochlorothiazide combination products

The dissolution profiles of two brands of triamterene–hydrocholorthiazide (TRM–HCT) combination tablets and two brands of TRM–HCT combination capsules were studied using the USP paddle method at 100 rev min^?1 in acid medium (0·1 N). The tablets represent two products marketed in Germany, whereas the capsules represent the approved innovator's product and an unapproved generic product. The tablets dissolved almost 100 per cent in 15 min whereas the capsules dissolved less than 25 per cent in 60 min. A pilot bioavailability study was carried out in four normal healthy male volunteers. Urine samples were collected over a 48 h period and analysed for TRM, its major metabolite TRM-sulfate, and HCT using HPLC methods. The dissolution characteristics of TRM can be associated with the total drug excretion (absorption) of the product. On the other hand, the excretion (absorption) of HCT was independent of dissolution characteristics of the products. However, in TRM–HCT combination product, there appears to be a 50 per cent reduction in HCT excretion (absorption) when compared to the reported excretion (absorption) from a marketed single-entity product.     

Regulatory aspects of modifications to innovator bronchodilator metered dose inhalers and development of generic substitutes.

Regulatory requirements for modifications to an approved innovator metered dose inhaler (pressurized MDI; USP nomenclature: inhalation aerosol) and for development of a new generic product are discussed. Although many of the requirements apply generally to MDI's, they are discussed with specific reference to albuterol. Changes to the container and closure system may impact on the dosimetry of the redesigned product, as well as upon toxicologic and chemistry, manufacturing and controls (CMC) concerns. Changes to the formulation, including the use of alternate propellants, may raise issues requiring both clinical and in vivo performance evaluation. In view of the level of interest of a number of firms in approval requirements for generic Albuterol Inhalation Aerosol products, the article discusses in considerable detail the CMC and bioequivalence requirements for a generic product. Similarities in the CMC requirements for innovator and generic products are evident. Three comparative in vivo bioequivalence tests, particle size distribution, spray pattern and plume geometry, and unit spray content, established by the Division of Bioequivalence are discussed. Similarities and differences in the in vivo requirements for innovator and generic products are evident. Differences are the result of U.S. statute, which requires safety and efficacy testing for a product approved under a new drug application (NDA), but documentation of bioequivalence for a product approved under an abbreviated new drug application (ANDA). The advantages and disadvantages of three pharmacodynamic study designs which have potential usefulness for documentation of in vivo bioequivalence are discussed.     

Albendazole Generics—A Comparative In Vitro Study

Purpose. We sought to determine whether disintegration and dissolution behavior differs among various albendazole generic formulations obtained from third world countries and to compare them with the innovator's product. Methods. Dissolution behavior of various albendazole formulations was studied with USP Apparatus 2 in SGF_sp and in a modified SGF_sp which contained 0.1% of the nonionic surfactant Triton^® × 100. Disintegration was tested according to the European Pharmacopoeia. Results. Dissolution experiments in SGF_sp showed a wide range in rate and extent of albendazole dissolution. The innovator product released 81 percent within two hours, a profile matched by only one other formulation. For other formulations 32 to 64% was released within two hours. Use of a modified SGF_sp, containing 0.1% Triton^® × 100 to simulate the surface tension of gastric juice, resulted in less discrimination between products. The innovator product again showed the fastest and most complete dissolution, with ninety percent released within two hours. The generic formulations released between 67 and 82%, except for one formulation which achieved only 43% release. The results in SGF_sp plus Triton^® × 100 may be more meaningful than in SGF_sp, since the surface tension of the medium is closer to the physiological value. All formulations passed the disintegration test according to the European Pharmacopoeia, with disintegration times ranging from 2.5 to 11 minutes. Conclusions. Generic albendazole products vary widely in their dissolution behavior. Differences among products were greater in SGF_sp than in SGF_sp plus Triton^® × 100. These differences were not reflected in the disintegration behavior of the products.     

Correlation of aspirin excretion with parameters from different dissolution methods

The cumulative urinary excretion of four different aspirin products (two tablets, a capsule, and a timed-release tablet) was determined in a crossover study using five subjects. Comparison of in vivo results showed a significant difference in cumulative urinary excretion levels at only 1 hr. The excretion from the two regular tablets was significantly different from the timed-release tablet, but the capsule showed no significant difference from the other three products. Each product was tested in the USP, Levy beaker, and the regular and large magnetic basket dissolution apparatus. Analysis of variance of the in vitro results showed a significant difference between the aspirin products and the dissolution methods at selected times. In vitro comparison with in vivo results for the four products showed that a regression analysis can be used to determined which dissolution methods produce a significant correlation with urinary excretion.     

