Research, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ARTICLE INFO ABSTRACT
Article history
Received 23/12/2013
Available online
31/12/2013
Keywords
Disulfiram,
Milling, Micronization,
Aqueous wet granulation,
Bioequivalence under Fasting.
Tetraethylthiuram disulphide is chemical name of Disulfiram. There are few manufacturers
available worldwide involved in the manufacture of Disulfiram Tablets due to its high bio
variability from patient to patient. Disulfiram is available as immediate release tablets and
effervescent / dispersible tablets. There is a report of high bio variability between the
marketed, effervescent / dispersible tablets vis a vis immediate release tablets. Moreover, with
respect to manufacturing of disulfiram tablets, the manufacturing process followed worldwide
involves dry granulation by roller compaction / slugging method. The tablets thus prepared
have very poor mechanical strength; rough edges are observed around the tablet
circumference; when the marketed tablets are subjected to friability testing, tablets are failing
in friability test owing to capping; some set of tablets show % friability in the range of 0.6-0.85% with severe edge wearing. To overcome this problem, a set of manufacturers perform
the blend compression by extending the dwell time to prevent capping of tablets. Another set
of manufacturers make the tablets with co-processed excipients. In some of the marketed
product, Tween 80 or Myrj 52 is used as wetting agent, which may intervene with the P-gp
efflux mechanism precipitating high bio variability of Disulfiram. In the present research,
Disulfiram Tablets were manufactured by aqueous wet granulation process. Manufactured
tablets showed good morphology and mechanical strength, without tableting issues. In this
research apart from robust manufacturing process, influence of milling and micronization of
API on the in vivo bio variability of the drug was studied and reported.
Please cite this article in press as Venkateswaran Chidambaram Seshadri,et al. Formulation and evaluation of tetraethylthiuram
disulphide tablets by aqueous wet granulation process .Indo American Journal Of Pharm Research.2013:3(12).
Tetraethylthiuram disulphide is chemical name of Disulfiram. Disulfiram is an alcohol deterrent used for the treatment of
chronic alcoholism. Apart from the treatment of alcoholism it is being studied for the treatment of cocaine dependence. Disulfiram is
also useful in the treatment of Giardia infection and Scabies. Disulfiram has good activity against metronidazole resistant
Trichomonas vaginalis. Disulfiram creates dithiocarbamate complexes with metals which is a proteasome inhibitor. A clinical trial of
Disulfiram with copper gluconate against liver cancer is being conducted in Utah. A clinical trial in Israel evaluates the Disulfiram as
adjuvant against liver cancer. Currently, Disulfiram is the subject of research for use as a treatment in HIV cure through activating the
reservoir of HIV-infected resting CD4 cells. Recently a report suggests the role of Disulfiram as a P-gp efflux pump modulator;
Disulfiram inhibits ATP hydrolysis and binds to drug substrate binding sites of multiple ABC transporters which are associated with
drug resistance and is thus potentially an attractive agent to combat multidrug resistance. Disulfiram also possess the potentialas an antifungal agent. In a recent research, Disulfiram was screened for its antifungal potential on a spectrum of 61 fungal isolates. MIC50
and MIC90 of Disulfiram is better than Fluconazole, Amphotericin B, Itraconazole, Voriconazole and Cancidas in the case of Candida
parapsilosis, C. krusei, C. albicans, C. tropicalis, C. glabrata, Aspergillus fumigatus, A. flavus and A.niger. Disulfiram was also found
to be active against non-Candida yeast like Cryptococcus neoformans and Histoplasma capsulatum. Further, azoles are fungistatic in
nature whereas Disulfiram showed fungicidal activity against the tested fungal cultures of Candida parapsilosis, C. krusei, C. albicans,
C. tropicalis, C. glabrata, Aspergillus fumigatus, Cryptococcus neoformans and Histoplasma capsulatum. Antifungal potential of
Disulfiramwas tested against 13 Aspergillus isolates. Like amphotericin B, Disulfiram showed fungicidal potential activity with MIC50
