Pharmacopoeial Specifications Research Articles

Innovation of novel ‘Tab in Tab’ system for release modulation of milnacipran HCl: optimization, formulation and in vitro investigations

The study was aimed toward development of modified release oral drug delivery system for highly water soluble drug, Milnacipran HCl (MH). Novel Tablet in Tablet system (TITs) comprising immediate and extended release dose of MH in different parts was fabricated. The outer shell was composed of admixture of MH, lactose and novel herbal disintegrant obtained from seeds of Lepidium sativum. In the inner core, MH was matrixed with blend of hydrophilic (Benecel®) and hydrophobic (Compritol®) polymers. 32 full factorial design and an artificial neuron network (ANN) were employed for correlating effect of independent variables on dependent variables. The TITs were characterized for pharmacopoeial specifications, in vitro drug release, SEM, drug release kinetics and FTIR study. The release pattern of MH from batch A10 containing 25.17% w/w Benecel® and 8.21% w/w of Compritol® exhibited drug release pattern close proximal to the ideal theoretical profile (t50% = 5.92 h, t75% = 11.9 h, t90% = 18.11 h). The phenomenon of drug release was further explained by concept of percolation and the role of Benecel® and Compritol® in drug release retardation was studied. The normalized error obtained from ANN was less, compared with the multiple regression analysis, and exhibits the higher accuracy in prediction. The results of short-term stability study revealed stable chataracteristics of TITs. SEM study of TITs at different dissolution time points confirmed both diffusion and erosion mechanisms to be operative during drug release from the batch A10. Novel TITs can be a succesful once a day delivery system for highly water soluble drugs.

Individual oral therapy with immediate release and effervescent formulations delivered by the solid dosage pen.

New devices enabling freely selectable dosing of solid oral medications are urgently needed for personalized medicine. One approach is the use of the recently published Solid Dosage Pen, allowing flexible dosing of tablet-like sustained release slices from drug loaded extruded strands. Slices were suitable for oral single dosed application. The aim of the present study was the development of immediate release dosage forms for applications of the device, especially for young children. Using two model drugs, two different concepts were investigated and evaluated. Effervescent formulations were manufactured by an organic wet-extrusion process and immediate release formulations by a melt-extrusion process. Dissolution experiments were performed for both formulations to ensure the immediate release behavior. Extruded strands were individually dosed by the Solid Dosage Pen. Various doses of the two formulations were analyzed regarding uniformity of mass and content according to pharmacopoeial specifications. Proof of concept was demonstrated in both approaches as results comply with the regulatory requirements. Furthermore, storing stress tests were performed and drug formulations were characterized after storing. The results show that suitable packaging material has been selected and storage stability is probable.

Formulation Development and in vitro Evaluation of Drug Release Kinetics from Sustained Release Aceclofenac Matrix Tablets using Hydroxypropyl Methyl Cellulose

The objective of the present study was to develop a once-daily sustained release matrix tablet of Aceclofenac using hydroxypropyl methyl cellulose (Methocel K 100M CR) as release controlling factor and to evaluate drug release parameters as per various release kinetic models. The tablets were prepared by direct compression method. The powder blends were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity and drug content etc. The tablets were subjected to thickness, weight variation test, drug content, hardness, friability and in vitro release studies. The in vitro dissolution study was carried out for 24 hours using United States Pharmacopoeia (USP) 22 paddle-type dissolution apparatus in phosphate buffer (pH 7.4). The powder blends showed satisfactory flow properties, compressibility index and drug content etc. All the tablet formulations showed acceptable pharmacotechnical properties and complied with pharmacopoeial specifications. The results of dissolution studies indicated that the formulation F-3 (40% Methocel K100M CR of total weight of tablet) could extend the drug release up to 24 hours and the total release pattern was very close to the theoretical release profile. By comparing the dissolution profiles with the originator brand of Arrestin SR, the formulation F-3 exhibited drug release profile like originator brand. From this study, a decrease in release kinetics of the drug was observed by increasing the polymer concentration. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport, which was only dependent on the type and amount of polymer used. The drug release followed both diffusion and erosion mechanism in all cases. The drug release from the formulation (F-3) was satisfactory after 3 months storage in 400C and 75% RH. Besides, this study explored both of the optimum concentration and effect of polymer(s) on Aceclofenac release pattern from the tablet matrix for 24 hour period. The matrix tablet of Aceclofenac using HPMC with molecular weight of K100M controlled the drug release effectively for 24 hours; hence the formulation can be considered as a once daily sustained release tablet of Aceclofenac in order to improve patient compliance. DOI: http://dx.doi.org/10.3329/dujps.v11i1.12485 Dhaka Univ. J. Pharm. Sci. 11(1): 37-43, 2012 (June)

