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Gardasil HPV Vaccine FAQ

Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

Gardasil (Recombinant Human Papillomavirus Quadrivalent Vaccine)

Gardasil is a human papillomavirus (HPV) vaccine synthesized using recombinant technology. Gardasil is a sterile preparation for intramuscular injection and contains purified, inactive proteins from four types of HPV virus. It is noninfectious and contains viral-like particles (VLP) from HPV types 6, 11, 16, and 18. Virus-like particles are structural virus proteins that resemble HPV virus. They can activate the immune system, but cannot replicate. Virus-like particles used in Gardasil are manufactured in yeast cells (S. cerevisiae) using recombinant technology. Once released from yeast cells, the VLPs are purified, combined with a catalyst (amorphous aluminum hydroxyphosphate sulfate) and a purification buffer.

Human papillomavirus causes cervical cancer, cervical adenocarcinoma, vaginal cancer and genital warts. Gardasil works by stimulating the immune system to attack HPV 6, 11, 16, and 18. Once Gardasil is administered, the body's immune system recognizes the viral proteins in Gardasil as foreign and develops antibodies against them, thus providing immunity to future infections. In the event of HPV exposure, the body will already be primed to fight the infection. HPV types 6, 11, 16, and 18 are commonly associated with HPV infections. HPV 16 and 18 cause 70% of cervical cancer and HPV 6, 11, 16 and 18 cause approximately 90% of genital warts.

In June 2006 the Food and Drug administration approved Gardasil for the prevention of HPV types 6, 11, 16, and 18 infections in girls and women aged 9-26 years. Gardasil protects against cervical cancer (cancer of the lower end of the uterus or womb); abnormal and precancerous cervical lesions; abnormal and precancerous vaginal lesions; abnormal and precancerous vulvar lesions and genital warts. Gardasil does not treat HPV associated diseases.

Effectiveness of Gardasil

Girls should receive Gardasil before they are sexually active. Gardasil 0.5 ml is injected intramuscularly in three separate doses. The first dose is administered at the patient's convenience, the second dose two months after the first dose, and the third dose six months after the first dose.

Gardasil was evaluated in 20,541 women 16-26 years of age prior to approval. Gardasil was effective in preventing 100% of cervical cancers and 99% of genital warts related to HPV 6, 11, 16, and 18. Gardasil does not protect against types of HPV not included in the vaccine and it does not treat HPV contracted prior to vaccination. Individuals who are already infected with one or more types of HPV included in Gardasil were protected from the remaining HPV types included in Gardasil following vaccination.

Precautions and Side Effects

The most common side effects of Gardasil are:

Patients should be observed for 15 minutes after injection because of fainting.

Allergic reactions, which may be severe, also occur.

Other side effects include:

People allergic to any component in Gardasil should not use Gardasil. Gardasil does not treat active genital warts or cervical cancer. Individuals with a compromised immune system will not respond as well to Gardasil as individuals with a normal immune system.

Last Editorial Review: 8/21/2008

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