The purpose of this study is to compare the clinical efficacy of erythropoietin gel containing a solution of 4000 units with triamcinolone acetonide 0.1% gel in the treatment of symptomatic oral lichen planus (OLP)

At the first visit before the initiation of the study;

• Information including age, gender, disease process, medical history, drug history, family history, and clinical symptoms and signs will be documented.
• Patients will be examined clinically by magnifying mirror using a spotlight for the oral lesions, the distribution of the lesions and the affected areas will be recorded, and a punch biopsy will be taken to confirm the diagnosis.

Twenty-four patients seeking treatment for symptomatic OLP will be assessed for eligibility for this study. Patients will be recruited from the outpatient clinic, department of Oral Medicine and Periodontology, Faculty of Dentistry, and the Department of Skin and Venereal Disease, Faculty of Medicine, Ain Shams University.

The study will be conducted according to the ethical principles provided by the Declaration of Helsinki and according to the principles of good clinical practice. Faculty of Dentistry-Ain Shams University Research Ethical Committee (FD-ASU-RECD) will review the protocol, the procedure will be fully explained to the patients. Each patient will receive detailed verbal and written information about the study protocol. Understanding and agreement to enroll in the study will be confirmed and written consent forms will be obtained.

II- Study design, interventions, blinding, randomization, and grouping:

The study is designed as a Randomized- parallel 2 arm - assessor blinded single center- controlled comparative clinical trial with immunohistochemical analysis.

• Interventions The oral Gel carrier of the intervention will be designed, prepared, and in vitro characterized at the Pharmaceutical Science Department, Faculty of Pharmacy- Ain University.
• Patients grouping Patients who met the eligibility criteria will be randomly assigned to 2 different treatment regimens using computer-generated random tables and allocation concealment;

Group I Will include twelve patients with oral lichen planus lesions receiving ( erythropoietin mucoadhesive thermosensitive hydrogel), twice daily (Experimental Arm)

Group II:

It will include twelve patients with oral lichen planus lesions receiving (Topical corticosteroid 0.1%) four times per day for 8 weeks (Positive control arm) In the fourth- and eighth both patients in group II will receive topical antifungal (Miconazole 2%) to avoid secondary candidiasis while patients in group I will receive topical antifungal only if needed

Inclusion Criteria:

1. Clinically proven painful symptomatic forms of OLP confirmed by the presence of red or erythematous changes, or shallow ulcerations with fine lacy lines at the periphery of the lesion accentuated by stretching and not eliminated by rubbing (Wickham's striae)
2. Histopathological proven symptomatic OLP

Exclusion Criteria:

1. History of the drug-induced lichenoid lesion.

2. Presence of systemic conditions as; serious active or recurrent infections, malignancy, diabetes mellitus, hypertension, or significant heart, liver, or renal diseases. Assessed using a medical questionnaire guided by the Cornell Medical Index

3. Smoking

4. Known hypersensitivity or severe adverse effects to the treatment drugs or to any ingredient of their preparation as mentioned in history

5. Pregnancy or breastfeeding.

6. History of previous treatments potentially effective on OLP such as antimalarial agents, retinoids, corticosteroids, or immunosuppressive drugs from less than 2 weeks for topical medications, and 4 weeks for systemic medications before starting the study

7. Loss of pliability or flexibility in the tissues involved by the lesions of OLP.

8. Histological signs of epithelial dysplasia or lichenoid lesions within the biopsied sites.

9. Patients with extensive skin lesions and indicated for systemic corticosteroids.

10. Vulnerable groups (Handicapped, orphans, or prisoners)

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