Assessment of the pharmaceutical quality of marketed enteric coated pantoprazole sodium sesquihydrate products

Pantoprazole sodium sesquihydrate (PSS) is a proton pump inhibitor, used in acid-related disorders, like peptic ulcer and gastroesophageal reflux. Increasing the number of pantoprazole containing products in the market, raises questions of its efficacy and generic substitution. The pharmaceutical quality of 6 generic PSS enteric coated tablets in 2 local markets was assessed relative to the innovator product (pantozol®). Uniformity of dosage unit, disintegration and in vitro drug release were determined using United States pharmacopeia for delayed release tablets. The similarity factor (f2) was assessed using the FDA recommended approach (f2 similarity factor). The content uniformity of the innovator product was 98.39% of the labeled claim with RSD value of 1.08%, while the content of generic products ranged from 96.98% to 98.80% with RSD values of 1.24–2.19%. All the products showed no disintegration, cracks or swelling in 0.1 N HCl, except product 1, which showed complete disintegration after 20 min. However, the disintegration of all the products in phosphate buffer met USP requirements. Dissolution of tablets in 0.1 N HCl showed no drug release after 2 h except product 1 in which one tablet showed a drug release more than 10% at acid stage level A1. In addition, three tablets of this product showed dissolution of 45%, 48% and 69% at acid stage level A2. The similarity factor f2 of the products was between 71 and 74 indicating the similarity in dissolution profiles of all the products in accordance to FDA requirements, except product 1 in which f2 value was 18.67.     

Dissolution Profile of Mefenamic Acid Solid Dosage Forms in Two Compendial and Biorelevant (FaSSIF) Media

Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) that is widely used for the treatment of mild-to-moderate pain. Mefenamic acid belongs to the Biopharmaceutical Classification System (BCS) class II drug which has lower water solubility but high permeability. There are two different compendial methods available for dissolution tests of mefenamic acid solid dosage forms, i.e. methods of United States Pharmacopeia 37 (USP) and Pharmacopoeia of the People’s Republic of China 2010 (PPRC). Indonesian Pharmacopeia V ed. (FI) adopted the USP method. On the other hand, many researches focused on the use of a ‘biorelevant’ medium to develop the dissolution test method. The aim of this research was to study the dissolution profile of mefenamic acid from its solid dosage forms (caplet and capsule) available in the Indonesian market with three different dissolution medium: USP, PPRC, and biorelevant fasted simulated small intestinal fluid (FaSSIF) media. The tested products consisted of the innovator’s product (available only in caplet dosage form, FN caplet) and generic products (available as caplet and capsule). The dissolution test of the drug products in all dissolution media was performed in 900 mL of medium using apparatus II (paddle) at a temperature of 37°C and rotation speed of 75 rpm, except for the capsule product and for USP medium, both of which tests were done using apparatus I (basket) with rotation speed of 100 rpm. The solubility test of mefenamic acid was carried out in all media at temperature of 37°C. The result obtained from the solubility test showed that the the highest solubility of mefenamic acid was obtained in USP medium (approximately 2 mg/mL), followed by PPRC medium (about 0.5 mg/mL), and FaSSIF medium (approximately 0.06 mg/ml). In the dissolution test, percentage of drug dissolved in in the USP and PPRC media after 45 min for all products reached more than 75%, except for the PN caplet in USP medium which reached only about 44%. Meanwhile, in the biorelevant medium, the percentage of drug dissolved for all products did not exceed 16%. In all dissolution media, the capsule dosage form achieved the highest dissolution rate.     

