Table 1.

Summary of protocols analyzed in post-COVID-19 patients affected by anosmia.

Study Title	Intervention/Drug	Phase	Location	Age	Intervention Model and Allocation	Masking
Investigating the Potential Role of Aerosolized Retinoic Acid, a Potent Vitamin A Metabolite, for Treating COVID-19 Anosmia and Retinoic Acid Insufficiency. A Novel Approach for Regaining Sense of Smell. (NCT05002530) [14].	Aerosolized 13-cis retinoic acid plus Vitamin D/Aerosolized All trans-retinoic acid plus Vitamin D	Phase 4	Quan Liu Foshan, Guangdong, China Tamer Haydara Kafr Ash Shaykh, Kafr Elshiekh, Egypt Ministry of Health, Saudi Arabia.	18 years to 70 years	Parallel Assignment Randomized	None (Open Label)
Cerebrolysin for Treatment of COVID-related Anosmia and Ageusia NCT04830943 [15].	Cerebrolysin	Phase 4	Assiut University Hospitals, Faculty of Medicine Assiut, Egypt	20 years to 50 years	Parallel Assignment Randomized	None (Open Label)
COVID-19 Anosmia Study NCT04495816 [13].	Omega-3 Fatty Acid Supplement	Phase 2	Mount Sinai Hospital New York, New York, United States	18 years and older	Parallel Assignment Randomized	Double (Participant, Investigator)
Corticosteroid Nasal Spray in COVID-19 Anosmia NCT04484493 [16].	Mometasone furoate nasal spray	Phase 3	Benha University Hospital, Faculty of Medicine Banhā, Qalubia, Egypt	18 years and older	Parallel Assignment Randomized	None (Open Label)
Stellate Ganglion Block for COVID-19-Induced Olfactory Dysfunction NCT05445921 [17].	Stellate Ganglion Block	Phase 1 Phase 2	Washington University School of Medicine/Barnes Jewish Hospital Saint Louis, Missouri, United States	18 years to 70 years	Single Group Assignment	None (Open Label)
Role of Ivermectin Nanosuspension as Nasal Spray in Treatment of Persistent Post COVID19 Anosmia NCT04951362 [18].	Intranasal spray ivermectin	Phase 2 Phase 3	Zaky Aref Qina, Egypt	18 years to 70 years	Parallel Assignment Randomized	None (Open Label)
Efficacy of Gabapentin for Post-COVID-19 Olfactory Dysfunction NCT05184192 [19,20].	Gabapentin gelatine capsules 300 mg	Phase 2	Washington University Saint Louis, Missouri, United States	18 years to 65 years	Parallel Assignment Randomized	Triple (Participant, Investigator, Outcomes Assessor)
Smell in COVID-19 and Efficacy of Nasal Theophylline NCT04789499 [19].	Theophylline Powder	Phase 2	Washington University School of Medicine in Saint Louis Saint Louis, Missouri, United States	18 years to 70 years	Parallel Assignment Randomized	Double (Participant, Investigator)
Intranasal Insulin for COVID-19-related Smell Loss NCT05461365 [21].	Insulin	Phase 3	Universidad Panamerican Mexico City, Mexico	18 years to 59 years	Single Assignment	None (Open Label)
Anosmia and/or Ageusia and Early Corticosteroid Use NCT04528329 [22].	Early Dexamethasone/Late dexamethasone	Phase 4	Asalam Maadi, Cairo, Egypt	18 years and older	Parallel Assignment Randomized	None (Open Label)
Study of Hesperidin Therapy on COVID-19 Symptoms (HESPERIDIN) NCT04715932 [23].	Hesperidin	Phase 2	Montreal Heart Institute Montréal, Quebec, Canada	18 years and older	Parallel Assignment Randomized	Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Effect of Nasal Steroid in the Treatment of Anosmia Due to COVID-19 Disease NCT04569825 [24].	Ophtamesone	Phase 1	Raid Muhmid Al-Ani Ramadi, Anbar, Iraq	18 years and older	Parallel Assignment Randomized	Double (Participant, Investigator)
Effectiveness and Safety of Platelet Rich Plasma (PRP) on Persistent Olfactory Dysfunction Related to COVID-19 NCT05226546 [25].	Platelet-rich plasma (PRP)	Phase 2 Phase 3	CHU Saint Pierre Bruxelles, Belgium	18 years and older	Parallel Assignment Non-Randomized	None (Open Label)
BNO 1030 Extract (Imupret) in the Treatment of Mild Forms of COVID-19 NCT04797936 [26].	BNO 1030	Phase 4	Ivano-Frankivsk National Medical University Ivano-Frankivsk, Ukraine	18 years to 70 years	Parallel Assignment Randomized	None (Open Label)
Olfactory Disfunction and Co-ultraPEALut NCT04853836 [16].	PEA-LUT	Phase 4	Multicentric Roma, Italy	18 years to 85 years	Parallel Assignment Randomized	Double (Investigator, Outcomes Assessor)
Anosmia Rehabilitation in Patients Post Coronavirus Disease (COVID-19) NCT04374474 Withdrawn (Study withdrawn before any enrollment (site’s research goals adjustments)	Corticosteroid nasal irrigation	Phase 4	St. Joseph’s Health Care London, Ontario, Canada	18 years and older	Parallel Assignment Randomized	None (Open Label)
Olfactory and Neurosensory Rehabilitation in COVID-19-related Olfactory Dysfunction NCT04900415 [27]	Vitamin A	Phase 2	Pamela Youde Nethersole Eastern Hospital Hong Kong, The University of Hong Kong, Queen Mary Hospital, Hong Kong	18 years and older	Parallel Assignment Randomized	Double (Investigator, Outcomes Assessor)