and MIC90 of 2 and 8 µg /ml respectively. Disulfiram also has beneficial effect on symptoms caused by a lack of Vitamin E. Early
research has showed that certain dental diseases caused by lack of Vitamin E could be cured by Disulfiram. Disulfiram is a cream-
white colored, odourless, slightly bitter tasting, crystalline powder, practically insoluble in water, 0.02 g / 100 mL. Disulfiram readily
diffuses into cells and raise the intracellular thiol levels and hence can act on intracellular redox reactions. Disulfiram also has the ability to inhibit the xanthine oxidase and succinoxidase enzyme systems. Disulfiram also possess antithyroid action due to the NCS
group in its structure, which is common to many antithyroid compounds, probably producing stable complex through reaction with
free iodine. Disulfiram is rapidly absorbed from the gastrointestinal tract but the absorption is incomplete and about 20% is excreted
in the faeces. Disulfiram has high lipid solubility, hence widely distributed and accumulated in various fat depots. Disulfiram is a
prodrug which is rapidly metabolized to diethylthiocarbamate (DDC), and formed DDC is partly excreted as CS2 (carbon disulphide)
in the expired air through lungs and is partly metabolized in the liver to Me-DDC. Further, Me-DDC is metabolized to the active
metabolite MeDTC (diethylthiocarbaminic acid methyl ester). The concentration of Me-DTC reaches maximum after about 4 hours,
but the maximum enzyme-inhibiting effect (ALDH) is first reached (steady state) after 3 daily doses. The t1/2 for Me-DTC is about 10
hours, but the enzyme inhibiting effect of ALDH lasts significantly longer. Metabolism is not affected by a mild to moderate reduction
in liver function. On the contrary, in presence of liver cirrhosis an increased concentration of the metabolites is seen in the blood. The
metabolites are mainly excreted in the urine. Part is recovered in the expired air in the form of CS2 (Carbon Disulphide). About 20%
of administered dose may remain in the body for one week or longer. [1-20] The aim of the research is to make Disulfiram Tablets which will exhibit a better mechanical strength and morphology as compared to the marketed product. Disulfiram being a highly
variable drug, this research will also focus on the influence of milling and micronization of API on bioavailability of the drug product
and accordingly particle size specification of API will be finalized. Disulfiram API exhibits poor flow and compressibility. Direct
blending and compression process was not selected. Dry granulation and slugging method was not selected since the marketed product
samples made with the slugging process showed rough edges around the tablet circumference; when the marketed tablets are subjected
to friability testing, tablets are failing in friability test owing to capping; some set of tablets show % friability in the range of 0.6-
0.85% with severe edge wearing. Hence it was decided to formulate the Disulfiram tablets by aqueous wet granulation method.
Hydroxypropyl cellulose (Klucel LF) was selected as binder. Silicified Microcrystalline Cellulose (Prosolv SMCC HD 90) was
selected as diluent. Sodium Starch Glycolate Type A (Primojel) was selected as disintegrant. Colloidal Silicon Dioxide (Aerosil 200)
was selected as glidant and antistatic agent. Stearic Acid (Stellipress 1200 Poudre) and Non Bovine Grade Magnesium Stearate
(Tablube) were selected as lubricants.
MATERIALS AND METHODS
Excipients & Reagents
Disulfiram was obtained from Farchemia, Italy; Silicified Microcrystalline Cellulose (Prosolv SMCC HD 90) was obtained
from JRS Pharma Germany; Sodium Starch Glycolate Type A (Primojel) was obtained from DFE Pharma Germany; Hydroxypropyl
Cellulose (Klucel LF) was obtained from Ashland Inc USA; Non Bovine Grade Magnesium Stearate (Tablube) was obtained from
Nitika Chemicals India; Colloidal Silicon Dioxide (Aerosil 200) was obtained from Evonik Germany; Stearic Acid (Stellipress 1200
Poudre) was obtained from Stearinerie Dubois FIIs France; Sodium Lauryl Sulphate (Stepanol WA100) was obtained from Stephane
USA; Ethanol and Methanol were obtained from Avantor Performance Materials, India; Potassium Dihydrogen Phosphate, Potassium
Hydroxide were obtained from Merck Specialities Ltd India.