替代对照品法测定新疆孕马尿中3种主要结合雌激素含量

目的 建立HPLC替代对照品法测定新疆孕马尿中3种主要结合雌激素的含量。方法 采用HPLC在不同条件下测定替代对照品雌酮硫酸钠对于马烯雌酮硫酸钠及17α-双氢马烯雌酮硫酸钠对照品的校正因子,利用校正因子和替代对照品雌酮硫酸钠测定孕马尿中3种主要结合雌激素的含量。结果 以替代对照品法测得的结果与常规含量测定方法结果一致。结论 在高效液相色谱仪上使用替代对照品法测定孕马尿中的3种主要结合雌激素的含量,此方法准确可靠,可节约检测成本。     

In vitro and in vivo evaluation of seven 50 mg and 100 mg nitrofurantoin tablets

Four 50 mg and three 100 mg marketed nitrofurantoin tablets were studied in 14 healthy male subjects. Urine was collected 1, 2, 3, 4, 6, 8, 12, and 23 h after each dose, and nitrofurantoin was assayed by HPLC. The in vitro dissolution of the tablets was determined using USP Apparatus 1 and 2, with 0.1 N hydrochloric acid and pH 7.2 buffer as the dissolution fluids. One of the 50 mg tablets was more rapidly and completely absorbed than the other six products. The incidence of side-effects for this product was as low or lower than the other products. It was determined that the use of the USP Apparatus 1, at 100 rev min-1, with sampling of the pH 7.2 fluid at 30 min, provided for the best overall relationship between the urinary excretion and in vitro dissolution.     

Prediction of systemic exposure of ketoprofen tapes by in vitro release test and pharmacokinetic model analysis: comparison between brand-name and generic formulations

Topical dermatological formulations of non-steroidal anti-inflammatory drugs (NSAIDs) are reported to show their pharmacological effect partially through the systemic circulation, and to induce systemic side effects. However, pharmaceutical equivalence and pharmacokinetic bioequivalence between brand-name and generic products are not required. Therefore, we aimed to predict systemic drug exposure from brand-name and nine generic ketoprofen tapes. In vitro release profiles were examined using the paddle-over-disk method, then analyzed by the W. I. Higuchi equation incorporating an initial burst effect. Pharmacokinetic parameters were estimated from observed release profiles and the reported time-plasma concentration profile of the brand-name product. Plasma concentration profiles of generic products were predicted from the observed release profiles and the pharmacokinetic parameters of the brand-name product. In vitro release profiles differed markedly, and estimated release rates for initial burst effect and at 24 hours ranged from 4.20 to 88.75% and from 45.27 to 95.83%, respectively. The predicted plasma concentration profile of each product reflected its release profile, and estimated C(max) ranged from 61.70 to 290.30 ng/mL (0.46- to 2.15-fold vs. brand-name product). Generic products were classified into three types, i.e., systemic exposure comparable with, higher than and lower than that of brand-name product. C(max) was predicted to increase with enhanced skin permeability for all products, but the increase rates differed among products. These results suggest that safety and efficacy differ between brand-name and generic ketoprofen tapes. Healthcare professionals should carefully monitor systemic side effects, especially when switching from brand-name to generic products for which higher systemic exposure is predicted.     

The biliary excretion of acenocoumarol in the rat: stereochemical aspects

Within 24 h, 50% of a single dose of the acenocoumarol enantiomers was recovered in bile and 20% in urine of Wistar rats. The elimination products were mainly (>90%) the 6- and 7-hydroxyacenocoumarol as conjugates in the bile but free in the urine. Only R-acenocoumarol, free and conjugated, was excreted in bile. There were no gross differences between the enantiomers in metabolic pattern or in the amount of metabolites formed. A significant difference was observed for the biliary excretion of the 7-hydroxy metabolite; the ratio of free and conjugated 7-hydroxyacenocoumarol was three times higher for the S-than for the R-isomer. An unknown third metabolite was recovered in bile in higher amounts with the S- than with the R-acenocoumarol. Only traces of this metabolite were recovered from urine. The data show an extensive biliary excretion of acenocoumarol and demonstrate stereoselective mechanisms in the excretion processes.     

Dissolution test development for complex veterinary dosage forms: Oral boluses

Fundamental aspects of electrolyte chemistry were used to design an appropriate dissolution medium with the capacity to maintain sink conditions throughout the test. Dissolution of various bolus dosage forms was studied using USP Apparatus II at various stirring speeds. Complete dissolution of each drug in the designed medium was achieved, and there is evidence that such a dissolution test could be discriminating. This review details the development of potentially discriminating in vitro dissolution tests for veterinary boluses using USP Apparatus II and examines the potential role of such testing during product quality assessments, in the evaluation of postapproval manufacturing changes and for the establishment of the generic equivalence of veterinary products.