PREVENAR 13

Indications

• Prevention of pneumococcal pneumonia
• Prevention of pneumococcal meningitis
• Prevention of pneumococcal bacteremia
• Prevention of otitis media caused by Streptococcus pneumoniae

Dosage

Children: Refer to the BNF for Children for specific vaccination schedules and dosages for children.

Adults: Refer to specific guidelines for pneumococcal vaccination in adults, typically involving one or more doses depending on health status and risk factors.

Mechanism of action

Pneumococcal vaccines work by inducing an immune response against polysaccharides found on the capsule of Streptococcus pneumoniae. The conjugate vaccines link these polysaccharides to a protein carrier, enhancing the immunogenicity, particularly in young children. Upon vaccination, the immune system produces antibodies against the polysaccharides, providing protection against future infections by preventing bacterial adherence and promoting opsonization.

Pharmacodynamics

The pneumococcal vaccines stimulate both humoral and cellular immune responses. The primary outcome is the production of specific antibodies that can neutralize the bacteria and mediate opsonophagocytosis. The effectiveness of the vaccines can depend on factors such as the patient's age, immune status, and the specific serotypes included in the vaccine formulation. The duration of immunity varies, with periodic booster doses recommended in some populations.

Pharmacokinetics

As pneumococcal vaccines are administered intramuscularly, they are absorbed into the systemic circulation. The pharmacokinetics of the vaccine components are not typically characterized in the same way as small molecules, as the immunogenic response is the primary outcome of interest. The onset of immunity generally occurs within 2 to 3 weeks after vaccination, with peak antibody levels reached in several weeks. The metabolism and excretion of vaccine components are related to the immune system's response rather than classical pharmacokinetic pathways.

Adverse effects

• Injection site reactions (pain, swelling, redness)
• Fever
• Fatigue
• Headache
• Muscle pain
• Joint pain

Precautions

• Use with caution in individuals with a history of severe allergic reactions.
• Monitor for allergic reactions after administration.
• Consider immunosuppressed patients may have a reduced immune response.

Pregnancy

The safety of pneumococcal vaccines during pregnancy is not fully established. Vaccination may be considered if the benefits outweigh the risks, especially in high-risk populations.

Breast-feeding

Pneumococcal vaccines are generally considered safe during breastfeeding, as they are not transmitted in breast milk.

Storage

Store in a refrigerator at 2°C to 8°C. Do not freeze. Protect from light.

Formulations

• Pneumococcal polysaccharide vaccine (PPSV23)
• Pneumococcal conjugate vaccine (PCV13)

Mechanism of action

Polysaccharides exert their effects through various mechanisms, often involving the modulation of immune responses. For example, certain polysaccharides can act as pathogen-associated molecular patterns (PAMPs) that are recognized by pattern recognition receptors on immune cells, leading to the activation of innate immunity. Additionally, some polysaccharides can enhance the proliferation and activation of lymphocytes, such as T-cells and B-cells, thereby influencing adaptive immune responses. Some polysaccharides also play a role in anticoagulation by inhibiting thrombin and other factors in the coagulation cascade.

Pharmacodynamics

The pharmacodynamics of polysaccharides vary widely depending on their structure and the specific biological pathways they influence. For instance, polysaccharides that act as immunomodulators can increase cytokine production, enhance phagocytosis by macrophages, and promote the differentiation of immune cells, leading to a more robust immune response. Furthermore, polysaccharides can exhibit anti-inflammatory properties by modulating the release of pro-inflammatory cytokines and chemokines. In the case of anticoagulant polysaccharides, their action may involve the binding and inhibition of specific clotting factors, thus preventing thrombus formation.

Pharmacokinetics

The pharmacokinetics of polysaccharides depend on their molecular weight, structure, and route of administration. Generally, polysaccharides are poorly absorbed in the gastrointestinal tract when taken orally due to their large size and complexity. However, certain polysaccharides are designed for parenteral administration, where they can be directly introduced into the bloodstream. Following administration, they may be metabolized by specific enzymes or by gut microbiota. The elimination half-life can vary significantly, influenced by factors such as the degree of sulfation or acetylation, which can affect their

Pregnancy

Polysaccharides are generally considered safe during pregnancy, but specific formulations should be evaluated on a case-by-case basis. Always consult a healthcare provider.

Breast-feeding

Polysaccharides are typically considered safe during breastfeeding, although individual formulations may vary. Consultation with a healthcare provider is recommended.

Storage

Polysaccharides should be stored in a cool, dry place, away from direct sunlight and moisture. Specific storage conditions may vary depending on the formulation.