Equipments& Instruments High Shear Mixer Granulator 10 Litres manufactured by Kevin Process Technologies Private Limited; Fluid Bed Dryer
Processor & Granulator GPCG 1.1 manufactured by Pam Glatt Technology Limited; 16 Station Single Rotary Tablet Compression
Machine manufactured by Cadmach Machinery; Hardness Tester Type: TBH 125 manufactured by Erweka; Disintegration Test
Apparatus Model ED 2L manufactured by Electrolab; Thickness Tester Vernier Caliper Absolute Digimatic manufactured by
Mitutoyo; Friabilator EF-1W manufactured by Electrolab; Electromagnetic Sieve Shaker EM8-08 Plus manufactured by Electrolab;
Tap Density Testing Apparatus ETD-1020 manufactured by Electrolab; Bottle Sealing Machine (Induction Cap Sealer) Sigma Flex
manufactured by Electronic Devices; Double Cone Blender with interchangeable bowls of 5L, 15L and 25L manufactured by Sams
Technomech; Loss On Drying Mositure Analyzer Model MB 45 manufactured by Ohaus; Multi Mill equipped with 1.5 mm screen
manufactured by Sams Technomech; Comminuting Mill equipped with 0.25 mm screen manufactured by Cadmach Machinery; MC
JetMill®50 manufactured by Dietrich Engineering Consultants, Switzerland; 40°C / 75% RH Stability Chamber manufactured by
Thermolab Scientific Equiments; HPLC manufactured by Waters; Vibrosifter manufactured by Gansons Engineering; 12.8 mm Round
Shaped Standard Concave Punch Tooling manufactured by ACG PAM Pharma Technology; Weighing Machine PS6000/C/1
manufactured by LCGC RADWAG; pH Meter H12215 manufactured by Hanna Instruments; Lab Stirrer RQ-126D manufactured by
Remi; Dissolution Apparatus TDT-08L manufactured by Electrolab;
Disintegration and Dissolution Parameters
Disintegration test was performed in USP disintegration test apparatus in Purified Water @ 37 ± 0.5°C. Specification: NMT
15 minutes. Dissolution was performed in 900 mL Purified Water with 2% Sodium Lauryl Sulphate. The parameters include, USP-II
(Paddle), 100 RPM. Time Points: 15, 30, 45, 60, 75, 90, 105 and 120 minutes. λmax at 254 nm. Specification: NLT 75 % (Q) of the
labeled amount in 120 minutes.
Method For Assay, Blend Uniformity, Content Uniformity / Uniformity of Dosage Units and Dissolution
Disulfiram is official in USP and the same method was utilized for the determination of Assay, Related Substances, Blend
Uniformity, Content Uniformity / Uniformity of Dosage Units and Dissolution
Method For Bulk Density, Tapped Density, Repose Angle and Friability Measurements USP guidelines followed in the measurement of Bulk Density, Tapped Density, Compressibility Index, Hausner Ratio,
Repose Angle and % Friability measurements.
Experimental/ Methodology
Marketed Product Characterization
Antabuse®(Disulfiram) Tablets 250 mg and 500 mg manufactured by Duramed Pharmaceuticals Inc. Subsidiary of Barr
Pharmaceuticals Inc. USA was characterized with respect to Inactive ingredients details, Weight, Thickness, Diameter, Disintegration
Time and Dissolution Profile and Packaging configuration.
API Characterization
Disulfiram was characterized with respect to Description, Bulk Density, Tapped Density, Compressibility Index, Hausner
Ratio, Repose Angle and Particle Size Distribution.
Drug-Excipient Compatibility Study
The possibility of drug-excipient interaction was investigated by HPLC analysis. Drug excipient compatibility study was
performed with excipients mentioned above (See ‘Excipients & Reagents’). Study was conducted by preparing homogenous mixture
of excipient with drug filled in glass vials were exposed to 40 ± 2°C / 75 ± 5%RH and 60°C for 4 weeks and 2 weeks respectively.
Samples were analysed for Assay, Total Impurity and Water By Kf.
Formulation
The Hydroxypropyl Cellulose (Klucel LF) required for the batch was divided into two parts, 70% of the total batch quantity
of Hydroxypropyl Cellulose (Klucel LF) was dissolved in terms of 12% w/w solids in Purified Water as a binder solution. The
remaining 30% of the total batch quantity of Hydroxypropyl Cellulose (Klucel LF) was sifted along with Disulfiram and Sodium Starch Glycolate (Primojel) through # 20 ASTM sieve. The sifted materials were charged in High Shear Mixer Granulator and dry
mixed at high impeller and chopper speed for 15 minutes. The dry mixed materials were granulated with binder solution of
Hydroxypropyl Cellulose (Klucel LF) at high impeller and chopper speed. The binder solution container was rinsed with purified
water which is 12% of the total quantity of binder solution prepared and rinsings were added to the contents of High Shear Mixer
Granulator. The wet granules were dried in Fluid Bed Dryer Processor & Granulator at 50°C till LOD is not less than or equal to 1%.
