Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets.

Normal values of plantar pressure measurements determined using the EMED-SF system

Plantar pressure-measurement technology is being increasingly used by podiatric physicians and surgeons in both clinical practice and research. The authors present normal reference-range values for peak pressure, mean pressure, and pressure-time integral obtained from 30 healthy subjects using a two-step recording technique and the EMED-SF system, as background for proposed clinical trials. Normative data of this type are essential for clinical practice in the comparison of plantar pressure-measurement values of individual patients with those of normal, asymptomatic feet.

The effect of hallux valgus correction on chronic plantar ulceration. A case report

Plantar pressure-measurement technology may provide the clinician with valuable objective information for monitoring the effects of therapeutic intervention on the foot. The use of this technology is described in the preoperative and postoperative assessment of a patient undergoing hallux valgus surgery for the treatment of a chronic neuropathic skin ulcer over the medioplantar aspect of her first metatarsophalangeal joint.

Review of radiographic measurements following Austin bunionectomy

This study compared preoperative and postoperative results for selected radiographic measurements of 30 patients undergoing the modified Austin bunionectomy procedure for the correction of hallux abducto valgus. Significant reductions in all postoperative radiographic values were demonstrated, including hallux abductus angle, metatarsus primus adductus angle, tibial sesamoid position, and first metatarsal protrusion distance.