SHINGRIX

Indications

• Vaccination against infectious diseases
• Allergy testing and immunotherapy
• Monoclonal antibody production
• Transplantation to prevent organ rejection

Dosage

Children: Dosing of antigens in children also depends on the specific antigen and the clinical indication. For pediatric vaccinations, refer to the BNF for Children.

Adults: Dosing of antigens is highly variable and depends on the specific antigen and the clinical indication. For vaccine administration, refer to national immunization guidelines.

Mechanism of action

Antigens work by binding to specific receptors on the surface of immune cells, such as B cells and T cells. This binding triggers a cascade of immune responses, including the proliferation of specific immune cell populations and the production of antibodies that target the antigen. This process is crucial for the development of adaptive immunity, allowing the body to remember and respond more effectively to future encounters with the same antigen.

Pharmacodynamics

The pharmacodynamics of antigens involve the interaction with the immune system to elicit a response. The magnitude and quality of this response can vary based on several factors, including the nature of the antigen, the route of exposure, and the host's immune status. Antigens can be classified as T-cell dependent or T-cell independent, influencing the type of immune response generated.

Pharmacokinetics

Antigens are processed by antigen-presenting cells (APCs) that present peptide fragments to T cells. The pharmacokinetics of antigens can vary widely depending on their form (e.g., live attenuated, inactivated, or subunit vaccines). Generally, once introduced into the body, antigens are taken up by APCs, which then migrate to lymph nodes to activate T and B cells. The duration of immune response can be influenced by the type of antigen and the presence of adjuvants.

Pregnancy

Safety during pregnancy depends on the specific type of antigen. Consult relevant guidelines for specific antigens.

Breast-feeding

Safety during breastfeeding varies by antigen type. Consult relevant guidelines for specific antigens.

Storage

Store at controlled room temperature, away from light and moisture. Specific storage conditions may vary based on the type of antigen.

Mechanism of action

Glycoproteins exert their effects primarily through their carbohydrate moieties, which can interact with specific receptors on cell surfaces. This interaction can initiate signaling pathways that lead to various cellular responses, including changes in gene expression, enzyme activity, and cell proliferation. The specific mechanisms may vary depending on the type of glycoprotein and its biological context.

Pharmacodynamics

The pharmacodynamics of glycoproteins involve their ability to bind to specific receptors, leading to downstream effects that can modulate physiological processes. These interactions can influence immune responses, hormonal signaling, and cellular communication. The functional outcomes depend on the specific glycoprotein and the tissues involved.

Pharmacokinetics

The pharmacokinetics of glycoproteins can vary significantly based on their structure and the presence of carbohydrate chains. Generally, glycoproteins are subject to modification by glycosylation, which can affect their stability, distribution, and elimination in the body. They may be metabolized by proteolytic enzymes and can have varying half-lives depending on their molecular size and composition.

Pregnancy

The safety of glycoprotein during pregnancy has not been well established. Consult relevant guidelines and clinical resources.

Breast-feeding

The effects of glycoprotein on breastfeeding have not been well studied. Caution is advised.

Storage

Store in a cool, dry place, away from direct sunlight. Keep out of reach of children.

Indications

• Prevention of varicella (chickenpox) in children and adults
• Post-exposure prophylaxis in individuals at high risk of severe disease

Dosage

Children: Refer to specific guidelines for varicella vaccination and management in children.

Adults: Refer to specific guidelines for varicella vaccination and management in adults.

Mechanism of action

The varicella-zoster virus enters the body through the respiratory tract and mucosal tissues. It replicates in lymphoid tissues and then disseminates through the bloodstream, leading to a systemic infection. The virus causes the characteristic skin lesions by infecting epidermal cells, leading to cell lysis and the formation of vesicular lesions. The immune response to the infection ultimately leads to the resolution of the disease and the formation of latent virus in sensory nerve ganglia.

Pharmacodynamics

The pharmacodynamics of varicella involves the immune response elicited by the body upon infection. The primary response includes the production of antibodies specific to VZV, which help to neutralize the virus and prevent further infection. Additionally, T-cell mediated immunity plays a crucial role in controlling the infection and preventing reactivation of the virus later in life, which can result in herpes zoster (shingles).