The dried granules were milled through Multi Mill equipped with 1.5 mm screen at fast speed knife forward configuration. The milled
granules were blended in Double Cone Blender at 15 RPM for 5 minutes. The extra granular materials except lubricants was sifted
through #20 ASTM sieve and blended along with granules of intragranular part in a Double Cone Blender at 15 RPM for 15 minutes.
The lubricants were sifted through #40 ASTM sieve and blended with the blended materials in a Double Cone Blender at 15 RPM for
5 minutes. The blend thus prepared was compressed into tablets using 12.8 mm Round Shaped Standard Concave Punch Tooling. The
details of Formulation Prototypes are shown in Table 1. The drying parameters are as follows,
Inlet Air Temperature – 50° +5°C; Exhaust Temperature – 40°+5°C; Filter Shaking Interval – 20 ± 5 seconds; Shaking Duration – 5 ± 1 second; Shaking Mode – Auto
Total Extragranular Ingredients 160.00 160.00 170.000 157.500 145.00 145.00
Total Tablet Weight 700.00 700.00 700.000 700.000 700.00 700.00
EVALUATION
The blend of all prototypes was characterized with respect to LOD, Repose Angle, Bulk / Tapped Density, Hausner Ratio and
PSD. Prepared Tablets were characterized with respect to Weight, Thickness, Hardness, Friability, Disintegration Time and
Dissolution Profile.
Stability Studies
The finalized formulation of all strengths was subjected to accelerated stability study at 40±2°C / 75±5% RH. 100 Tablets
were packed in 150 cc HDPE bottle with 38 mm Child Resistant Cap with cotton as dunnage and induction sealed. Description,
Disintegration Time, Dissolution, Assay and Related Substances were studied during stability. In case of dissolution, method followed
was USP-II (Paddle), 100 RPM, 900 mL, Purified Water with 2% Sodium Lauryl Sulphate @ 37 ± 0.5°C. Time Points: 15, 30, 45, 60,
75, 90, 105 and 120 minutes. Specification: NLT 75 % (Q) of the labeled amount in 120 minutes.
In vivo Studies
An open-label, balanced, randomized, three-treatment, three-period, three-sequence, single-dose, crossover, bioequivalence
study of Disulfiram Tablets, 500 mg (made with micronized API – Test 1), Disulfiram Tablets, 500 mg (made with milled API - Test
2), with that of Reference product, Antabuse® (Disulfiram) Tablets 500 mg was conducted in 15 healthy adult human subjects under fasting condition. The study protocol was prepared and approval from Independent Ethical Committee – The Ethical Jury, Chennai
was obtained. The studies were conducted in compliance with the ethical principles of the Declaration of Helsinki, the International
Conference on Harmonization’s Good Clinical Practices guidelines and the guidelines of Indian Council of Medical Research for
Biomedical Research on Human Subjects and Good Clinical Practices for Clinical Research in India. Study subjects were screened
and enrolled for the study. Enrolled subjects were housed in the clinical facility for 11 hours prior to drug administration until 24
hours post dose. In case of study under fasting condition, after overnight fasting of at least 10 hours, a single oral dose of either tests or
reference product was administered to the subjects and to swallow it with about 240 mL of water in sitting posture. Then the subject
will be fasted for at-least 4 hours post dosing. The pre-dose 0 hour blood sample was collected before dosing and post dose samples
were collected at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 6.0, 6.5, 7.0, 8.0, 10.0, 12.0, 16.0, 24.0, 36.0, 48.0 and 72.0 hours. Subjects were
provided standard diet and continuously monitored for well-being and safety throughout the study. The concentration of S-methyl
N,N-diethyldithiocarbamate (Me-DDC), which is an active metabolite of Disulfiram in plasma samples were analysed using validated analytical method. Pharmacokinetic and statistical analyses were performed on obtained drug concentration data. Healthy, willing
human volunteers between 18 and above were selected on the basis of medical history, physical examination (including but may not
be limited to an evaluation of the cardiovascular, gastrointestinal, respiratory and central nervous systems) vital sign assessments, 12-
lead electrocardiogram (ECG), X-ray, and clinical laboratory assessments, urine screen for drugs of abuse and alcohol breath test.
