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

GENERIC NAME: Recombinant Human Papillomavirus Quadrivalent Vaccine

BRAND NAME: Gardasil

DRUG CLASS AND MECHANISM: 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 HPV 6, 11, 16, and 18. The proteins in Gardasil are structural, virus-like proteins (VLP) that resemble the HPV virus. The proteins can activate the immune system, but cannot replicate. Viral proteins 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. In the event of HPV exposure following vaccination, 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. The FDA approved Gardasil in June 2007.

GENERIC AVAILABLE: No

PRESCRIPTION: Yes

PREPARATIONS: Injection: 0.5 ml single-dose vial

STORAGE: Store refrigerated at 2 to 8 C (36 to 46 F). Protect from light and do not freeze.

PRESCRIBED FOR: Gardasil is used for the prevention of HPV types 6, 11, 16, and 18 infections in girls and women 9 to 26 years of age. It is also approved for preventing genital warts caused by HPV types 6 and 11 in males 9 to 26 years old. 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 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.

DOSING: 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 third dose six months after the first dose.

DRUG INTERACTIONS: Gardasil may be administered concomitantly (at different sites) with hepatitis B vaccine. The use of immunosuppressive drugs reduces the efficacy of Gardasil. Hormonal contraceptives do not interact with Gardasil.

PREGNANCY: Gardasil is not recommended for use in pregnant women.

NURSING MOTHERS: It is not known whether Gardasil or the antibodies induced by Gardasil are excreted in breast milk.

SIDE EFFECTS: The most common side effects of Gardasil are fever, nausea, vomiting, fainting, dizziness, and mild or moderate pain, swelling, itching, and redness at the injection site. Patients should be observed for 15 minutes after injection because of fainting. Allergic reactions, which may be severe, also occur. Other side effects include swollen glands, Guillain-Barré syndrome, headache, joint pain, aching muscles, and tiredness or weakness. People allergic to any component in Gardasil should not use Gardasil.

Reference: Gardasil Prescribing Information