Applications of iontophoresis in sports medicine

Jean Philippe Sylvestre

Research output: ThesisDoctoral Thesis

Abstract

In this thesis, two potential applications of transdermal iontophoresis in the field of sports medicine were studied: (1) the local delivery of dexamethasone phosphate (Dex-Phos), a corticosteroid used to treat musculoskeletal inflammation, and (2) the extraction of systemic amino acids (AAs), potential biological markers of fatigue in athletes. The iontophoretic delivery of Dex-Phos was studied, in vitro, in order to evaluate the effects of competing ions and electroosmosis, and identify the optimal conditions for its delivery. The iontophoretic extraction of AAs from the skin was first studied in vitro, before evaluating the method in a group of human volunteers. Dex-Phos was best delivered by iontophoresis from the cathode in absence of background electrolyte in the drug solution. In this situation, the delivery of Dex-Phos is limited principally by the competition with counter-ions (mainly Na+) present subdermally and the small mobility of the drug inside the membrane. The accumulation of Cl-, released by the Ag/AgCl cathode in the drug solution during current passage, can also reduce Dex-Phos delivery. The extraction of zwitterionic AAs from the skin during iontophoresis was highly influenced by their presence in the outermost layer of the skin, the stratum corneum (SC). In the pig skin model, the amount of the AAs extracted during a short extraction period (1 hour) correlated with their abundance in the SC. Once this ‘reservoir’ was emptied (after ~3 hours of iontophoresis), the subdermal compartment could be sampled, suggesting that the method could be used to monitor systemic levels of AAs. The experiments in human volunteers revealed, however, that a 4-hour iontophoretic extraction period was insufficient to deplete the AAs SC ‘reservoir’. It follows that the method can be used to evaluate the abundance of AAs in the SC, but is unpractical for the clinical monitoring of their systemic levels.
LanguageEnglish
QualificationPh.D.
Awarding Institution
  • University of Bath
Supervisors/Advisors
  • Guy, Richard, Supervisor
  • Delgado-Charro, Maria, Supervisor
Award date1 Nov 2007
StatusPublished - 2007

Fingerprint

dexamethasone 21-phosphate
Iontophoresis
Sports Medicine
Amino Acids
Cornea
Skin
Volunteers
Electrodes
Pharmaceutical Preparations
Electroosmosis
Ions
Athletes
Electrolytes
Fatigue
Adrenal Cortex Hormones
Swine
Biomarkers
Inflammation
Membranes

Keywords

  • clinical monitoring
  • corticosteroids
  • iontophoresis
  • amino acids
  • dexamethasone phosphate
  • drug delivery
  • marker of fatigue
  • skin

Cite this

Applications of iontophoresis in sports medicine. / Sylvestre, Jean Philippe.

2007.

Research output: ThesisDoctoral Thesis

Sylvestre, JP 2007, 'Applications of iontophoresis in sports medicine', Ph.D., University of Bath.
Sylvestre, Jean Philippe. / Applications of iontophoresis in sports medicine. 2007.
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AB - In this thesis, two potential applications of transdermal iontophoresis in the field of sports medicine were studied: (1) the local delivery of dexamethasone phosphate (Dex-Phos), a corticosteroid used to treat musculoskeletal inflammation, and (2) the extraction of systemic amino acids (AAs), potential biological markers of fatigue in athletes. The iontophoretic delivery of Dex-Phos was studied, in vitro, in order to evaluate the effects of competing ions and electroosmosis, and identify the optimal conditions for its delivery. The iontophoretic extraction of AAs from the skin was first studied in vitro, before evaluating the method in a group of human volunteers. Dex-Phos was best delivered by iontophoresis from the cathode in absence of background electrolyte in the drug solution. In this situation, the delivery of Dex-Phos is limited principally by the competition with counter-ions (mainly Na+) present subdermally and the small mobility of the drug inside the membrane. The accumulation of Cl-, released by the Ag/AgCl cathode in the drug solution during current passage, can also reduce Dex-Phos delivery. The extraction of zwitterionic AAs from the skin during iontophoresis was highly influenced by their presence in the outermost layer of the skin, the stratum corneum (SC). In the pig skin model, the amount of the AAs extracted during a short extraction period (1 hour) correlated with their abundance in the SC. Once this ‘reservoir’ was emptied (after ~3 hours of iontophoresis), the subdermal compartment could be sampled, suggesting that the method could be used to monitor systemic levels of AAs. The experiments in human volunteers revealed, however, that a 4-hour iontophoretic extraction period was insufficient to deplete the AAs SC ‘reservoir’. It follows that the method can be used to evaluate the abundance of AAs in the SC, but is unpractical for the clinical monitoring of their systemic levels.

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