CYVAC

Indications

• Acute uncomplicated malaria
• Severe malaria
• Malaria prophylaxis
• Relapse prevention in vivax malaria

Dosage

Children: Refer to BNF for Children for paediatric dosing, as it is determined by age and weight.

Adults: Refer to specific BNF text for adult dosing as it varies by drug and indication.

Mechanism of action

Antimalarial drugs act through various mechanisms depending on the specific medication. For example, chloroquine inhibits the heme polymerase enzyme, preventing the detoxification of heme, which accumulates to toxic levels in the malaria parasite. Quinine interferes with the parasite's ability to metabolize glucose, affecting energy production. Artemisinin derivatives produce reactive oxygen species and alkylate proteins, leading to parasite death.

Pharmacodynamics

Antimalarials exhibit a range of pharmacodynamic properties, including rapid onset of action, with some like artemisinin providing quick relief from symptoms. The efficacy of treatment can vary depending on the drug used, the species of Plasmodium, and the presence of drug-resistant strains. The goal of treatment is to eliminate the parasite, prevent relapse, and reduce transmission.

Pharmacokinetics

Pharmacokinetics of antimalarial drugs varies widely. For example, chloroquine has a long half-life, allowing for once-daily dosing, while artemisinin has a short half-life, necessitating combination therapy for sustained efficacy. Absorption rates can be affected by food intake, and distribution is typically extensive with high protein binding. Metabolism primarily occurs in the liver, and excretion is mainly through urine.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Headache
• Dizziness
• Rash
• Visual disturbances
• Hearing loss
• Severe allergic reactions

Interactions

• Antacids may reduce absorption of certain antimalarials
• Drug metabolism may be altered by concomitant use of other medications, such as certain anticonvulsants or antibiotics

Precautions

• Use cautiously in patients with hepatic or renal impairment
• Monitor for signs of hematological reactions in patients receiving long-term therapy
• Consider potential resistance in endemic areas

Pregnancy

Some antimalarials are contraindicated in pregnancy, while others are considered safe. Consult local guidelines for specific medications.

Breast-feeding

Many antimalarials are excreted in breast milk, but some are considered safe for use during breastfeeding. Consult local guidelines for specific medications.

Storage

Store at room temperature, away from moisture and heat. Check specific product labeling for detailed storage instructions.

Formulations

• Oral tablets
• Intravenous formulations
• Suspensions
• Combination therapies

Indications

• Prevention of infectious diseases such as measles, mumps, rubella, hepatitis B, influenza, and human papillomavirus (HPV)
• Travel vaccinations for diseases endemic to certain regions
• Vaccination for at-risk populations, such as those with compromised immune systems or specific occupational exposures

Dosage

Children: Dosage varies by vaccine type and age; refer to the BNF for Children for specific dosing information.

Adults: Dosage varies by vaccine type and indication; refer to specific guidelines for each vaccine.

Mechanism of action

Vaccines work by mimicking an infection. They introduce a harmless component of a pathogen (antigen) to the immune system, prompting the body to produce an immune response. This includes the generation of antibodies and memory cells that provide long-term immunity. Upon subsequent exposure to the actual pathogen, the immune system is primed to respond more rapidly and effectively.

Pharmacodynamics

The pharmacodynamics of vaccines involves the activation of both humoral and cellular immunity. Vaccines stimulate B cells to produce antibodies against the pathogen, while T cells are activated to destroy infected cells. This dual response helps to establish immunological memory, which enables a faster and more robust response upon re-exposure to the pathogen.

Pharmacokinetics

Vaccines are administered via various routes, including intramuscular, subcutaneous, and oral. After administration, the antigens are presented to antigen-presenting cells, which activate T cells and stimulate B cell proliferation and differentiation. The half-life of vaccine-induced immunity varies depending on the type of vaccine, with some providing lifelong immunity and others requiring booster doses to maintain protection.

Contra-indications

• Severe allergic reaction (anaphylaxis) to a component of the vaccine
• Severe immunocompromised state for live attenuated vaccines

Adverse effects

• Local reactions at the injection site (pain, redness, swelling)
• Fever
• Fatigue
• Headache
• Muscle pain
• Joint pain
• Nausea

Interactions

• Immunosuppressive medications may reduce vaccine efficacy
• Concurrent administration of some vaccines may require spacing to optimize immune response

Precautions

• History of allergic reactions to vaccines or vaccine components
• Pregnancy (specific vaccines may be contraindicated)
• Moderate to severe acute illness with or without fever

Pregnancy

Consult healthcare provider. Some vaccines are contraindicated during pregnancy, while others are recommended.

Breast-feeding

Generally considered safe, but consult healthcare provider regarding specific vaccines.

Storage

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

Formulations

• Liquid suspension for injection
• Lyophilized powder for reconstitution