Informed consent was obtained from the subjects after explaining the nature and purpose of the study. Pharmacokinetic analysis was
performed using WinNonlin® software version: 5.3 of Pharsight Corporation, USA for the following pharmacokinetic parameters
Cmax, AUC0-t, AUC0-∞, Tmax, Kel, , t½ , Kel_Lower, Kel_Upper and AUC_%Extrap_obs. Analysis of variance (ANOVA)
consistent with two one-sided test for bioequivalence, ratio analysis and 90% confidence intervals for ratio of least square mean of Ln-
transformed data of Cmax, AUC0-t and AUC0-∞ for tests and reference products were calculated by using SAS® statistical software
version 9.1.3 from SAS Institute Inc, USA. For Disulfiram, in terms of S-methyl N,N-diethyldithiocarbamate (Me-DDC), which is an
active metabolite of Disulfiram, the 90% confidence interval of the relative mean Cmax, AUC0-t and AUC0-∞ of the tests and
reference product should be between 80.00% and 125.00% for log-transformed data.
Distribution of API was done and the details are provided in Table 3.Compressibility Index, Hausner Ratio and Flow property of API is poor and needs to be improved through formulation.
Drug-Excipient Compatibility Study
Drug Excipient compatibility data shown in Table 4. suggests that both the temperature and moisture doesn’t affect the
stability of mixture indicating compatibility of drug with excipients studied.
Table 2. Marketed Product Characterization. Mean ± SD
Note:TI – Total Impurity; % Moisture determined by Water by Kf.
FORMULATION
For the prototype Batches A to E, milled API was used and the granulation, drying, milling, prelubrication and lubrication
blending time were kept constant. The blend prepared was compressed with uniform hardness into tablets. Blend of batch A showed
poor flow; disintegration time of tablets was more than 8 minutes; picking, sticking and striation were observed during blend
compression. To overcome the tableting issues of picking, sticking and striation, in batch B the concentration of Stearic Acid
(Stellipress 1200 Poudre) and Magnesium Stearate (Tablube) were doubled from 6 mg to 12 mg and 1 mg to 2 mg respectively. Blend
of batch B showed poor flow; disintegration time of tablets was more than 8 minutes; picking, sticking and striation were not observed
during blend compression. Increase in Disintegration time may be due to excess binder concentration, hence in batch C the
concentration of Hydroxypropyl Cellulose (Klucel LF) was reduced from 30 mg to 20 mg. Blend of batch C showed poor flow;
disintegration time of tablets has improved from 8 minutes to 6 minutes. To overcome the poor blend flow and slow disintegration
time of tablets, in batch D the concentration of Sodium Starch Glycolate Type A (Primojel) was increased from 10 mg to 22.5 mg in the intragranular part and 8 mg to 16 mg in the extragranular part; the concentration of Colloidal Silicon Dioxide (Aerosil 200) was
API + Excipients Tests Initial Duration / Storage Conditions
increased from 8 mg to 16 mg in the extragranular part. Blend of batch D showed good flow and the disintegration time of tablets has
improved from 6 minutes to 4 minutes. To further improve the disintegration time of tablets, in batch E the concentration of Sodium
Starch Glycolate Type A (Primojel) in the intragranular part was increased from 22.5 mg to 35 mg. Tablets of Batch E showed
disintegration time of about 2 minutes. Blend and Tablet characteristics of Batch E was found to be optimal. The same composition
was used for the preparation of Disulfiram Tablets (Batch F) manufactured with Disulfiram (Micronized) API. With the composition
of batch E, Disulfiram Tablets were manufactured and the process parameters were optimized. The characterization study for blend
and tablets were done and are summarized in Table 5. In Batch E, Blending time optimization study was taken up as part of process
optimization study. Blending time optimization involves two stages of study, Prelubrication blending time and Lubrication or final
blending time. In Prelubrication blending time, the sifted extra granular ingredients except lubricant were blended along with blended
milled granules in double cone blender at 15 RPM, the blend uniformity samples were sampled in duplicate at different location in the blender at the end of 10 minutes, 15 minutes and 20 minutes. In the lubrication or final blending time the sifted lubricants were
blended along with the blended materials in the double cone blender at 15 RPM, the blend uniformity samples were sampled in
duplicate at different location in the blender at the end of 4, 5 and 6 minutes. See Table 6 for details. Based on the blend uniformity
data, blending time of 15 minutes was finalized for the Prelubrication stage and blending time of 5 minutes was finalized for the
lubrication stage. This optimized blending time will be followed in the manufacturing process of lower strength, 250 mg. After
blending time optimization study, compression process was optimized with respect to turret speed (RPM) and hardness variation
study. Turret speed and its influence on the prepared tablets were characterized by weight variation and content uniformity, based on
the results the turret speed range was finalized. In hardness variation study, the tablets are compressed at different hardness range and
the influence of the same on thickness variation, % friability, disintegration time and dissolution were studied and accordingly a
suitable hardness range was finalized.
