Topical Versus Injection PRP for Olfactory Dysfunction

NCT07151703 | Not Yet Recruiting Phase 3 DMC

• 2 other identifiers: 2025-06-010Cafter funding being approved
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to determine whether two different delivery methods of autologous platelet-rich plasma (PRP) can improve olfactory function in adults with persistent olfactory dysfunction lasting more than three months. The main questions it aims to answer are:

1. 1.Does carrier-assisted topical application of PRP lead to comparable or better improvement in smell function than intranasal injection of PRP?
2. 2.Which method provides greater patient comfort and fewer adverse effects?
3. 3.Receive a single PRP treatment delivered either by injection or via a PRP-soaked carrier placed into the olfactory cleft.
4. 4.Continue daily olfactory training for three months following the intervention.
5. 5.Undergo smell testing (Sniffin' Sticks) before and after treatment and complete quality-of-life questionnaires.

Conditions

Olfactory Dysfunction; Anosmia; Hyposmia

Keywords

Anosmia; Hyposmia; Platelet-Rich Plasma (PRP); Intranasal Injection; Randomized Controlled Trial

Outcome Measures

Primary Outcomes (1)

• Sniffin' Sticks Olfactory Test

  The Sniffin' Sticks test (Burghart Messtechnik GmbH, Holm, Germany) comprises three subtests for odor detection threshold (T), odor discrimination (D), and odor identification (I). This test employs odor-containing felt-tip pens, which are presented to participants to evaluate their olfactory performance. In the detection threshold subtest, we employed an adaptive staircase procedure based on a three-alternative forced-choice format. Participants were tasked with differentiating a stick with a rose-like aroma (phenylethyl alcohol) from two blank sticks. Odor discrimination was assessed using 16 pen triplets, two of which contained identical odors and one stick contained a different odor. Participants were tasked with identifying the odd one out. In the odor identification subtest, participants were tasked with naming 16 common odors by selecting appropriate terms from a set of four descriptors per odor. The scores from each subtest were combined into a composite TDI score.

  pre-intervention and at 1 and 3 months (may extend to 6 and 12 months) post-intervention

Secondary Outcomes (9)

• Procedure-related pain evaluation

  during the procedure and up to 2 weeks post-intervention

• Retronasal Olfactory Test

  pre-intervention and at 3 months post-intervention

• Visual Analogus Scale for olfaction

  pre-intervention and at 1 and 3 months (may extend to 6 and 12 months) post-intervention

• Questionnaire of Olfactory Disorders (QOD)

  pre-intervention and at 1 and 3 months (may extend to 6 and 12 months) post-intervention

• Beck Depression Inventory (BDI)

  pre-intervention and 3 months post-intervention

Study Arms (2)

Intranasal PRP injection

EXPERIMENTAL

Participants in this arm will receive an intranasal injection of autologous platelet-rich plasma (PRP) into the olfactory cleft. The procedure will be conducted under local anesthesia using endoscopic guidance. All participants will also perform standardized daily olfactory training for three months following the intervention.

Procedure: Intranasal Injection of Autologous PRP; Combination Product: platelet-rich plasma; Device: olfactory training

Topical PRP application arm

EXPERIMENTAL

Participants in this arm will receive a topical application of autologous PRP delivered via PRP-soaked absorbable material (Gelfoam) placed into the olfactory cleft. No needle will be used. The placement will be guided by nasal endoscopy under local anesthesia. Daily olfactory training will be continued for three months post-application.

Procedure: Carrier-Assisted Topical Application of Autologous PRP; Combination Product: platelet-rich plasma; Device: olfactory training

Interventions

Intranasal Injection of Autologous PRP PROCEDURE

Under topical anesthesia and decongestion, approximately 1 mL of freshly prepared autologous platelet-rich plasma will be injected into multiple sites of the olfactory cleft mucosa bilaterally using a 25-gauge needle under endoscopic guidance. Single treatment session.

Intranasal PRP injection

Carrier-Assisted Topical Application of Autologous PRP PROCEDURE

Four pieces of sterile, bioabsorbable carrier (Gelfoam sponge) will be soaked with approximately 5 mL of freshly prepared autologous platelet-rich plasma. Under endoscopic guidance, two pieces will be placed gently into each olfactory cleft, ensuring contact with the olfactory mucosa. Carriers will remain briefly to allow PRP diffusion before dissolving naturally or being removed. Single treatment session.

Topical PRP application arm

platelet-rich plasma COMBINATION_PRODUCT

This study adopts a fully automated, closed-system PRP preparation technique to ensure the stability of the blood product. A total of 60 mL of whole blood is drawn and processed using the Phoenix Q1 centrifuge (TFDA Medical Device Manufacturing License No. 004461) for blood component separation in a closed, sterile environment. An optical sensor identifies and automatically collects the buffy coat layer (rich in platelets and monocytes), yielding approximately 6 mL of autologous platelet-rich plasma (PRP). The centrifugation and PRP collection process takes about 5 minutes. Compared with traditional methods requiring manual identification and collection, this approach enhances the precision and safety of centrifugation-based preparation.

