Hydrophilic polyacrylamide gel

Author: Vanessa Ngan, Staff Writer, 2002.

What is hydrophilic polyacrylamide gel?

Hydrophilic polyacrylamide gel (HPG) is a combination of 2.5-5% polyacrylamide, a synthetic polymer, suspended in 95-97.5% apyrogenous water. This is the only injectable implant that remains soft once it has been injected. After injection the water content is absorbed by the body whilst the HPG becomes encapsulated. It remains soft and pliable like the body's own tissue.

HPG products include Aquamid™, Argiform® and DermaLive®. These products are non-toxic, antibacterial, non-sensitising, non-mutagenic, biocompatible and chemically stable.

Polyacrylamides have been available for more than 30 years and are in widespread use in biomedical research and industry. They are also used to make soft contact lenses and are incorporated in many cosmetics, including hair products, body lotions and sunscreens.

Where can HPG implantation be used?

HPG implantation can be used to improve the skin's contour and reduce depressions in the skin due to scars, injury or lines. It is used to correct facial lines and features that could have been treated with collagen replacement therapy or hyaluronic therapy, but where a more permanent solution is wanted.

Facial lines and features that can be corrected using HPG implantation
  • Lip augmentation
  • Cheek remodeling
  • Remodelling of chin clefts
  • Treatment of wrinkles at the commissures of the lips (corners)
  • Nasolabial folds (the lines running from the nose to the corners of the mouth)
  • Treatment of wrinkles between eyebrows
  • Treatment of deep wrinkles, traumatic scars and acne
  • Other types of facial correction

Am I suitable for HPG augmentation?

Almost anybody is suitable for augmentation with HPG. HPG is biologically inert and should be well tolerated by most people. To date, there are no reported cases of sensitivity or HPG causing any type of allergic reaction. Manufacturers claim that the toxic acrylamide monomer, which is found in synthetic polymers of similar types of products, has been removed from HPG.

If you have had a temporary filler injected in the same site, it must have disappeared before you can be treated with HPG. The gel must not be injected in a site where another permanent filler is present.

The gel must not be injected in actively infected areas or areas with an active skin disease such as acne, dermatitisor herpes simplex (cold sores). Some patients may require precautionary antibiotics or antiviral agents prior to and during their HPG treatment.

How is HPG treatment given?

Treatments are carried out at your doctor's rooms.

Procedure for HPG treatments
  1. Wash your face thoroughly with soap and water.
  2. The treatment area is thoroughly cleansed with an antiseptic.
  3. Local anaesthesia may be used.
  4. HPG is injected deep into the skin (in subcutaneous tissue) using a retrograde technique (needle is withdrawn as the HPG is injected).
  5. The treated area is lightly massaged to distribute the gel evenly.
  6. Immediately after injection the site may be red and swollen. This usually minimal and subsides after 20minutes. Any persisting redness, bruising or swelling usually disappears within two weeks.
  7. Do not apply make up or touch the injection site for 2 days.
  8. A top-up treatment may be required two weeks or so later.

How long do HPG implants last?

HPG implantation is considered permanent. It cannot be reabsorbed into the body. However, as time goes on skin ages and underlying tissue and muscle will change position and shape, creating new wrinkles and imperfections.

Are there any side effects from HPG therapy?

HPG therapy is generally very well tolerated. At the time of treatments most patients report minor discomfort. This may be minimized by the use of a local anaesthetic. Immediately after treatment the area may be red, swollen and tender, this usually improves within a few days. Inform your doctor if you develop pain, redness or swelling after this. These reactions are usually self-limiting, but your doctor will advise you if you need any further treatment.

Very rarely, granulomas (persistent inflammatory lumps) have been reported to arise at the site of injection weeks or months after treatment.

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