Human Papillomavirus 9-Valent Vaccine, Recombinant

Usage

• Medical Conditions: Gardasil 9 is prescribed for the prevention of certain cancers and diseases caused by 9 types of HPV (Human Papillomavirus) in females and males. These include cervical, vulvar, vaginal, and anal cancers, as well as genital warts and certain head and neck cancers. It’s important to note that this vaccine is preventative, not curative, and does not treat existing HPV infections.
• Pharmacological Classification: Vaccine (viral vaccine, recombinant subunit vaccine).
• Mechanism of Action: Gardasil 9 stimulates the body’s immune system to produce antibodies against nine HPV types (6, 11, 16, 18, 31, 33, 45, 52, and 58). These antibodies help protect against future infection with these HPV types. The vaccine contains virus-like particles (VLPs) resembling the outer shell of HPV but lacking viral DNA, making it non-infectious and unable to cause HPV infection or cancer.

Alternate Names

• Generic Name: Human Papillomavirus 9-valent Vaccine, Recombinant
• Brand Name: Gardasil 9

How It Works

• Pharmacodynamics: Gardasil 9 triggers an immune response by mimicking a natural HPV infection, causing the body to produce type-specific antibodies against the nine HPV types. These antibodies neutralize HPV virions, preventing initial infection and subsequent development of HPV-related diseases.
• Pharmacokinetics: The vaccine is administered intramuscularly. The VLPs are taken up by antigen-presenting cells, leading to antibody production. The pharmacokinetic properties relating to absorption, distribution, metabolism, and excretion of the VLPs have not been specifically characterized.
• Mode of Action: The vaccine’s VLPs bind to and are taken up by antigen-presenting cells, leading to activation of B cells and the production of HPV-specific antibodies.
• Receptor Binding/Enzyme Inhibition: The mechanism primarily involves antibody-mediated neutralization of HPV, not direct receptor binding or enzyme inhibition.
• Elimination Pathways: The specific elimination pathways of the VLPs have not been fully elucidated.

Dosage

Standard Dosage

Adults (9 through 45 years of age):

• 0.5 mL intramuscularly.

Two-Dose Schedule:

• First dose: At elected date.
• Second dose: 6-12 months after the first dose.

Three-Dose Schedule:

• First dose: At elected date.
• Second dose: 1-2 months after the first dose.
• Third dose: 6 months after the first dose.

Children (9 through 14 years of age):

• 0.5 mL intramuscularly. Can follow either the two-dose or three-dose schedule as outlined above.

Special Cases:

• Elderly Patients (over 45 years): Not indicated.
• Patients with Renal Impairment: No dose adjustment is required.
• Patients with Hepatic Dysfunction: No dose adjustment is required.
• Patients with Comorbid Conditions: Use with caution in immunocompromised patients (e.g., HIV, cancer). They should receive the three-dose schedule.

Clinical Use Cases

Gardasil 9 is solely indicated for the prevention of HPV-related diseases and not for use in acute clinical situations like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.

Dosage Adjustments

No dose adjustment is generally needed except for immunocompromised individuals, who should receive the three-dose schedule.

Side Effects

Common Side Effects:

• Injection site reactions (pain, swelling, redness, itching, bruising, bleeding).
• Headache
• Fever
• Nausea
• Dizziness

Rare but Serious Side Effects:

• Allergic reactions (e.g., difficulty breathing, hives, swelling of the face and throat)
• Syncope (fainting) sometimes accompanied by tonic-clonic movements

Long-Term Effects: Currently, no long-term adverse effects have been identified.

Adverse Drug Reactions (ADR):

• Severe allergic reaction (anaphylaxis)

Contraindications

• Hypersensitivity to any component of the vaccine, including yeast.
• History of anaphylaxis following a previous dose of Gardasil 9 or Gardasil.

Drug Interactions

• Immunosuppressants: May reduce the immune response to the vaccine.
• Other Vaccines: Can be co-administered with other vaccines (e.g., dTap, dT-IPV, Menactra, Adacel) at separate injection sites.
• Hormonal Contraceptives: Do not affect the efficacy of Gardasil 9.

Pregnancy and Breastfeeding

• Pregnancy: Data are limited. While no adverse effects have been observed in post-marketing surveillance, it is generally recommended to postpone vaccination until after pregnancy.
• Breastfeeding: Data are limited. No adverse effects on breastfed infants have been reported. Vaccination is not considered a contraindication to breastfeeding.

Drug Profile Summary

• Mechanism of Action: Stimulates production of antibodies against 9 HPV types.
• Side Effects: Injection site reactions, headache, fever, nausea, dizziness; rarely, allergic reactions or syncope.
• Contraindications: Hypersensitivity to vaccine components, history of anaphylaxis after Gardasil 9 or Gardasil.
• Drug Interactions: Immunosuppressants may reduce effectiveness, can be co-administered with other vaccines.
• Pregnancy & Breastfeeding: Limited data; generally recommended to postpone during pregnancy; no contraindication to breastfeeding.
• Dosage: Adults/Children (9-45 years): 0.5 mL IM; 2- or 3-dose schedule based on age at initial vaccination.
• Monitoring Parameters: Observe for allergic reactions and syncope after administration.

Popular Combinations

Gardasil 9 can be safely co-administered with other vaccines like dTap, dT-IPV, Menactra, and Adacel, but at separate injection sites.

Precautions

• General Precautions: Screen for allergies, especially to yeast and prior HPV vaccinations. Observe patient for 15 minutes post-vaccination for syncope.
• Specific Populations: Pregnant women: Postpone unless benefits outweigh risks. Breastfeeding mothers: No known contraindication. Children & Elderly: Approved for ages 9 through 45; not studied in children under 9 or adults over 45.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Human Papillomavirus 9-Valent Vaccine, Recombinant?

A: 0.5 mL intramuscularly. Two-dose schedule (0, 6-12 months) for ages 9-14 at initial vaccination. Three-dose schedule (0, 1-2, 6 months) for ages 15 and older at initial vaccination.

Q2: Can Gardasil 9 cure an existing HPV infection?

A: No. Gardasil 9 is a preventative vaccine, not a treatment for existing HPV infections.

Q3: Who should receive Gardasil 9?

A: Recommended for all individuals ages 9 through 45 years, regardless of gender.

Q4: What are the most common side effects?

A: Pain, swelling, redness, and itching at the injection site, headache, fever, nausea, and dizziness.

Q5: Can Gardasil 9 be given during pregnancy?

A: Data are limited. It’s generally recommended to postpone vaccination until after pregnancy.

Q6: Does Gardasil 9 protect against all types of HPV?

A: No, Gardasil 9 protects against 9 HPV types (6, 11, 16, 18, 31, 33, 45, 52, 58), which are associated with the highest risk of HPV-related cancers and genital warts. It does not protect against all HPV types.

Q7: How long does the protection from Gardasil 9 last?

A: Long-term studies are ongoing. Current data suggests long-lasting protection, but the need for a booster dose in the future is still being evaluated.

Q8: What should I do if my patient faints after receiving the vaccine?

A: Observe the patient for 15 minutes post-vaccination. If fainting occurs, ensure they are in a safe position and monitor their vital signs until they recover.

Q9: Can Gardasil 9 be given to immunocompromised individuals?

A: Yes, they should receive the three-dose schedule. The immune response may be less robust than in immunocompetent individuals.

Q10: Are there any drug interactions I should be aware of?

A: Immunosuppressants can potentially reduce the efficacy of Gardasil 9. It can be safely co-administered with other vaccines at separate injection sites.