1545 The Use of Drug Manipulation to Obtain Doses Required in Paediatric Practice: A Systematic Review

Background and AimsTo determine whether there is an evidence base for drug manipulation to obtain the required dose, a common feature of paediatric clinical practice.MethodsSystematic review, including studies that considered...

Development and in vitro Evaluation of Sustained Release Matrix Tablets of Indapamide from Methocel® K15 MCR and K100 LVCR

Indapamide, a low-dose thiazide-type diuretic, is used for the treatment of essential hypertension. In this study, we developed an indapamide sustained release formulation using Methocel K15 MCR (a modified hydroxypropyl methylcellulose), Methocel K100 LVCR (a modified hydroxypropyl methylcellulose), magnesium stearate, talc and starch 1500 by direct compression. The powders for tableting were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity etc. The tablets were subjected to thickness, weight variation test, hardness, friability and in vitro release studies. The in vitro dissolution study was carried out in the gastric medium (pH 1.3) for first two hours and then in the intestinal medium (pH 6.8) for 22 hours using United States Pharmacopoeia (USP) 22 paddle-type dissolution apparatus. The granules showed satisfactory flow properties, compressibility index etc. All the tablets complied with pharmacopoeial specifications. The results of dissolution studies indicated that the formulation F-5 and F-7 (up to 75.36 % drug release in 12 hours) could extend the drug release up to 12 hours. The drug release patterns were simulated in different kinetic orders such as Zero Order release kinetics, First Order release kinetics, Higuchi release kinetics, Korsmeyer-Peppas release kinetics and Hixson-Crowell release kinetics to assess the release mechanism. From the study we observed that Higuchi release kinetics was the predominant release mechanism than Zero Order and First Order kinetics. The drug release mechanism from the matrix tablets was found to be non Fickian mechanism. DOI: http://dx.doi.org/10.3329/dujps.v10i2.11785 Dhaka Univ. J. Pharm. Sci. 10(2): 87-92, 2011 (December)

Formulation, standardization and pharmacological evaluation of a poly herbal traditional remedy -Ashwagandharishtam

Ayurvedic formulations were considered the best and safer alternatives for synthetic drugs. But the demand to such products is diminishing due to lack of standardization. Ashwagandharishtam, a fermented kind of ayurvedic formulation, is used to treat epilepsy, nervous disorders, skin diseases, immune disorders and rheumatism. In the present study, the standardization of Ashwagandharishtam using sophisticated techniques were attempted for assessing the quality and safety of herbal products involved in it. It was formulated according to a working formula and its physico-chemical, pharmacological and biological parameters were determined. The results of physicochemical studies showed that the values were under acceptable limits as per the Ayurvedic Pharmacopoeial specifications. FTIR studies of formulation revealed the presence of functional groups similar to Ashwagandha powder. The heavy metal content in the formulation is determined using Atomic Absorption Spectroscopy. HPTLC reports proved the presence of biomarker, withanolide-A in ashwagandharishtam which helped in its chemical standardization. The anti-epileptic activity of ashwagandharishtam was evaluated by Maximal electro shock (MES) method in rats. It exhibited a dose dependent significant (P < 0.001) reduction in various phases of epileptic seizures when compared with that of standard phenytoin. It was also assessed for its anti inflammatory activity in carrageen induced paw edema method which showed a good activity comparable to standard thus making it biologically standardized.