Pharmacokinetics

Varicella-zoster virus has a complex pharmacokinetic profile. After initial infection, the virus undergoes replication in lymphoid tissue, followed by viremia and subsequent infection of the skin. The onset of the rash typically occurs 10 to 21 days after exposure. The virus can remain dormant in sensory ganglia and may reactivate later in life, causing herpes zoster. The vaccine, when administered, stimulates an immune response without causing the disease, leading to the establishment of immunity.

Contra-indications

• Hypersensitivity to varicella vaccine components
• Immunocompromised individuals
• Pregnant women

Adverse effects

• Injection site reactions (pain, redness, swelling)
• Mild rash
• Fever
• Fatigue
• Headache

Interactions

• Corticosteroids may reduce vaccine effectiveness
• Immunosuppressive therapies may alter immune response to vaccination

Precautions

• Assess for history of allergic reactions to previous vaccines
• Monitor for potential interactions with immunosuppressive medications
• Consider the risk of transmission to susceptible individuals

Pregnancy

Varicella vaccine is contraindicated during pregnancy due to potential risks to the fetus.

Breast-feeding

Breastfeeding is not a contraindication for varicella vaccination; however, consult healthcare provider for individual cases.

Storage

Store at 2-8 degrees Celsius. Do not freeze. Protect from light.

Formulations

• Live attenuated varicella vaccine, administered subcutaneously

Indications

• Influenza
• HIV/AIDS
• Hepatitis B and C
• Herpes simplex virus infections
• Cytomegalovirus infections
• COVID-19
• Respiratory syncytial virus infections

Dosage

Children: Refer to specific antiviral agents for dosing guidance.

Adults: Refer to specific antiviral agents for dosing guidance.

Mechanism of action

Viruses infect host cells by attaching to specific receptors on the cell surface. Once inside, they hijack the host cell's machinery to replicate their genetic material and produce viral proteins. New viral particles are assembled and released from the host cell, often destroying the cell in the process. The specific mechanism can vary depending on the virus type, including integration into the host genome in retroviruses or utilizing specific pathways for replication.

Pharmacodynamics

The pharmacodynamics of antiviral agents depend on the specific virus and the mechanism of action. Antiviral drugs may inhibit viral entry into host cells, block viral replication, or prevent the assembly of new virions. The effectiveness of antiviral therapy often relates to the stage of viral replication and the immune response of the host.

Pharmacokinetics

Pharmacokinetics of antiviral drugs varies widely based on the specific medication used. Generally, antiviral agents are absorbed through the gastrointestinal tract and distributed throughout the body. They may undergo hepatic metabolism and are often excreted through the kidneys. The half-life of these drugs can range from a few hours to several days, influencing dosing schedules.

Indications

• Zoster (shingles)
• Postherpetic neuralgia

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing information.

Adults: Refer to clinical guidelines and the BNF for specific dosing recommendations.

Mechanism of action

The varicella-zoster virus (VZV) primarily affects neurons and skin cells. Upon reactivation, the virus travels down sensory nerves to the skin, where it causes inflammation and vesicular lesions. Antiviral medications can inhibit viral replication and reduce the severity and duration of symptoms by targeting the viral DNA polymerase, disrupting the viral life cycle.

Pharmacodynamics

Antiviral agents used in the treatment of zoster, such as acyclovir, valacyclovir, and famciclovir, exhibit activity against VZV by inhibiting viral DNA synthesis. These drugs are phosphorylated by viral thymidine kinase, leading to the formation of a triphosphate that competes with deoxyguanosine triphosphate, ultimately resulting in the termination of viral DNA chain elongation.

Pharmacokinetics

Acyclovir, for example, is absorbed following oral administration, with peak plasma concentrations typically reached within 1-2 hours. The bioavailability is approximately 15-30%. It is widely distributed throughout body tissues and fluids, including the central nervous system, and is primarily eliminated by the kidneys via glomerular filtration and tubular secretion. The half-life of acyclovir is about 2.5 to 3 hours in individuals with normal renal function.

Adverse effects

• Injection site reactions
• Fever
• Fatigue
• Headache
• Myalgia
• Nausea

Precautions

• Use with caution in immunocompromised patients
• Monitor for potential allergic reactions

Pregnancy

Zoster vaccines are generally not recommended during pregnancy due to insufficient data on safety.

Breast-feeding

It is not known whether zoster vaccine is excreted in human milk. Caution is advised.

Storage

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

Formulations

• Live attenuated zoster vaccine