Introduction: Low and High Molecular Weight Hyaluronic Acid
Hyaluronic acid (HA) behaves differently depending on the molecular weight which ranges from 2.5kDa (small molecule HA) to 2 million kDa (polymer HA). Polymer HA has high viscosity and water content and is widely used for treatment of degenerative arthritis and cataract, etc. Various HA types ranging from small molecule to polymer HA, are used in aesthetic treatments for skin rejuvenation. A hybrid form is used in a popular procedure called hydrolifting.1
Small molecule HA is mainly involved in maintaining epidermal homeostasis. In the epidermis, HA exists in the extracellular region due to its negative charge and forms a hydrophilic network that nourishes epidermal keratinocytes, melanocytes, and Langerhans cells. Polymer HA with its excellent water binding capacity acts as a physiological volume expander through its interaction with key dermal ECM components such as proteoglycan and glycoprotein, etc. and helps maintain the structural integrity of the dermis.2
Subcutaneous injection (in hydrolifting) is the most effective method to directly deliver polymer HA to the skin. Injection can be carried out manually or using various injectors. Injection is an invasive method that causes pain and downtime and its effects are short-lived. We will discuss effective techniques of hydrolifting injection and composition as well as case studies in the next article.
In this article, we will look at delivery modalities of small molecule HA, focusing on long-term effects and non-invasive techniques.
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Methods of administering small molecule HA
1. Oral administration (low molecular HA)
2. Transdermal administration (nano-sized topical HA)
3. Transdermal administration (sonophoresis and liposome)
1. Oral administration
Image 1. Oral HA. Iljo Pharmaceuticals’ Prejunex
How efficacious is oral HA? Oral HA can be categorized into two types based on how it is derived; chicken comb and microbial fermentation. In the past oral HA was mostly derived from chicken comb but currently microbial fermentation is preferred for mass production and cost-effectiveness.
Many of my colleagues and I were skeptical of how much oral HA would be absorbed in the body and delivered to the skin. We were particularly doubtful that it would have any therapeutic effect on xeroderma.
-To be continued