Capecitabine: An In-vitro Comparison between the Branded Xeloda? 500 Mg and its Intended Copy Capeda 500 Mg

Introduction: Dissolution is an example of in-vitro test which can be used to identify formulations that may present potential bioequivalence problems. It is defined as the amount of substance that goes into solution per unit time under standardised conditions of liquid/solid interface, solvent composition and temperature. It is considered one of the most important tools to predict the in-vivo bioavailability and in some cases replacing clinical studies to determine bioequivalence. Aim: To compare the differences in the dissolution behaviour between two anticancer formulations, Xeloda® 500 mg (reference product) and Capeda 500 mg (test product). Methods: Four replicates for each batch of the tested medicines were carried out using a PT-DT70 dissolution tester (Pharma Test) to detect any differences in their dissolution behaviour. Samples at nine time intervals were tested according to the US Pharmacopeia with the rate of dissolution determined by ultra-violet spectrophotometery. Results: All the tested medicines complied with the pharmacopoeial specifications, the EMA and the FDA guidance for industry when achieved 85% dissolution in 60 minutes. However, Capeda 500 mg (test product) showed slower, different and incomplete dissolution rate compared to Xeloda® 500 mg (reference product) at both 60 and 120 minutes. Other visual differences in the weight, size, clarity of solution, presence of un-dissolved residue and particles during the dissolution test were also detected. Conclusion: Results in this study clearly raise a question about the interchangeability between Xeloda® 500 mg and its Intended copy Capeda 500 mg. Awareness of these scientific concerns should be considered when a clinical choice between these two drugs is required. Differences between the innovator and copy medicines with regard to pharmacokinetics, clinical efficacy and safety may exist. Thereby, patients’ monitoring after performing drug substitution of these two medicines is strongly recommended.

Isolation and characterization of jackfruit mucilage and its comparative evaluation as a mucoadhesive and controlled release component in buccal tablets.

Background:The purpose of the present research work was to extract jackfruit mucilage, use it as a mucoadhesive agent, and to develop extended release buccoadhesive tablets with an intention to avoid hepatic first-pass metabolism, by enhancing residence time in the buccal cavity.Materials and Methods:The mucilage was isolated from the jackfruit pulp by the aqueous extraction method and characterized for various physiochemical parameters as well as for its adhesive properties. Three batches of tablets were prepared (wet granulation method) and evaluated containing three mucoadhesive components: Methocel K4M, Carbopol 974P, and isolated jackfruit mucilage using chlorpheniramine maleate (CPM) as a model drug and changing the proportion of the mucoadhesive component (1:2:3), resulting in nine different formulations.Results:The results of the study indicate that the isolated mucilage had good physicochemical and morphological characteristics, granules and tablets conformed to the Pharmacopoeial specifications, and in vitro release studies showed the sustained action of drug with increasing concentration of the isolated natural mucoadhesive agent in the formulations. Permeability studies indicated that changing the mucoadhesive component, permeability behavior was not statistically different (P > 0.05). FTIR and UV spectroscopy studies between mucilage and CPM suggested the absence of a chemical interaction between CPM and jackfruit mucilage.Conclusion:The developed mucoadhesive tablets for buccal administration containing natural mucilage (MF3) have a potential for the sustained action of drug release. Thus, mucoadhesive tablets for controlled release were successfully developed using natural jackfruit mucilage.

