As defined by Wikipedia, Collagen "is the main protein of connective tissue in animals and the most abundant protein in mammals." According to the American Academy of Dermatology, this soft tissue can be injected into the skin to improve the appearance of fine lines and wrinkles, to plump lips, fill hollow cheeks, improve scars, and elevate deep folds. Appropriate for individuals who are looking to improve their appearance but prefer not to undergo major surgery, statistics provided by the American Society of Plastic Surgeons estimates that over 267,339 Americans had collagen injections in 2006 alone.

This article examines the differences between human and bovine collagen, the only two types of collagen that are FDA approved for use in some of today's most popular dermal fillers. It also provides an overview of the six collagen-based injectables currently available.

Bovine Collagen

Extracted from cow skin, then purified, sterilized and processed into liquid form for injection under the skin, the effects of treatment with bovine collagen can last for up to 1 year. Inamed Aesthetics has manufactured bovine collagen for use as a dermal filler under the brand names Zyderm I, Zyderm II and Zyplast, According to Medical News Today, a website devoted to providing the latest news in the field of medicine, "bovine collagen has been the undisputed filler of choice for the treatment of facial wrinkles since injectable skin fillers were introduced in the 1970s."

Reports provided by the New Zealand Dermatological Society, explain, "since injectable bovine collagen is derived from cows it may cause allergic reactions. Approximately 3% of the (global) population is allergic to bovine collagen; these individuals should not receive these implants." In addition to this risk, the article continues, "there have also been reports of connective tissue disease arising for the first time after bovine collagen injections. However a connection between the injections and the connective tissue disease has not been established." In order to ensure safety, patients planning treatment with a bovine collagen product are required to take an allergy test approximately 1 month prior to the expected procedure date. Although treatment with human collagen is quickly becoming the choice of surgeons, some patients prefer bovine collagen due to cost savings and market longevity.

Zyderm I

FDA approved in 1981 for use in aesthetic tissue augmentation, Zyderm I consists of 35 mg/ml of bovine collagen dispersed in a saline solution containing 0.3% of the anesthetic lidocaine. Most effective in the treatment of fine lines, wrinkles, and shallow scars as well as on the thin-skinned areas of the face, Zyderm I is best used to correct the thin lines which develop around the eyes and mouth. Because the body reabsorbs the saline in this product, physicians purposefully overfill the treatment areas by 200%. The resultant redness, puffiness and swelling which ensues usually subsides within a few days following the procedure. The effects of treatment with Zyderm I, according to emedicine.com, an online database of clinical research, can last anywhere from 6 weeks to 3 months

Zyderm II

Zyderm II, also approved by the FDA in 1981, is most effective in the treatment of moderate lines, wrinkles and scars. Consisting of 65 mg/ml of purified bovine collagen dispersed in a saline solution containing 0.3% lidocaine, Zyderm II is best used to treat areas such as the glabella (the space between the eyebrows) and the nasolabial folds (the lines that extend from the nose to the edge of the mouth). Given the greater concentration of collagen and decreased amount of saline found in Zyderm II, physicians only need to overfill the treated area by 150%. Like Zyderm I, although redness and puffiness are to be expected, these side effects usually resolve within a few days as the body absorbs the excess saline solution. Effects of treatment with Zyderm II, according to emedicine.com, generally last for 4 to 5 months.

Zyplast

Approved by the FDA in 1985, Zyplast is used to treat pronounced lines and wrinkles, scars, and thicker-skinned areas. This makes it more effective than Zyderm I and Zyderm II in the correction of deeper wrinkles and imperfections. Composed of purified bovine collagen cross linked with glutaraldehyde (preservative) and dispersed in a saline solution containing 0.3% of the anestheic lidocaine, overcorrection with Zyplast is not necessary. As a result, the amount of swelling a patient experiences following Zyplast injections may be slightly less than that experienced when being treated with Zyderm I or Zyderm II. The effects of treatment with Zyplast, according to emedicine.com, can last anywhere from 9 months to a year.

Zyderm I, Zyderm II and Zyplast are the most commonly used dermal fillers in the United States, and can be integrated into a simple office visit for the patient requesting dermal augmentation. According to emedicine.com, "frequent maintenance is necessary and the question always arises whether it is cost effective. The filling agent is technique dependent for longer lasting results, proportional to the clinician's ability to place the collagen correctly. Adverse reactions have been noted including allergic reactions, hypersensitivity reactions with Zyderm I and II, and avascular necrosis (tissue death) occurring with Zyplast, particularly in the glabella and on the nose. Although these complications are rare, they have been reported and proper allergy testing must be performed for each patient."

