Topical Transdermally Delivered Lidocaine and Benzocaine Compared to Compounded Lidocaine/Tetracaine During Microfocused Ultrasound With Visualization Treatment.

OBJECTIVE: The efficacy of various pre-medication strategies for comfort management during microfocused ultrasound with visualization (MFU-V) treatment has not been studied. The present objective was to compare 2 topical analgesics (lidocaine 4% and benzocaine 20%) formulated with a novel transdermal delivery system with compounded lidocaine 23%/tetracaine 7% (23/7) to mitigate discomfort during MFU-V treatment. METHODS: This was a randomized, double-blinded, split-face study. One hour before MFU-V, subjects (N=14 females) received 50 mg IM meperidine/25 mg IM promethazine/5 mg oral diazepam. Fifteen minutes before treatment, 1 side of the face was treated with 1 application of 4% lidocaine, followed by 1 application of 20% benzocaine; the contralateral side was treated with 2 applications of 23/7 (to maintain blinding). Numbness was assessed by blinded evaluator (scale: 1=completely numb to 4=not numb) pre-treatment. Subject pain scores (scale: 0=no pain to 10=worst pain) were collected post-treatment. Adverse events and subjective clinician measures were also assessed. RESULTS: Mean subject pain scores for 23/7 and lidocaine 4%/benzocaine 20% were 5.6 and 5.7, respectively. Mean numbness scores were similar for 23/7 (2.5) and lidocaine 4%/benzocaine 20% (3.0). Clinicians rated both products as "very easy" to apply. For lidocaine 4%/benzocaine 20%, 7.1% of subjects required no pauses during treatment, vs 14.3% for 23/7. However, more subjects required 4+ pauses with 23/7 (21.4% vs 7.1%). Lidocaine 4%/benzocaine 20% was preferred by 78.5% of subjects; 35.7% rated lidocaine/benzocaine 20% 4% as "Very Effective" vs 7.1% for 23/7. No adverse events were reported. CONCLUSIONS: Lidocaine 4% and benzocaine 20% formulations utilizing a novel transdermal delivery system perform similarly to compounded lidocaine 23%/tetracaine 7% for discomfort mitigation during MFU-V treatment. More subjects preferred lidocaine 4%/ benzocaine 20% and rated it as "very effective" vs the compounded product. Fewer treatment pauses due to patient discomfort when using the lidocaine 4%/benzocaine 20% may translate to time efficiency. J Drugs Dermatol. 2018;17(7):729-734.

Measurement of protein turnover rates by heavy water labeling of nonessential amino acids.

In vivo measurements of protein synthesis using isotope-labeled amino acids (AAs) are hampered by the heterogeneity of AA pools and, for slow turnover proteins, the difficulty and expense of long-term labeling. Continuous oral heavy water (2H2O) labeling can safely maintain stable body water 2H enrichments for weeks or months. 2H is metabolically incorporated into C-H bonds of nonessential AAs (NEAAs) and hence into proteins. No posttranslational label exchange occurs, so 2H incorporation into protein NEAAs, in principle, reports on protein synthesis. Here, we show by mass isotopomer distribution analysis (MIDA) of 2H2O-labeled rodent tissue proteins that metabolic 2H flux into C-H bonds of Ala, Gly, or Gln used for protein synthesis is nearly complete. By 2H2O labeling of rodents, turnover of bone and muscle mixed proteins was quantified and stimulation of liver collagen synthesis by CCl4 was detected. Kinetics of several human serum proteins were also measured, reproducing published t1/2 estimates. Plateau enrichments in Ala varied among different proteins. Moderate amounts of protein, isolated chromatographically or electrophoretically, sufficed for kinetic analyses. In conclusion, 2H2O labeling permits sensitive, quantitative, operationally simple measurements of protein turnover in vivo by the rise-to-plateau approach, especially for proteins with slow constitutive turnover.

Heavy water labeling of keratin as a non-invasive biomarker of skin turnover in vivo in rodents and humans.

Measurement of skin turnover has been problematic in humans. Heavy water (2H2O) labeling has recently been developed as a safe, simple method to study in vivo kinetics of many biosynthetic processes, including DNA and protein synthesis. Here, we apply this approach to the measurement of 2H incorporation into skin keratin and show close agreement between keratin and keratinocyte turnover data in the epidermis of rodents. Elevated turnover rates of both keratin and keratinocytes were observed in the epidermis of the flaky skin mouse, although topical treatments effective in human psoriasis had no effect on either turnover rate in these mice. In humans, keratin turnover was monitored non-invasively by serial tape stripping during and after 2H2O labeling. Kinetic data were consistent with previous estimates of epidermal turnover, with a lag time of 18 days before label appeared at the skin surface and a transit time of 4-5 weeks. Variability in skin keratin turnover rates was present among healthy individuals. In summary, 2H2O labeling of skin keratin represents a non-invasive approach for assessing skin turnover dynamics in pre-clinical models and in human subjects.

Development of a novel method for measuring in vivo breast epithelial cell proliferation in humans.

Cell proliferation plays an important role in all stages of carcinogenesis. Currently, no safe, direct, in vivo method of measuring breast epithelial cell (BEC) proliferation rates in humans exists. Static immunohistochemical markers of cell proliferation, such as Ki-67 and PCNA indices, have technical limitations including high inter-lab variability, inaccuracy in the presence of agents that cause G1/S cell cycle block and inadequate sensitivity in post-menopausal women with low BEC proliferation rates. We describe here a safe, direct method of measuring BEC proliferation rates in vivo in women using heavy water ((2)H(2)O) labeling coupled with mass spectrometric analysis. Proliferation of normal and tumor BEC was measured from breast tissue biopsies in women undergoing mastectomy (n = 11) and normal BEC from healthy volunteers (n = 16). Women took heavy water (50-150 ml per day) for 1-4 weeks. Pre-menopausal women had significantly higher proliferation rates than post-menopausal women (0.7 +/- 0.1 versus 0.2 +/- 0.1 new cells per day, respectively), and tumor BEC had different proliferation rates than normal BEC from the same breast. The method is analytically reproducible and remains sensitive in the range of low proliferation rates. In summary, this novel method of measuring BEC proliferation in vivo holds promise for assessing the effects of anti-proliferative chemopreventive and chemotherapeutic agents.