Formulation and evaluation of sublingual tablets of losartan potassium

ObjectiveSublingual tablets of Losartan Potassium were prepared to improve its bioavailability, to avoid pre-systemic metabolism in the gastrointestinal tract and hepatic first pass elimination. MethodsThe Sublingual tablets were prepared by direct compression procedure using different concentration of Starch 1500 and microcrystalline cellulose. Compatibility studies of drug and polymer were performed by FTIR spectroscopy and DSC. Preformulation property of API was evaluated. Postcompressional parameters such disintegration time, wetting time, water absorption ratio, in vitro drug release and in vivo bioavailability study of optimized formulation were determined. ResultsFTIR spectroscopy and DSC study revealed that there was no possible interaction between drug and polymers. The precompression parameters were in acceptable range of pharmacopoeial specification. The disintegration time of optimized formulation (F3) was upto 48 sec. The in vitro release of Losartan Potassium was upto 15 min. The percentage relative bioavailability of Losartan Potassium from optimized sublingual tablets was found to be 144.7 %. ConclusionsSublingual tablets of Losartan Potassium were successfully prepared with improved bioavailability.

The differences between the branded and generic medicines using solid dosage forms: In-vitro dissolution testing

IntroductionDissolution is the amount of substance that goes into solution per unit time under standardised conditions of liquid/solid interface, solvent composition and temperature. Dissolution is one of the most important tools to predict the in-vivo bioavailability and in some cases to determine bioequivalence and assure interchangeability. AimTo compare the differences in dissolution behaviour of solid dosage forms between innovators (reference products) and their generic counterparts (tested products). MethodsFour replicates for each batch of 37 tested medicines was carried out using A PT-DT70 dissolution tester from Pharma Test. A total of 13 branded medicines and 24 generic counterparts were obtained locally and internationally to detect any differences in their dissolution behaviour. They were tested according to the British Pharmacopeia, European Pharmacopeia and the US Pharmacopeia with the rate of dissolution determined by ultra-violet Spectrophotometery. ResultsMost tested medicines complied with the pharmacopoeial specifications and achieved 85% dissolution in 60min. However, some generic medicines showed significant differences in dissolution rate at 60 and 120min. Many generic medicines showed a slower dissolution rate than their branded counterparts such as the generic forms of omeprazole 20mg. Some showed an incomplete dissolution such as the generic form of nifedipine 10mg. Other generics showed faster dissolution rate than their branded counterpart such as the generic forms of meloxicam 15mg. Moreover, some generics from different batches of the same manufacturer showed significant differences in their dissolution rate such as the generic forms of meloxicam 7.5mg. Nevertheless, some generic medicines violated the EMA and the FDA guidelines for industry when they failed to achieve 85% dissolution at 60min, such as the generic form of diclofenac sodium 50mg. ConclusionMost medicines in this study complied with the pharmacopeial limits. However, some generics dissolved differently than their branded counterparts. This can clearly question the interchangeability between the branded and its generic counterpart or even among generics.

Orally disintegrating mini-tablets (ODMTs) – A novel solid oral dosage form for paediatric use

The new European regulations on paediatric medicines and recent WHO recommendations have induced an increased need for research into novel child-appropriate dosage forms. The aim of this study was the development of orally disintegrating mini-tablets (ODMTs) as a suitable dosage form for paediatric patients. The suitability of five commercially available ready-to-use tableting excipients, Ludiflash®, Parteck® ODT, Pearlitol® Flash, Pharmaburst® 500 and Prosolv® ODT, to be directly compressed into mini-tablets, with 2 mm in diameter, was examined. All of the excipients are based on co-processed mannitol. Drug-free ODMTs and ODMTs with a child-appropriate dose of hydrochlorothiazide were investigated. ODMTs could be produced with all investigated excipients. ODMTs with a sufficient crushing strength >7 N and a low friability <1% could be obtained, as well as ODMTs with a short simulated wetting test-time <5 s. ODMTs made of Ludiflash® showed the best results with crushing strengths from 7.8 N up to 11.8 N and excellent simulated wetting test-times from 3.1 s to 5.0 s. For each excipient, ODMTs with accordance to the pharmacopoeial specification content uniformity could be obtained. The promising results indicate that orally disintegrating mini-tablets may serve as a novel platform technology for paediatrics in future.