Table 5. Blend and Tablet Characterization. Mean ± SD
Particulars
A B C D E F
Dry Mix Time(min) 15 15 15 15 15 15
Dry Mix LOD (%) 0.96 0.78 0.68 0.77 0.92 0.62
Dry Mix Bulk Density ( g / ml) 0.17 0.14 0.19 0.17 0.14 0.14
Medium: 900 ml, Purified water @ 37 ± 0.5ºC, USP-II (Paddle), 100 RPM, Specification: NLT 75% (Q) in 120 minutes
Dissolution Profile Comparison of Test Product Vs Marketed Product
Dissolution profile of the prepared tablets of Disulfiram was compared against the marketed product, Antabuse®(Disulfiram)
Tablets, 500 mg. The dissolution profiles of both Batch E (Milled API) and Batch F (Micronized API) were on the higher side except
the 15th minute time point as compared to the marketed product Antabuse®(Disulfiram) Tablets, 500 mg. The extent of drug release of the prepared tablets was better as compared to the marketed product. At the end of 120 minutes, the test products showed drug release
of about 100% whereas the marketed product showed about 83% drug release. Both the test products complied to the dissolution
specification of not less than 75% (Q) in 120 minutes. See Table 11 and Figure 1 for further details.
Table 11. Dissolution Profile Comparison of Test Products Vs Marketed Product. Mean ± SD
White to off-white colored, uncoated, round shaped biconvex tablets; on stability no morphological change observed.
In vivo Bioequivalence Study
In vivo studies were carried out for test formulations, Batch F (Mirconized API – Test 1) and Batch E (Milled API – Test 2)
against the reference product Antabuse® (Disulfiram) Tablets. The plasma levels of Disulfiram, in terms of S-methyl N,N-
diethyldithiocarbamate (Me-DDC), which is an active metabolite of Disulfiram was determined. The mean concentration-time profiles
for the marketed and test products of Disulfiram under fasted condition were shown in Table 13 and Figure 2 respectively. The Test
product – 1 made with micronized API was found to be bioinequivalent to the marketed product in terms of Cmax, AUC0-t and AUC0-∞. The T/R ratio of the test product-1 with respect to Cmax, AUC0-t and AUC0-∞was found to be 178.20%, 136.39% and 137.26%
respectively. The 90% Confidence Interval of the T/R ratio with respect to Cmax, AUC0-t and AUC0-∞ was found to be in range of
155.89 – 203.71%, 119.18 – 156.08% and 120.08 – 156.91% respectively. With respect to Tmax the test product-1 is 2.5 hours whereas
the Tmax of the reference product is 4.5 hours. Test product 1 made with micronized API reaches peak plasma concentration at a rapid
rate than the reference product. The particle size of micronized API d90 is 12.38 microns. Based on the bioequivalence results of test
product 1 against the reference product, Micronization of API causes rapid dissolution and the drug reaches the peak plasma
concentration within 2.5 hours. Hence for the formulation of Disulfiram tablets, micronization of API is not required. The Test
product – 2 made with milled API was found to be bioequivalent with the Reference product in terms of AUC0-t and AUC0-∞ and
bioinequivalent with respect to Cmax. The T/R ratio of the test product-2 with respect to Cmax, AUC0-t and AUC0-∞was found to be
123.27%, 108.10% and 108.45% respectively. The 90% Confidence Interval of the T/R ratio with respect to Cmax, AUC0-t and AUC0-∞
was found to be in range of 107.84 – 140.92%, 94.46 – 123.71% and 94.87 – 123.97% respectively. With respect to Tmax the test
product-2 is 4.5 hours exactly matching with the Tmax of the reference product which is also 4.5 hours. Test product 2 made with milled API reaches peak plasma concentration at a similar rate as that of the reference product. The particle size of milled API d90 is
83.33 microns. Based on the bioequivalence results of test product 2 against the reference product, Milling of API causes drug
dissolution and absorption at a similar as that of the reference product and the drug reaches the peak plasma concentration at 4.5 hours.
