Avalilação PREreview de Formulation and Evaluation of PVA-Stabilized Nanoemulsion Loaded with Methylsulfonylmethane for the Treatment of Experimentally Induced Arthritis

STUDY QUESTION: 

The study aims to develop and evaluate a polyvinyl alcohol (PVA)-stabilized nanoemulsion for the transdermal delivery of Methylsulfonylmethane (MSM) to enhance its solubility, stability, and bioavailability for the effective treatment of experimentally induced arthritis.

MAJOR CONCERNS

·        Critical Formulation Discrepancy: There is a fundamental inconsistency in the composition of the nanoemulsion. The text in Section 2.2 repeatedly states that clove oil was used as the oil phase. However, Table 1 and the chemicals list in Section 2.1 specify Medium-chain triglycerides (MCT oil). This discrepancy must be resolved, as the choice of oil core is a critical formulation parameter affecting stability, drug solubility, and biological activity.

·         Contradictory Zeta Potential Data: The zeta potential data is irreconcilable. Table 3 reports low positive values (+1.5 to +4.5 mV), which would suggest a highly unstable formulation. In stark contrast, Section 3.3.1 and Figure 1 report a strongly negative value of -32 mV, which indicates excellent electrostatic stability. This critical contradiction undermines the credibility of the stability claims and must be investigated and corrected.

·         Insufficient Methodological Detail for EE%: The protocol for determining Encapsulation Efficiency (EE%) and Drug Loading Capacity (DLC) in Section 2.5.2 is incomplete. The manuscript does not describe the crucial step of how the unentrapped/free drug was separated from the nanoemulsion (e.g., centrifugation, dialysis, filtration). This omission makes the experiment impossible to reproduce.

·         In Vivo Dosing Information Missing: The methodology for the in vivo anti-arthritic study (Section 2.5.11) lacks essential details. The dose of MSM applied (e.g., mg/kg), the volume of nanoemulsion administered, and the frequency of application are not specified. This information is vital for interpreting the efficacy results and for any future replication of the study.

MINOR CONCERNS

·         Role of PVA: The title and abstract highlight "PVA-Stabilized" as the key innovation. However, the formulation (Table 1) uses Tween 80 and Span 80 as primary surfactants. The specific role and advantage of PVA as a "stabilizer" in this nanoemulsion system, as opposed to the surfactants, should be more clearly defined and justified in the introduction or discussion.

·         Redundant Methodology Sections: Sections 2.5.4 (Zeta Potential Measurements Nanoemulsions) and 2.5.5 (Analysis of Nanoemulsion Droplet Size) are redundant with 2.5.1, as they describe the same technique using the same instrument. These should be consolidated to improve readability.

·         In Vitro Release Exceeding 100%: The in vitro drug release profile for formulation F5 (Figure 4) shows a cumulative release of 103.2%, which is unusual. A brief explanation for this result (e.g., analytical error, specific property of the method) should be provided in the results or discussion section.

·         Typographical and Formatting Errors: The manuscript contains several minor errors, including:

                                i.            "Pharmmacy" (Author affiliations).

                              ii.            "Muhamamad Adnan" (Author list).

                            iii.            "SM with M" (Section 2.5 header).

                            iv.            "Zetapotential" (Table 3 header).

                              v.            Incorrect table citations (e.g., viscosity data is in Table 5 but text refers to Table 6).

COMMENTS ON THE AVAILABILITY OF DATA

The manuscript states that "The data presented in this study are available on request from the corresponding author." While this is acceptable, it would align better with modern open science practices to encourage deposition of data in a publicly available repository (e.g., Zenodo, Figshare) to ensure permanent, unambiguous access and further enhance the study's reproducibility and impact.

COMMENTS ON GENERALIZATION OF CONCLUSION

The conclusions are well-supported by the extensive data presented (in vitro, ex vivo, in vivo). However, a key limitation should be explicitly acknowledged: the study was conducted on rabbits. The translational potential for human use, while promising, requires direct validation. The conclusion should be tempered to state that the formulation is a promising candidate for clinical trials, rather than implying direct applicability to humans. The excellent biocompatibility results are a strong positive indicator for this translational potential.

COMMENTS ON LOGICAL ARRANGEMENT IN RESULTS SECTIONS

The results section is comprehensive but would benefit from improved logical grouping and flow. Currently, it jumps between characterization data (size, PDI, zeta), stability, and then back to more characterization (viscosity, pH). A more intuitive structure would be:

·         Primary Physicochemical Characterization: Present all core data (Droplet Size, PDI, Zeta Potential, EE%, Viscosity, pH) for all formulations (F1-F5) together, explaining the selection of the optimized formula (F5).

·         Chemical and Morphological Analysis: Present the ATR-FTIR and SEM results to confirm compatibility and structure.

·         Stability Studies: Present the stability data of the optimized formulation (F5) under various conditions.

·         Performance Studies: Then logically progress through the performance data: In vitro release -> Ex vivo permeation -> In vivo efficacy -> Skin irritation.

·         This rearrangement would tell a clearer story: from "what we made and its basic properties" to "how stable it is" to "how well it performs."

OVERALL COMMENT

This is a well-conceived and generally well-executed study. The research question is relevant, the experimental design is robust, and the combination of physicochemical, stability, and biological testing is a significant strength. The results demonstrate a highly promising nanoemulsion system for the transdermal delivery of MSM. Addressing the major concerns, particularly the formulation discrepancy and contradictory zeta potential data, is essential to solidify the manuscript's foundation. Once these issues are resolved and the minor points are addressed, this manuscript will have the potential to be a strong contribution to the literature.

ACKNOWLEDGEMENT

We thank the authors for sharing their work as a preprint. This commitment to open science facilitates early dissemination of valuable research, encourages collaborative feedback, and accelerates scientific progress. The authors are to be commended for their comprehensive investigation into a novel drug delivery system for a common and debilitating condition.

Competing interests

The authors declare that they have no competing interests.