Bioadhesive Controlled Release Clotrimazole Vaginal Tablets

Purpose: To formulate bioadhesive clotrimazole vaginal tablets using natural polymers in order to provide long-term therapeutic action at the site of infection. Methods: The tablets were prepared by direct compression using bioadhesive polymer mixtures: hydroxypropyl methylcellulose/sodium carboxymethylcellulose (HPMC/NaCMC) and HPMC/Guar gum (GG) in different ratios. Differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopic evaluations were carried out to assess compatibility between the drug and the excipients. The tablets were subjected to various pre- and post-compression evaluations, including in vitro drug release, in vitro bioadhesive strength, swelling and stability studies. Results: The results show that all the formulations satisfied Indian Pharmacopoeial specifications for tablet parameters. DSC and FT-IR data indicate there was no interaction between the drug and the excipients. Drug dissolution rate at pH 6.0 followed the rank order: HPMC)/NaCMC > HPMC/GG. There was increase in swelling index with time at 37 0C. The combination of HPMC with NaCMC showed greater mucoadhesive strength and superior controlled drug release to the formulations prepared with GG polymer mixture. Furthermore, the release properties of the former in pH 6.0 buffer, as well as release mechanism (n values), were negligibly affected by ageing. Conclusion: This study indicates the possible use of suitable mixtures of natural and semi-synthetic cellulosic polymers for the preparation of clotrimazole mucoadhesive tablets for application as a vaginal controlled delivery system. Keywords: Clotrimazole, Swelling, Cellulosic polymers, Guar gum, Bioadhesion, Release properties

Novel delivery device for monolithical solid oral dosage forms for personalized medicine

There is an evident need for solid oral dosage forms allowing patients’ tailor-made dosing due to variations in metabolization or small therapeutic indexes of drug substances. The objective of this work is the development of a device equipped with a novel solid dosage form, containing carvedilol as model drug, for the delivery of monolithical drug carriers in individual doses. The device was developed and constructed enabling an exact feed rate and dose adjustment by a cutting mechanism. A twin-screw extruder was used for producing cylindrical solid dosage forms. Divided doses were characterized by mass variation, cutting behavior and drug dissolution in order to investigate their applicability for practical use. Different formulations could be extruded obtaining straight cylindrical rods, which are divisible in exact slices by using the novel device. Forces below 20 N were needed to divide doses which comply with pharmacopoeial specification “conformity of mass”. The developed formulations exhibit a sustained release of carvedilol within a range from 7 up to 16 h. A novel system consisting of a device and a cylindrical dosage form was developed. Patients’ individual doses can be applied as monolithical solid dosage forms for oral use.

Quality Assessment of the Commonly Prescribed Antimicrobial Drug, Ciprofloxacin Tablets, Marketed in Tigray, Ethiopia

An attempt was made to assess the quality and compare the physicochemical equivalence of six brands of ciprofloxacin tablets marketed in Tigray, Ethiopia. Six brands of ciprofloxacin tablets were used in the study. Identity, weight uniformity test, disintegration test, dissolution test and assay for the content of active ingredients were performed using the methods described in the British Pharmacopoeia. All the samples passed the identity, disintegration, and dissolution tests but Ciflox failed to release 80% of the drug content within 30 minutes as stipulated in the pharmacopoeia. This product therefore does not comply with the BP 2004 dissolution tolerance limits. All of the brands examined pass the assay for content of active ingredient. This work revealed that the six brands included in the study complied with the physicochemical quality parameters except Ciflox which failed to meet the pharmacopoeial specification for dissolution test. Nevertheless the six brands showed that there is significant difference in the drug release in vitro (p Keywords: Physicochemical properties; Quality; Bioequivalence; Dissolution rate; HPLC

Comparative Bioavailability Assessment of Newly Developed Flurbiprofen Matrix Tablets and Froben SR® Tablets in Healthy Pakistani Volunteers