Hence for the formulation of Disulfiram tablets, milling of API is required to be bioequivalent with that of the reference product.
Regarding the bioinequivalence of Test product 2 with respect to Cmax against the reference product, the issue is precipitated because
of biovariability in plasma levels of Disulfiram, in terms of S-methyl N,N-diethyldithiocarbamate (Me-DDC), which is an active
metabolite of Disulfiram. On careful analysis of the pharmacokinetic data sheet of this study with respect to minimum, maximum and
% RSD values of Cmax of reference product vis a vis test product-2 the biovariability factor (Volunteer to volunteer) plays a major role.
The minimum, maximum and % RSD values of Cmax of reference product & test product–2 are 23.3109 ng/ml, 145.8652 ng/ml and
63.1063% & 23.0799 ng/ml, 112.7645 ng/ml and 38.1768% respectively. Based on the above facts, to achieve bioequivalence with
that of the reference product, Disulfiram tablets needs to be formulated with milled API and in the bioequivalence study, considering the biovariability of Disulfiram the number volunteers needs to be increased to reduce the intra subject variability for both the test and
Figure 2 Mean Concentration Time Profile – Fasted Study
CONCLUSION
Disulfiram tablets were successfully formulated by a simple aqueous wet granulation process. Disulfiram is an insoluble and
highly biovariable drug. Disulfiram drug product is available in 2 strengths in the market namely 250 mg and 500 mg. Tablet
morphology, mechanical strength, disintegration time and dissolution were fixed as prerequisite design attributes. Formulation was initiated for highest strength, 500 mg using milled API. Hydroxypropyl cellulose (Klucel LF) was selected as binder. Silicified
Microcrystalline Cellulose (Prosolv SMCC HD 90) was selected as diluent. Sodium Starch Glycolate Type A (Primojel) was selected
as disintegrant. Colloidal Silicon Dioxide (Aerosil 200) was selected as glidant and antistatic agent. Stearic Acid (Stellipress 1200
Poudre) and Non Bovine Grade Magnesium Stearate (Tablube) were selected as lubricants. The finalized prototype batch E showed
favorable blend and tablet characteristics. The disintegration and dissolution profile of the tablets were also found to be satisfactory.
The blend was characterized by determining bulk density, tapped density, hausner ratio, compressibility index, loss on drying, repose
angle and particle size distribution. Blending time optimization studies were taken in Batch E. Prelubrication blending time was
finalized at 15 minutes; Lubrication blending time was finalized at 5 minutes based on blend uniformity data at different time
intervals. Further, turret speed optimization & hardness variation optimization was done and was characterized by determining weight
variation and content uniformity & hardness variation, thickness variation, % friability, disintegration time and dissolution
respectively. Based on the data, the turret speed was finalized in the range of 10-30 RPM and hardness was finalized in the range of
10-20 kP. After finalization of composition, the same formula was utilized for the formulation of Disulfiram tablets with micronized
API. Disulfiram tablets made with both milled and micronized API showed comparable disintegration and the dissolution profile to
the marketed product, ANTABUSE® manufactured by Duramed Pharmaceuticals Inc. Subsidiary of Barr Pharmaceuticals Inc. USA.