Intranasal PRP injection; Topical PRP application arm

olfactory training DEVICE

Participants will perform olfactory training for 12 weeks following the PRP intervention. Training is conducted twice daily using four odor bottles containing standardized odorants from Sigma-Aldrich (Germany): lemon (citronellal, #27470), rose (phenylethanol, #77861), clove (eugenol, #W246700), and eucalyptus (eucalyptol, #C80601). Each odor is sniffed gently for about 20 seconds, with a 20-second pause between bottles. Participants will record the perceived intensity of each odor in a training diary after every session.

Intranasal PRP injection; Topical PRP application arm

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Aged between 18 and 80 years, regardless of sex
• Subjective complaint of olfactory dysfunction with confirmed hyposmia or anosmia based on standardized olfactory testing
• History of at least 3 months of prior olfactory training but with persistent olfactory complaints

You may not qualify if:

• Congenital anosmia
• Diagnosed neurological or structural brain abnormalities (e.g., brain tumor, major head trauma, stroke) with low likelihood of olfactory recovery
• Inability or unwillingness to comply with study procedures or follow-up assessments

Sponsors & Collaborators

• Taipei Veterans General Hospital, Taiwan: lead

Study Sites (1)

Taipei Veterans General Hospital

Taipei, 112201, Taiwan

Location

Related Publications (5)

• Bae AY, Kim DH, Hwang SH. Efficacy of Platelet-Rich Plasma in the Treatment of Persistent Olfactory Impairment After COVID-19: A Systematic Review and Meta-Analysis. J Rhinol. 2024 Mar;31(1):1-7. doi: 10.18787/jr.2024.00006. Epub 2024 Mar 31.

  PMID: 39664044 BACKGROUND

• Duffy A, Naimi B, Garvey E, Hunter S, Kumar A, Kahn C, Farquhar D, D'Souza G, Rawson N, Dalton P, Toskala E, Rabinowitz M, Rosen M, Nyquist G, Rosen D. Topical platelet-rich plasma as a possible treatment for olfactory dysfunction-A randomized controlled trial. Int Forum Allergy Rhinol. 2024 Sep;14(9):1455-1464. doi: 10.1002/alr.23363. Epub 2024 May 9.

  PMID: 38722276 BACKGROUND

• Jiang RS, Chiang YF. The Effect of Platelet-Rich Plasma and Hyaluronic Acid Nasal Injections in the Treatment of Traumatic Olfactory Dysfunction. Ear Nose Throat J. 2024 Oct 15:1455613241291710. doi: 10.1177/01455613241291710. Online ahead of print.

  PMID: 39404838 BACKGROUND

• Lechien JR, Le Bon SD, Saussez S. Platelet-rich plasma injection in the olfactory clefts of COVID-19 patients with long-term olfactory dysfunction. Eur Arch Otorhinolaryngol. 2023 May;280(5):2351-2358. doi: 10.1007/s00405-022-07788-8. Epub 2022 Dec 15.

  PMID: 36520209 BACKGROUND

• Yan CH, Mundy DC, Patel ZM. The use of platelet-rich plasma in treatment of olfactory dysfunction: A pilot study. Laryngoscope Investig Otolaryngol. 2020 Feb 21;5(2):187-193. doi: 10.1002/lio2.357. eCollection 2020 Apr.

  PMID: 32337347 BACKGROUND

MeSH Terms

Conditions

Anosmia

Interventions

Olfactory Training

Condition Hierarchy (Ancestors)

Olfaction Disorders; Sensation Disorders; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Therapeutics

Central Study Contacts

Dr. Yun-Ting Chao Principal Investigator (Attending Physician and Head of Dep.), PhD

CONTACT

886-2-2875-7337; yunting001@gmail.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Masking Details: Both participants and outcome assessors were blinded to the group assignment to minimize expectation bias. Interventions were prepared using an identical procedure to ensure blinding. The principal investigator, who was responsible for administering the intervention, was aware of group allocation. However, participants and outcome assessors had no access to allocation information throughout the study.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Dr.

Model Details: Parallel two-arm design with participants randomly assigned to either carrier-assisted topical PRP application or intranasal PRP injection. Each participant receives only one type of intervention throughout the study.

Study Record Dates

• First Submitted: August 16, 2025
• First Posted: September 3, 2025
• Study Start: October 1, 2025
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2028
• Last Updated: September 3, 2025

Record last verified: 2025-08

Locations

TW (1)