Background: Flurbiprofen is a non-selective cyclo-oxygenase inhibitor, member of series of alkanoic acid derivatives, has anti-inflammatory, analgesic activity. Also used to treat gout, osteoarthritis, rheumatoid arthritis and is effective in inhibiting surgically induced miosis in human eyes while cataract extraction. Oral sustained release formulation as a novel matrix system of flurbiprofen tablets were prepared using Carboxy methylcellulose as release retardant. Objective: The aim of present study was comparative bioavailability assessment of newly developed flurbiprofen matrix tablets for sustained delivery, with commercially available Froben SR. Methods: Randomized, open-label, 2-periods, cross-over study conducted on 24 male healthy volunteers in Pakistan. Small batch of flurbiprofen matrix tablets were manufactured and evaluated according to Pharmacopoeial specifications. Each volunteer received a 200-mg tablet of the test and reference formulations, separated by a 7-day washout period. Blood samples were obtained before dosing 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 12, and 24 hours after drug administration. Safety monitoring was performed which includes adverse events. Plasma concentrations of the 2 formulations were determined, and pharmacokinetic parameters were compared using noncompartmental analysis. In-vivo disposition kinetics was evaluated using single dose, cross over, complete two period of treatment design in twenty four healthy male human volunteers; the drug was assayed in plasma using HPLC-UV detection, and results were compared. Various pharmacokinetic parameters (Cmax, Tmax, area under the curve [AUC0-24], mean residence time) and relative bioavailability were compared. Results: No significant differences were found for Cmax, Tmax,AUC and other parameters. The rate and extent of drug release from matrix tablets was not significantly different from commercially available Froben SR tablets. An in vivo result indicates prolonged blood levels with delayed peak and comparable bioavailability. Conclusions: The matrix tablets could also provide, sustained, gastrointestinal environmentalindependent release that may result in an improved therapeutic efficacy.

Quality assessment of different marketed brands of Dasamoolaristam, an Ayurvedic formulation

Arista is a classical Ayurvedic preparation that is typically used as a digestive and cardiotonic. The present Investigation evaluated five different brands of Dasamoolaristam available in the market as per WHO and Indian Pharmacopoeial specifications. Various physicochemical parameters such as alcohol-soluble extractive, water-soluble extractive, total ash, acid-insoluble ash, total solid, and alcohol content were determined. The present investigation reveals that all the preparations contain acceptable levels of alcohol (less than 12% v/v). However, the preparations were found to contain unacceptable limits of microbial load although all showed the absence of Escherichia coli, Salmonella species, and Staphylococcus aureus.

Quality specifications for peptide drugs: a regulatory‐pharmaceutical approach

Peptide drugs, as all types of pharmaceuticals, require adequate specifications (i.e. quality attributes, procedures and acceptance criteria) as part of their quality assurance to ensure the safety and efficacy of drug substances (i.e. active pharmaceutical ingredients) and drug products (i.e. finished pharmaceutical dosage forms). Compendial monographs are updated regularly to keep up with the most recent advances in peptide synthesis (e.g. reduced by-products) and analytical technology. Nevertheless, currently applied pharmacopoeial peptide specifications are barely harmonized yet (e.g. large differences between the European Pharmacopoeia and the United States Pharmacopeia), increasing the manufacturers' burden of performing analytical procedures in different ways, using different acceptance criteria. Additionally, the peptide monographs are not always consistent within a single pharmacopoeia. In this review, we highlight the main differences and similarities in compendial peptide specifications (including identification, purity and assay). Based on comparison, and together with additional information from peptide drug substance manufacturers and public evaluation reports on registration files of non-pharmacopoeial peptide drugs, a consistent monograph structure is proposed.

