ZEEFEE LIQUID

Indications

• Insecticide for agricultural use
• Research tool in toxicology

Dosage

Children: Refer to the BNF for Children for specific dosing and administration guidelines.

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

Mechanism of action

Methyl parathion acts primarily by inhibiting the enzyme acetylcholinesterase, which is essential for the breakdown of the neurotransmitter acetylcholine. Its active metabolite, methyl paraoxon, is a potent inhibitor of both acetylcholinesterase and butyrylcholinesterase. The inhibition of these enzymes results in the accumulation of acetylcholine at synapses, leading to overstimulation of cholinergic receptors and resultant toxic effects.

Pharmacodynamics

The pharmacodynamics of methyl parathion involve its action as a noncompetitive inhibitor of acetylcholinesterase, causing prolonged effects of acetylcholine due to its inability to be hydrolyzed. The resultant cholinergic toxicity can lead to symptoms such as muscle twitching, respiratory distress, and potentially fatal outcomes if not treated promptly. The extent of inhibition is dose-dependent, with significant toxicity occurring after substantial enzyme inhibition.

Pharmacokinetics

Methyl parathion is absorbed through the gastrointestinal tract and can also be absorbed through the skin and respiratory tract. It is metabolized in the liver to form methyl paraoxon, which is responsible for the majority of its toxic effects. The distribution of methyl parathion in body tissues is influenced by its lipophilicity, and it is primarily excreted as metabolites in the urine. The elimination half-life and specific pharmacokinetic parameters can vary based on individual metabolism and exposure levels.

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether this drug is excreted in human milk. Caution is advised when administering to nursing women.

Storage

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

Formulations

• Liquid formulation

Indications

• Vitamin deficiency
• Nutritional supplementation
• Prevention of certain diseases
• Supporting metabolic functions

Dosage

Children: Refer to specific guidelines for individual vitamins or consult a healthcare professional for personalized dosing recommendations.

Adults: Refer to specific guidelines for individual vitamins or consult a healthcare professional for personalized dosing recommendations.

Mechanism of action

Vitamins function primarily as coenzymes or precursors for enzyme cofactors in various metabolic pathways. For instance, B vitamins are involved in energy metabolism by assisting in the conversion of carbohydrates, fats, and proteins into energy. Vitamin C acts as an antioxidant, protecting cells from damage, and is also crucial for collagen synthesis. Fat-soluble vitamins like A are involved in vision and immune function, while vitamin D regulates calcium and phosphate metabolism.

Pharmacodynamics

Vitamins exert their effects by participating in biochemical reactions and influencing metabolic pathways. For example, vitamin A is vital for vision and immune response, while vitamin D is important for maintaining bone health through its role in calcium absorption. The effects of vitamins can vary significantly depending on their solubility, with water-soluble vitamins typically being excreted more readily than fat-soluble ones, which can accumulate in the body.

Pharmacokinetics

The absorption of vitamins varies; water-soluble vitamins are generally absorbed in the small intestine and excreted in urine, while fat-soluble vitamins require dietary fats for absorption and are stored in the liver and fatty tissues. The bioavailability of vitamins can be affected by dietary composition, age, and health status. Elimination half-lives also differ; for instance, vitamin C has a shorter half-life compared to vitamin A, which can persist in the body for longer periods.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Constipation
• Headache
• Fatigue
• Allergic reactions

Interactions

• Fat-soluble vitamins (A, D, E, K) can accumulate and cause toxicity when taken in excess, especially with other supplements
• Certain medications (e.g., anticoagulants) may interact with vitamin K
• Vitamin C can enhance the absorption of iron supplements

Precautions

• Use caution in patients with kidney disease when taking vitamin D
• Monitor for signs of toxicity with high-dose vitamin supplementation
• Consider dietary sources of vitamins before recommending supplements

Pregnancy

Vitamins are generally considered safe during pregnancy when taken at recommended dosages. However, excessive intake, particularly of fat-soluble vitamins, should be avoided.

Breast-feeding

Most vitamins are safe during breastfeeding at recommended doses, but excessive amounts can affect breast milk composition.

Storage

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

Formulations

• Tablets
• Capsules
• Soft gels
• Powders
• Liquid solutions
• Chewable tablets

Mechanism of action

Acute poisoning ... is related to ... inhibiting action on enzyme acetylcholinesterase. Toxic manifestations generally occur only after more than 50% of plasma cholinesterase is inhibited. ... Methyl parathion ... depend on oxidative activation by replacement of thiono-sulfur with oxygen for ... toxicity. Methyl parathion has only a slight inhibitory action on acetylcholinesterase and butyrylcholinesterase, but its active metabolite, methyl paraoxon, is a potent inhibitor of both these enzymes. A study was conducted examining the inhibition of (Ca2+ and Mg2+)-ATPase by parathion (56382) and methyl parathion. Enzyme activity was assessed spectrophotometrically in pig erythrocyte membranes containing calcium2+ (Ca2+) and magnesium2+ and in solubilized membrane preparations incubated with the test agents. The enzyme response to ATP was biphasic. Equations expressing the kinetics of the substrate curves described two classes of the ATP binding active site, one with high affinity and low maximum rate and one with low affinity and high maximum rate. High affinity active sites were stimulated by low ATP concentrations (20 uM), whereas low affinity active sites were stimulated by high ATP levels (2 mM). Parathion and methylparathion dose dependently inhibited enzyme activity; parathion had a greater inhibitory effect than methylparathion. Lineweaver-Burke and Dixon plots indicated noncompetitive inhibition. Parathion and methylparathion induced enzyme inhibition occurred over a range of free calcium ion concentrations (0.5 to 5 mM); the inhibition was significantly greater at lower Ca2+ concentrations (1 to 100 uM) than at higher concentrations. The authors conclude that parathion and methylparathion inhibit ATPase activity by binding to a site on the enzyme rather than through an interaction with associated lipids. For more Mechanism of Action (Complete) data for METHYL PARATHION (6 total), please visit the HSDB record page.