Human Collagen

Prior to use in aesthetic augmentation, human collagen, according to emedicine.com, is “harvested from cadaver skin specimens from the American Association of Tissue Banks (AATB)," then screened and sterilized for injection. Manufactured by Inamed Aesthetics, CosmoDerm I, Cosmodern II, and CosmoPlast were FDA approved in 2003. According to the Canadian Society of Aesthetic Plastic Surgery, these three products "are the only FDA-approved, commercially available dermal fillers in the world that contain natural human collagen. Unlike other dermal fillers, CosmoDerm and CosmoPlast do not require a pre-treatment skin test. Treatment with CosmoDerm and CosmoPlast is a safe and effective way to aid in the correction of facial wrinkles, glabellar frown lines, nasolabial folds, vermilion borders, distensible scars and other soft tissue deficiencies. In addition, CosmoDerm and CosmoPlast are formulated with an anesthetic to minimize patient discomfort. CosmoDerm and CosmoPlast provide immediate results in just one visit."

Unlike treatment with bovine collagen, there is no risk of an allergic reaction when being treated with products derived from human collagen. Treatment with human collagen typically requires 2 to 3 injections spaced out over a 2 to 4 week period in order to achieve a 1 to 2 year correction.

CosmoDerm I

According to Inamed Aesthetics' website, CosmoDerm was approved by the FDA in 2003, and was designed especially for people with fine wrinkles or scars that are not very deep. It can be particularly effective in smoothing delicate frown and smile lines, as well as the fine creases that develop at the corners of the eyes and above and below the lips. It can also help correct certain kinds of scars. Composed of 35 mg/mL of purified human-based collagen dispersed in a saline solution containing lidocaine, CosmoDerm I is especially effective for treatment of the thin-skinned areas of the face. The effects of injections with CosmoDerm I can be expected to last approximately 3 months.

CosmoDerm II

FDA approved in March 2003 for the correction of soft tissue contour defects, such as wrinkles and acne scars, CosmoDerm II is made of 65mg/ml of human collagen dispersed in a saline solution mixed with the anesthetic lidocaine. Containing almost twice the amount of collagen as CosmoDerm I, CosmoDerm II is more effective in the treatment of moderate to deep lines and wrinkes. Furthermore, because this greater concentration of collagen creates a thicker emulsion, CosmoDerm II provides more support to the desired augmentation. As a result, CosmoDerm II has been found to be more effective in lip enhancement or correction than CosmoDerm I. The effects of treatment with CosmoDerm II can be expected to last for up to 3 months.

CosmoPlast

CosmoPlast is used to treat depressions requiring a stronger treatment material. Approved by the FDA in March 2003, CosmoPlast is most effective in the treatment of pronounced wrinkles and scars and for areas such as the corners of the mouth upon which more stress is exerted. Composed of 35 mg/mL of purified human-based collagen, cross-linked with glutaraldehyde dispersed in a saline solution containing lidocaine, the effects of treatment with CosmoPlast can be expected to last for up to 6 months.

Although CosmoDerm I, CosmoDerm II, and CosmoPlast can be safely used in conjunction with one another, according to the manufacturer, treatment with CosmoDerm I, CosmoDerm II and CosmoPlast "should be limited to 30 mL over a 1-year period. Use of CosmoDerm 2 should be limited to 15 mL over a 1-year period. Likewise, the use of CosmoPlast should also be limited to 30 mL over a 1-year period. The combination of CosmoDerm 1 and CosmoDerm 2, or of CosmoDerm in conjunction with CosmoPlast should be limited to 30 mL over a 1-year period. Safety of injecting greater amounts on an annual basis has not been established."

Treatment Overview

Treatment with human and bovine collagen, according to the American Society of Plastic Surgeons, is usually a 30 to 60 minute procedure which involves injection of the product at several points along the edge of the treatment site. Following the injections, minor discomfort, stinging, throbbing, swelling, brusing, scabbing or redness is not uncommon, although these side effects usually subside within a few days. Lastly, because the body reabsorbs much of the saline found in Zyderm I, Zyderm II, CosmoDerm I, and CosmoDerm II, physicians usually overfill the treatment area by 150% to 200% when using these products. As a result, patients may notice significant swelling for 1 to 2 days following treatment.

Cost

Although the price of collagen injections may vary depending upon the size of the area being treated among other factors, according to the American Society for Aesthetic Plastic Surgery, the average cost of injections with Zyderm I, Zyderm II or Zyplast is $397 whereas the average cost of treatment with CosmoDerm I, CosmoDerm II or Cosmoplast is $490.