Formulation and In Vitro Evaluation of Release Retardant Diclofenac Sodium Tablets Using Hydrophilic and Waxy Matrices

Development of release retardant matrix tablets of diclofenac sodium for 24 h by wet granulation technique using different combinations and ratios of hydroxypropylmethylcellulose (HPMC), sodium carboxymethylcellulose (sodium CMC), sodium alginate and cetostearyl alcohol was carried out. The tablets were evaluated for thickness, diameter, D/H ratio, hardness, weight variation, drug content and in vitro drug release studies. The tablet formulations showed acceptable pharmacotechnical properties and complied with pharmacopoeial specifications for the tested parameters. All the formulations showed extended drug release up to 12 h and the formulation prepared with drug : HPMC in 1:4 ratio using water as granulating agent (F10) extended the drug release up to 24 h with initial burst effect. Upon modification, using ethyl cellulose as granulating agent (F11) extended drug release up to 24 h that followed zero order release kinetics (r2 = 0.9872). Model independent parameters such as t25%, t50%, t90%, DE720 and mean dissolution time (MDT) were also determined

Identification and quantification of N-linked oligosaccharides released from glycoproteins: An inter-laboratory study

As characterization of glycosylation is required for the licensing of recombinant glycoprotein therapeutics, technique comparability must be assessed. Eleven UK laboratories (seven industrial, two regulatory or government, two academic) participated in an inter-laboratory study to analyze N-glycans present in four mixtures prepared by PNGase F cleavage of commercial glycoproteins: human alpha1-acid glycoprotein (H alpha1), bovine alpha1-acid glycoprotein (B alpha1), bovine pancreatic ribonuclease B (RNaseB), and human serum immunoglobulin G (hIgG). Participants applied their routine glycan mapping methodology using predominantly chromatography and mass spectrometry to identify and quantify components. Data interpretation focused on the relative amounts of different glycan structures present, the degree of sialylation, antennary and the galactosylation profiles, fucosylation and bisecting GlcNAc content, and the number of glycan components identified. All laboratories found high levels of sialylation for H alpha1 and B alpha1 (Z-numbers 271 +/- 24 and 224 +/- 18, respectively), but varying ratios of di-, tri-, and tetra-antennary chains. The Z-score for hIgG glycans had high variability as values obtained from mass spectrometric and chromatographic methods clustered separately. The proportion of the major penta-mannosyl chain from RNaseB was between 29 and 62%. Proportions of fucosylated and bisected GlcNAc chains from hIgG were between 58 and 96% and 9 and 23%, respectively. Mass spectrometric approaches consistently identified more glycan species, especially when both N-glycolylneuraminic acid (Neu5Gc) and N-acetylneuraminic acid (Neu5Ac) were present. These data highlight the need for well-characterized reference standards to support method validation and regulatory guidance on selection of approaches. Pharmacopoeial specifications must acknowledge method variability.

Differentiating Low-Molecular-Weight Heparins Based on Chemical, Biological, and Pharmacologic Properties: Implications for the Development of Generic Versions of Low-Molecular-Weight Heparins

Low-molecular-weight heparins (LMWHs) are polypharmacologic drugs used to treat thrombotic and cardiovascular disorders. These drugs are manufactured using different chemical and enzymatic methods, resulting in products with distinct chemical and pharmacologic profiles. Generic LMWHs have been introduced in Asia and South America, and several generic suppliers are seeking regulatory approval in the United States and the European Union. For simple small-molecule drugs, generic drugs have the same chemical structure, potency, and bioavailability as the innovator drug. Applying this definition to complex biological products such as the LMWHs has proved difficult. One major issue is defining appropriate criteria to demonstrate bioequivalence; pharmacopoeial specifications alone appear to be inadequate. Whereas available generic versions of LMWHs exhibit similar molecular and pharmacopoeial profiles, marked differences in their biological and pharmacologic behavior have been noted. Preliminary studies have demonstrated differences in terms of anti-Xa activity and tissue factor pathway inhibitor release after subcutaneous administration, as well as antiplatelet and profibrinolytic effects. The current data emphasize the need to consider multiple functional parameters when defining bioequivalence of biologic drugs with complex structures and activities and also underscore the importance of further pharmacologic studies involving animal models and human clinical trials. The U.S. Food and Drug Administration and the European Medicine Evaluation Agency are currently developing guidelines for the acceptance of biosimilar agents including LMWHs. Until such guidelines are complete, generic interchange may not be feasible.