Disulfiram tablets made with both milled and micronized API were subjected to accelerated stability study in HDPE bottle pack and
the physico-chemical properties were found to be stable. The prepared Disulfiram tablets made with both milled and micronized API
was subjected to in vivo bioequivalence study under fast condition against the reference / marketed product, ANTABUSE®
manufactured by Duramed Pharmaceuticals Inc. Subsidiary of Barr Pharmaceuticals Inc. USA. Disulfiram Tablets made with milled API showed promising bioequivalence with that of the marketed product.
Future Research – In vivo bioequivalence study under fasting needs to be taken up with higher number of human volunteers to
reduce the biovariability and to establish the bioequivalence of Disulfiram Tablets made with milled API against the marketed product
ANTABUSE®.
Authors’ Statements
Competing Interests - The authors declare no conflict of interest.
REFERENCES 1. http://www.fda.gov/ohrms/dockets/ac/04/slides/40345S2_02_DiLiberti.ppt.(Accessed on 11/12/2013) 2. Anderson MP., Lack of bioequivalence between disulfiram formulations. Exemplified by a tablet / effervescent tablet study,
Acta.Psychiatr.Scand.Suppl. 1992, 369, 31-35. 3. http://www.google.com/advertorial case study-GEA Courtoy’s Performa P at Sanico, Begium – Survey of production runs on the Performa P. 4. Naveen Pathak et al., Formulation and Optimization of Immediate Release Tablet of an Antialcoholic Drug by Dry Granulation Method,
Pharmacie Globale. 2001, 2:3; 1-4. 5. Efficiency of High Functionality Excipients in Preparation of High Dose Drugs with the help of Roller Compaction Technology, Int.J.Ph.Sci.
2011, 3:1;, 1096-1102.
6. http://www.dailymed.com/labelinformation of disulfiram tablets. (Accessed on 11/12/2013) 7. http://en.wikipedia.org/wiki/disulfiram. (Accessed on 11/12/2013) 8. Nash T et al., Efficasies of zinc-finger-active drugs against Giardia lamblia, Antimicrobial agents and chemo. 1998, 42:6; 1488-92 9. Bouma MJ et al., Activity of Disulfiram (bis(diethylthiocarbamoyl) disulphide) and ditiocarb (diethyldithiocarbamate) against metronidazole
sensitive and resistant Trichomonasvaginalis and Tritrichomonasfoetus, J.Antimicro.Chemo. 1998, 42:6; 817-820 10. Doyon et al., Disulfiram reactivates latent HIV-1 expression through depletion of the phosphatase and tensin homolog, AIDS. 2013, 27:2; F7-
F11 11. Landegren J et al., Treatment of scabies with Disulfiram and benzyl benzoate emulsion: A controlled study, Actadermato-venereologica. 1979,
59:3; 274-276
12. Cvek B et al., Targeting of Nuclear Factor-ƙB and proteasome by dithiocarbamate complexes with metals, Curr.Pharm.Des. 2007, 13:30; 3155-3167
13. Cvek B et al., The value of proteasome inhibition in cancer, Drug.Dis.Today. 2008, 13:15-16; 716-22
14. Wickstrom Malin et al., Pharmacological profiling of Disulfiram using human tumour cell lines and human tumour cells from patients, Biochem.Pharmacol. 2007, 73:1; 25-33
15. Sauna et al., The molecular basis of the action of Disulfiram as a modulator of the multidrug resistance-linked ATP binding cassette transporters MDR1 (ABCB1) and MRP1 (ABCC1), Mol.Pharmacol. 2004, 65; 675-684
16. Seema Khan et al., Short Report - Antifungal Potential of Disulfiram, Jpn.J.Med.Mycol. 2007, 48; 109-113 17. Sauna ZE et al., Disulfiram, an old drug with new potential therapeutic uses for human cancers and fungal infections, Mol. Biosystems. 2005,
1:127-134 18. HelgeKragh., From Disulfiram ToAntabuse: The Invention of a Drug, Bull.Hist.Chem. 2008, 33:2; 82-88 19. http://www.google.com/product information Antabuse® (Disulfiram) 200 mg Effervescent Tablets (Accessed on 11/12/2013)
20. Sritharan Seetharaman., Narayanan Nallaperumal., Once Daily Venlafaxine Hydrochloride Extended Release Tablets: Comparison Between Matrix Tablet and Pellets, Int. J. Pharm. Sci. Rev. Res, 2012; 13: 149-153.
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