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Biomedical subjects

Peter C Panus

Publications and source records attributed to Peter C Panus.

5 recordsLinked to original sources
PubMed2006

Lidocaine iontophoresis mediates analgesia in lateral epicondylalgia treatment.

BACKGROUND AND PURPOSE: Iontophoresis transcutaneously delivers anti-inflammatory and analgesic drugs for the treatment of musculoskeletal dysfunction. Lidocaine is a local anaesthetic with analgesic but no anti-inflammatory properties. The purpose of this investigation was to examine the clinical use of lidocaine iontophoresis-mediated analgesia in a larger treatment algorithm for five patients with lateral humeral epicondylalgia. METHOD: The investigation was a case series design of five subjects, aged 52 (+/- 6) years, with epicondylalgia of 12-393 days' duration. At each treatment session, the patients received cryotherapy, cross-fibre massage and passive stretch. Between sessions analgesia was provided by an 80 mA-min low-current, long-duration lidocaine iontophoresis (LI) over a 24-hour period. Patients were treated on an every-other-day basis for a total of three treatment sessions. Clinical improvements were determined by triplicate measurements of dolorimetric force over the affected epicondyle prior to treatment 1 (baseline), prior to sessions 2 and 3, and one week following the last session. RESULTS: Patients demonstrated an increasing tolerance to dolorimetric force application prior to the next session. The force values prior to session 2 (3.1 (+/- 1.1) Newton (N)) and one week following the third session (3.4 (+/- 0.5) N) were significantly improved from the baseline values (2.1 (+/- 0.9) N). CONCLUSIONS: Pain associated with lateral epicondylalgia decreased, and function improved in all patients at the final measurement. One patient returned during the 90-day follow-up period to seek additional medical attention. This investigation documents the potential for analgesia provided by LI in the rehabilitation process of musculoskeletal dysfunction.

Algorithms↗
PubMed2004

The influence of voluntary tonic EMG level on the vestibular-evoked myogenic potential.

Vestibular-evoked myogenic potentials (VEMPs) are proposed as a reliable test to supplement the current vestibular test battery by providing diagnostic information about saccular and/or inferior vestibular nerve function. VEMPs are short-latency electromyograms (EMGs) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid muscle. VEMP amplitude is influenced by the EMG level, which must be controlled. This study examined the ability of subjects to achieve the EMG target levels over a range of target levels typically used during VEMP recordings. In addition, the influence of target EMG level on the latency and amplitude of the click- and tone-evoked VEMP was examined. The VEMP amplitude increased as a function of EMG target level, and the latency remained constant. EMG target levels ranging from 30 microV to 50 microV are suggested for clinical application of the VEMP.

Acoustic Stimulation↗
PubMed2003

Effects of iontophoresis current magnitude and duration on dexamethasone deposition and localized drug retention.

BACKGROUND AND PURPOSE: Iontophoresis is a process that uses bipolar electric fields to propel molecules across intact skin and into underlying tissue. The purpose of this study was to describe and experimentally examine an iontophoresis drug delivery model. SUBJECTS AND METHODS: A mechanistic model describing delivery was studied in vitro using agarose gels and was further tested in vivo by evaluation of cutaneous vasoconstriction following iontophoresis in human volunteers. RESULTS: In vitro cathodic iontophoresis at 4 mA and 0.1 mA each delivered dexamethasone/dexamethasone phosphate (DEX/DEX-P) from a 4-mg/mL donor solution to a depth of 12 mm following a 40 mA minute stimulation dosage. Delivery of DEX/DEX-P to at least the depths of the vasculature in humans was confirmed by observation of cutaneous vasoconstriction. This cutaneous vasoconstriction was longer lasting and greater in magnitude when using low-current, long-duration (approximately 0.1 mA) iontophoresis compared with equivalent dosages delivered by higher-current, shorter-duration (1.5-4.0 mA) iontophoresis. DISCUSSION AND CONCLUSION: From data gathered with the gel model, the authors developed a model of a potential mechanism of drug depot formation following iontophoresis. The authors believe this drug depot formation to be due to exchange of drug ions for chloride ions as the ionic current carriers. Furthermore, diffusion, not magnitude of current, appears to govern the depth of drug penetration. Although the authors did not address the efficacy of the drug delivered, the results of human experiments suggest that current magnitude and duration should be considered as factors in treating musculoskeletal dysfunctions with iontophoresis using DEX/DEX-P at a concentration of 4 mg/mL.

Administration, Cutaneous↗
PubMed2002

Failure to detect dexamethasone phosphate in the local venous blood postcathodic lontophoresis in humans.

STUDY DESIGN: A single-blind, 2-factor (4 treatments by 8 time points) repeated-measures study design. OBJECTIVE: To analytically determine dexamethasone and dexamethasone phosphate concentrations in plasma derived from proximal effluent venous blood, following cathodic iontophoresis. METHODS AND MEASURES: Six volunteers received the following dexamethasone phosphate (2.5 ml, 4 mg/ml) treatments to their wrists on separate occasions: cathodic iontophoresis (4 mA, 10 minutes or 4 mA, 20 minutes), passive application (10 or 20 minutes). Plasma samples from the ipsilateral antecubital vein were obtained 10 minutes prior to and half way through the treatment (5 or 10 minutes), at the end of the treatment (10 or 20 minutes), and posttreatment (15, 30, 60, 90, and 120 minutes). The present investigation examined: (1) the sensitivity and linearity of extraction and analysis of dexamethasone and dexamethasone phosphate; (2) the necessity for determining both; and (3) the plasma levels from proximal effluent venous blood following cathodic iontophoresis. RESULTS: The aggregate (n = 18) of the 6-point standard curves were linear for dexamethasone (r > 0.974) and dexamethasone phosphate (r > 0.829). In vitro dephosphorylation of dexamethasone phosphate to dexamethasone occurred in plasma at 37 degrees C and during freeze-thaw. Measurable dexamethasone or dexamethasone phosphate concentrations were absent at all time points and under all conditions in the human subjects. CONCLUSIONS: These results demonstrate the sensitivity of the current assay and the need for evaluating both forms of the drug, as in vitro dephosphorylation results in the presence of dexamethasone and dexamethasone phosphate in samples. Absence of measurable dexamethasone or dexamethasone phosphate in the proximal effluent venous blood may require re-evaluation of the extent of drug delivery during the clinical iontophoresis of dexamethasone phosphate.

Adult↗