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Bioequivalence & Bioavailability International Journal Research Article 8 min read

Physicochemical and In-Vitro Bioequivalence Analysis of Some Oral Solid-Dosage Metronidazole Formulations

Bunu SJ*, Kpun FH, Obasi FC, Kashimawo AJ, Vaikosen EN and Ebeshi BU
* Corresponding author
ISSN: 2578-4803  10.23880/beba-16000221  Received: November 01, 2023  Published: December 14, 2023
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Keywords
Thin-Layer Chromatography Metronidazole Nitroimidazole Antibiotics Anti-Infective
Abstract

Background: Metrodidazole is a 5-nitroimidazole antimicrobial agent, widely used in the treatment of infections caused by Trichomonas vaginalis, such as trichomoniasis, pseudomembranous colitis, and symptomatic amoebiasis resulting from anaerobic bacteria. Aim: The study aimed to qualitatively determine the quality and in-vitrobioequivalence of selected brands of metronidazole tablet dosage forms used in the management of infectious diseases. Method: The British Pharmacopeia (BP) Standard methods were followed to conduct weight uniformity, disintegration time, hardness, and friability tests. For the Thin Layer Chromatographic (TLC) Fingerprinting, 0.1g of the brands were weighed and dissolved ins 50 ml methanol (50%). The stock solution was prepared using 50% methanol and 50% dichloromethane and was transferred into the Chamber and allowed to stand for about 45 minutes; the plates were viewed under UV-VIS Spectrophotometer at 365 nm. Result: All the brands complied with the acceptable friability limit, and disintegrated within the appropriate time of not more than 15 minutes as specified in BP, for uncoated tablets. The tablets were found to have a dissolution profile of at least 70% of the active ingredient taken at 45 minutes from the dissolution medium as stated in BP. The analysis showed the consistency of concentration of the selected tablet brands with the label claims. Conclusion: The TLC procedure used in the analysis was accurate and precise, no interference was observed from the excipients. Thus, this method can be used in the routine quality control of metronidazole solid dosage form.

Discussion

There are several reasons why drug items of low quality are produced, such as using substandard raw materials and lack of equipment. Quality control is therefore necessary. Pharmacopeia testing compares these attributes to predefined standards for verification. In Owerri Metropolis, South-East Nigeria, several retail pharmacy establishments supplied several brands of metronidazole pills Table 1, which were then put through testing for weight variation, friability, hardness, and disintegration. We also performed thin-layer chromatographic fingerprinting on the different brands of metronidazole formulations. All of the sample brands satisfied the BP [35] weight variation requirement Table 2, which states that for tablets weighing 250 mg or more, the weight of no more than two tablets shall fluctuate by 5%. Both the amount of the pharmaceutical ingredient (API) in a product and good manufacturing practice (GMP) can be determined by weight fluctuation [26].

Even though it’s not official, hardness testing is a crucial in-process method to determine whether the tablets being made are solid enough to resist cracking, chipping, or crumbling, but not so hard as to cause them to dissolve more slowly [36]. 4 to 8 kgF is the acceptable range [37]. Every brand sample matched the allowable limit Table 3. The resistance of a tablet to abrasion is measured by its tablet friability [35]. 1% is the permitted upper level [35]. Friability values for each brand sample were within the acceptable range Figure 2. The use of a binder with low adhesive strength or not employing a binder at all, along with tableting with little compressing force, are indicated by the high friability values [38].

Figure 2: Friability Test Results of the metronidazole brands and percentage (%) deviation from the initial and final samples. Percentage deviation from BP Standard is 0.1% - 0.5%.
Click to enlarge
Figure 2: Friability Test Results of the metronidazole brands and percentage (%) deviation from the initial and final samples. Percentage deviation from BP Standard is 0.1% - 0.5%.

A disintegration test for the various brands of metronidazole tablets was conducted using a disintegration test apparatus. All the brands of metronidazole disintegrated within the acceptable limit of not more than 15 minutes as specified in El-Nahhas TM [35], for uncoated tablets Table 4. According to Riley, et al. [39], one of the most significant quality control procedures is in-vitro dissolution testing, which can provide crucial details regarding batch consistency and biological availability. However, a practical and affordable way to forecast absorption and bioavailability variations between capsule and tablet versions of the same medication is by in-vitro dissolution testing [40]. The achievement of a dissolving profile is advised as a tool for drug formulation development and optimization, as well as the construction of in-vitro/in-vivo correlations. All the brands examined using the BP method were found to have a dissolution profile of at least 70% of active ingredients taken at 45 minutes from the dissolution medium as stated in BP [35].

It was observed that all the brands of metronidazole tablets sampled had acceptable levels of bioequivalence and this can be used interchangeably following the physicochemical parameters analysis. This shows that there are no significant differences in the pharmaceutical, chemical, and bioequivalence amongst the samples evaluated. However, there was variation in the pharmaceutical parameters of the samples. Samples A, B, C, D, E, and F, none failed the hardness, weight variation disintegration, and dissolution test. Therefore, the findings from this study indicate that invitro dissolution profiles of different metronidazole tablet formulations could be used to predict the in vivo bioequivalence; suggesting a relationship between invitro dissolution and some pharmacokinetic parameters such as tmax, Cmax, and AUC, which are necessary in defining the rate and the extent of drug availability in the systemic circulation.

