Fowl Pox Vaccine

Indications

• Schistosomiasis
• Infections caused by Clonorchis sinensis
• Infections caused by Opisthorchis viverrini

Dosage

Children: Refer to BNF for Children for specific dosing guidance.

Adults: Refer to BNF for specific dosing guidance.

Mechanism of action

Although the exact mechanism of action is unknown, praziquantel is hypothesized to target the β subunits of voltage-gated Ca2+ channels, particularly in Schistosoma mansoni and Schistosoma japonicum. Co-administration of calcium channel blockers such as nicarpidine and nifedipine can render some Schistosoma mansoni resistant to praziquantel, suggesting that the drug's action is related to alterations in calcium permeability.

Pharmacodynamics

In vitro studies have shown that praziquantel induces rapid contraction of schistosomas through a specific effect on cell membrane permeability. This leads to vacuolization and disintegration of the schistosome tegument. The drug's action is more pronounced in adult worms compared to juveniles, with increased Ca2+ influx being a significant factor. Secondary effects include inhibition of glucose uptake, reduced glycogen levels, and increased lactate release. Praziquantel is selectively effective against trematodes and cestodes, with little effect on nematodes.

Pharmacokinetics

Praziquantel is rapidly absorbed after oral administration, with peak plasma concentrations typically occurring within 1 to 2 hours. It is extensively metabolized in the liver, and its metabolites are excreted primarily in urine. The drug has a half-life of approximately 1 to 2 hours, necessitating single-dose administration for many indications. The pharmacokinetic profile supports its use as an effective treatment for acute infections.

Adverse effects

• Headache
• Dizziness
• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Rash
• Fatigue

Interactions

• Calcium channel blockers (e.g. nicarpidine, nifedipine) may reduce the efficacy of praziquantel

Precautions

• Use with caution in patients with hepatic impairment
• Monitor for adverse effects in patients with a history of seizures

Pregnancy

Praziquantel should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as there is limited data on its safety.

Breast-feeding

Praziquantel is excreted in breast milk; caution should be exercised when administered to nursing mothers.

Storage

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

Formulations

• Tablets
• Oral suspension

Indications

• Clinical term 1
• Common term 1
• Clinical term 2
• Common term 2

Dosage

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

Adults: Refer to the BNF for specific adult dosing guidelines.

Mechanism of action

Dose acts by modulating the activity of specific neurotransmitter receptors and ion channels, influencing various physiological pathways. Its precise mechanism may involve interactions with G-protein coupled receptors, leading to downstream signaling effects that impact cellular responses.

Pharmacodynamics

Dose exhibits a range of effects depending on the dosage and target tissues. It is known to alter neurotransmitter release, affect ion conductance, and influence metabolic pathways, thereby contributing to its therapeutic efficacy and potential side effects.

Pharmacokinetics

Dose is generally absorbed following administration, with peak plasma concentrations occurring within a specified timeframe. Its distribution is influenced by tissue binding and permeability across cell membranes. The drug is metabolized primarily in the liver, with metabolites being excreted via renal and biliary routes. The half-life can vary based on individual patient factors, including age, liver function, and other concurrent medications.

Dosage

Children: Refer to specific guidelines based on the type of fowl and intended use, as dosing is highly variable and specific to the context.

Adults: Refer to specific guidelines based on the type of fowl and intended use, as dosing is highly variable and specific to the context.

Pregnancy

Not applicable.

Breast-feeding

Not applicable.

Storage

Store in a cool, dry place away from direct sunlight.

Indications

• Bacterial infections
• Viral infections
• Epidemiological studies
• Antibiotic resistance monitoring

Dosage

Children: Refer to specific antimicrobial treatment guidelines based on the strain identified and the infection site.

Adults: Refer to specific antimicrobial treatment guidelines based on the strain identified and the infection site.

Mechanism of action

The mechanism of action for a strain depends on the type of microorganism it represents. For pathogenic bacteria, the strain may produce toxins, evade the host's immune response, or possess resistance mechanisms that allow it to survive in the presence of antibiotics. For viruses, strains may exhibit mutations that alter their ability to infect host cells or evade antiviral therapies.

Pharmacodynamics

Pharmacodynamics in the context of strains involves the interaction between the strain and the host's immune system, as well as the effects of specific antimicrobial agents on the strain. These interactions can influence the efficacy of treatments and the development of resistance.

Pharmacokinetics

Pharmacokinetics is not directly applicable to strains themselves but rather to the drugs used to treat infections caused by specific strains. Factors such as absorption, distribution, metabolism, and excretion of antimicrobial agents can vary depending on the strain's characteristics and the site of infection.

Pregnancy

There is limited information on the safety of strain in pregnancy. It is advisable to consult healthcare professionals for guidance.

Breast-feeding

Safety during breastfeeding is not well established. It is recommended to seek medical advice before use.

Storage

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

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.

Mechanism of action

Although the exact mechanism of action is unknown, praziquantel was hypothesized to target the β subunits of voltage-gated Ca₂₊ channels, particularly in Schistosoma mansoni and Schistosoma japonicum, due to the lack of two conserved serine residues in these subunits. This is supported by the finding that co-administration of calcium channel blockers like nicarpidine and nifedipine renders 50% of Schistosoma mansoni resistant to praziquantel. Increased exposure of antigens on the worm surface was also observed, but little research has been done to elucidate on the mechanism of action.

Pharmacodynamics

In vitro studies on trematodes and cestodes have shown that praziquantel induces a rapid contraction of schistosomas by a specific effect on the permeability of the cell membrane. The drug further causes vacuolization and disintegration of the schistosome tegument. The effect is more marked on adult worms compared to young worms. An increased Ca2⁺-influx may play an important role. Secondary effects are inhibition of glucose uptake, lowering of glycogen levels and stimulation of lactate release. The action of praziquantel is specific to trematodes and cestodes; nematodes (including filariae) are not affected. Praziquantel is active against schistosoma (for example, Schistosoma mekongi, Schistosoma japonicum, Schistosoma mansoni and Schistosoma hematobium), and infections due to the liver flukes, Clonorchis sinensis/Opisthorchis viverrini. Published in vitro data have shown a potential lack of efficacy of praziquantel against migrating schistosomulae. An interesting quirk of praziquantel is that it is relatively ineffective against juvenile schistosomes. While initially effective, effectiveness against schistosomes decreases until it reaches a minimum at 3-4 weeks. Effectiveness then increases again until it is once again fully effective at 6-7 weeks.