title: Relative acoustic transmission of topical preparations used with therapeutic ultrasound.
abstract: OBJECTIVE
  To determine the relative acoustic transmission allowed by various preparations at 1MHz and 3MHz ultrasound (US) frequencies.
  
  
  METHODS
  Bench-top laboratory study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  No human or animal participants were used.
  
  
  METHODS
  We administered continuous US through various over-the-counter preparations at 1.2W/cm(2) at both 1MHz and 3MHz frequencies for 30 seconds and measured the acoustic output.
  
  
  METHODS
  Percentage of transmission of energy relative to commercial US gel. Planned observational comparisons were made at both 1MHz and 3MHz frequencies. Topical agents were categorized as either gel-based or cream-based preparations.
  
  
  RESULTS
  Transmission of gel-based preparations (1MHz and 3MHz): Arnica gel (97% and 110%), Biofreeze (60% and 79%), Capzasin (70% and 93%), Cobroxin (76% and 91%), and Solarcaine (70% and 101%). Cream-based preparations (1MHz and 3MHz): Arnica cream (67% and 74%), Australian Dream (54% and 80%), Bengay (37% and 55%), MediPeds Footcare (126% and 101%), Neuragen PN (76% and 90%), Octogen (38% and 47%), and Thera-Gesic (52% and 73%).
  
  
  CONCLUSIONS
  Topical agents suspended in aqueous gels are generally more effective in transmitting US energy, while many cream-based agents are less effective, particularly at 1MHz frequency. Many agents that are commonly used to provide a sensory effect, such as topical analgesic creams, may block US transmission. Agents that reduce US transmission may lead to poor phonophoresis results and are likely to minimize the therapeutic effects of US.
authors.affiliation: Morgan State University, Baltimore, MD; Kinesiology Program, Department of Human Services, Curry School of Education, University of Virginia, Charlottesville, VA.
authors.forename: S Andrew
authors.initials: SA
authors.lastname: Cage
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Rupp
authors.forename: John C
authors.initials: JC
authors.lastname: Castel
authors.forename: Ethan N
authors.initials: EN
authors.lastname: Saliba
authors.forename: Jay
authors.initials: J
authors.lastname: Hertel
authors.forename: Susan A
authors.initials: SA
authors.lastname: Saliba
mesh_terms: D000162:Acoustics; D000279:Administration, Cutaneous; D000700:Analgesics / Q000008:administration & dosage; D018650:Arnica; D004366:Nonprescription Drugs; D015612:Phonophoresis; D014464:Ultrasonic Therapy
chemical_list: D000700:Analgesics; D004366:Nonprescription Drugs
keywords: Administration, cutaneous; Administration, topical; Analgesics; Phonophoresis; Rehabilitation; US; ultrasound