Thin layer chromatographic fingerprint of different bands of metronidazole was carried out using Silica gel as the stationary phase and Dichloromethane 50% and methanol 50% as the mobile phase (Figure 3).

Figure 3: TLC chromatogram under daylight (A), and Iodine tank (B). The above figure shows the thin-layer chromatogram of various brands of metronidazole tablets. The Rf was obtained for the different samples ranging from 0.82 (A), 0.84 (B), 0.82 (C), 0.82 (D), 0.82 (E), and 0.84 for sample F respectively.
Click to enlarge
Figure 3: TLC chromatogram under daylight (A), and Iodine tank (B). The above figure shows the thin-layer chromatogram of various brands of metronidazole tablets. The Rf was obtained for the different samples ranging from 0.82 (A), 0.84 (B), 0.82 (C), 0.82 (D), 0.82 (E), and 0.84 for sample F respectively.

The lack of a significant difference between the Rf values at p-value < 0.05 indicated the relativeness (safety, efficacy, etc.) of the different brands included in the analysis. The recommended method is simple, delicate, precise, accurate, and economical. Since the analysis does not involve the use of organic solvents, the medicine does not need to be pre- treated, and there is no need for a laborious extraction process before the results can be determined, making it an environmentally benign technology. Furthermore, the suggested methodologies’ application to the examination of the pharmaceutical formulation demonstrates that excipients do not obstruct the determination. Hence, can be used in routine quality control.

Figure 1: Structure of metronidazole: C6H9N3O3 (2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethan-1-ol).
Click to enlarge
Figure 1: Structure of metronidazole: C6H9N3O3 (2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethan-1-ol).
Sample codeABCDEF
Batch4355ZA191239001810HRC20006ATE-160TE-2741
NAFDACApr-53Apr-66Apr-26Apr-66Apr-01Apr-21
Strength400 mg400 mg200 mg400 mg400 mg500 mg

Table 1: Six Different brands of Metronidazole used in the study.

No. of MeasurementsSample Code
A (%)B (%)C (%)D (%)E (%)F (%)
10.13.75.71.60.142.5
20.32.24.70.240.1
31.10.20.9112.22.4
40.72.13.41.53.51
50.30.27.74.51.81.8
60.43.41.73.10.70.5
73.71.12.20.70.10.9
81.61.67.80.11.40.2
90.12.50.60.20.80.4
100.71.70.20.11.21.4
Mean ± SD0.9±1.11.9±1.23.5±2.91.3±1.52.6±3.61.1±0.9

Table 2: Weight Variation (%Deviation).

No of measurementsSample Code
ABCDEF
14.5118.95.514.56.1
2510.9105.113.35.8
34.91410.9512.55.9
44.511114.3166.2
5410.3104.912.55.8
64.710.111.25.4155
74.8118.54135.4
8511.411514.86.5
95.315116154.3
10515114.513.55
Mean ± SD4.8±0.412.0±2.010.4±1.05.0±0.614.0±1.25.6±0.7

Table 3: Hardness Test (kgf).

Number of
Measurements		Sample Code
A(min)B (min)C (min)D (min)E (min)F (min)
10.570.472.396.52.1210.45
21.021.012.587.092.38.08
31.071.043.027.342.5511.52
41.11.073.117.54312.06
51.21.133.198.33.213.1
61.281.223.268.473.315.07
Mean ± SD1.04 ± 0.230.99 ± 0.242.93 ± 0.327.54 ± 0.682.75 ± 0.4511.71 ± 2.17

Table 4: Disintegration Time.

Conclusion

Like any other test method currently in use, the methodology employed in this study is appropriate and helpful for routine quality control analysis and quantification of the metronidazole dosage form in pharmaceutical formulations. The TLC procedure used in the analysis was accurate, precise, and cost-effective, and no interference was observed from the excipients.Therefore, in situations when advanced pharmaceutical tools and methods are unavailable, this approach can be used for the regular quality control of metronidazole in tablets and other comparable pharmaceutical formulations.

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@article{bunu2023,
  title   = {Physicochemical and In-Vitro Bioequivalence Analysis of Some
Oral Solid-Dosage Metronidazole Formulations},
  author  = {Bunu SJ, Kpun FH, Obasi FC, Kashimawo AJ, Vaikosen EN and Ebeshi BU},
  journal = {Bioequivalence & Bioavailability International Journal},
  year    = {2023},
  volume  = {7},
  number  = {2},
  doi     = {10.23880/beba-16000221}
}
Bunu SJ, Kpun FH, Obasi FC, Kashimawo AJ, Vaikosen EN and Ebeshi BU (2023). Physicochemical and In-Vitro Bioequivalence Analysis of Some
Oral Solid-Dosage Metronidazole Formulations. Bioequivalence & Bioavailability International Journal, 7(2). https://doi.org/10.23880/beba-16000221
TY  - JOUR
TI  - Physicochemical and In-Vitro Bioequivalence Analysis of Some
Oral Solid-Dosage Metronidazole Formulations
AU  - Bunu SJ, Kpun FH, Obasi FC, Kashimawo AJ, Vaikosen EN and Ebeshi BU
JO  - Bioequivalence & Bioavailability International Journal
PY  - 2023
VL  - 7
IS  - 2
DO  - 10.23880/beba-16000221
ER  -