PODIVIL

Indications

• Skin disinfection
• Ocular antisepsis before surgery
• Treatment of conjunctivitis
• Prevention of infection in minor wounds

Dosage

Children: Refer to product literature for specific dosing recommendations for children, as doses may vary based on the formulation used.

Adults: For ocular antisepsis, apply povidone-iodine solution to the eye area, leave for 2 minutes, then irrigate thoroughly with sodium chloride 0.9%. For skin disinfection, consult product literature for specific dosing instructions.

Mechanism of action

Povidone-iodine releases free iodine, which penetrates microbial cell walls, leading to the disruption of protein synthesis and cellular metabolism. This mechanism results in the bactericidal and virucidal activity of the compound, effectively reducing microbial load on skin and mucous membranes.

Pharmacodynamics

The antiseptic properties of povidone-iodine arise from its ability to disrupt cellular protein synthesis in microorganisms. The solution is effective at low concentrations, and its broad-spectrum activity includes efficacy against both gram-positive and gram-negative bacteria, as well as viruses and fungi. The rapid action of povidone-iodine makes it suitable for preoperative disinfection and wound care.

Pharmacokinetics

Povidone-iodine is primarily used topically, and systemic absorption is minimal when applied to intact skin. When used in ocular applications, the solution can be absorbed across the conjunctival membrane, although the extent of systemic absorption is low. The elimination of iodine from the body primarily occurs via renal pathways, and the half-life can vary based on the route of administration.

Contra-indications

• Hypersensitivity to povidone-iodine or any of its components
• Concomitant use of ocular formulations containing mercury-based preservatives
• Use in preterm neonates

Adverse effects

• Eye erythema
• Punctate keratitis
• Eye irritation (upon prolonged administration)
• Eye pain
• Headache
• Hypotension
• Common or very common side effects include eye stinging, nausea, syncope, and blurred vision

Interactions

• Potential interaction with ganciclovir when used in eye procedures

Precautions

• Caution in patients with hypersensitivity to aciclovir, valaciclovir, or famciclovir
• Avoid regular or excessive use during breastfeeding

Pregnancy

Manufacturer advises caution due to potential teratogenic effects observed in animal studies; effective contraception is recommended during treatment.

Breast-feeding

Manufacturer advises avoiding use unless no suitable alternative is available; limited information on safety.

Storage

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

Formulations

• Povidone-iodine 5% eye drops
• Povidone-iodine skin cleanser
• Povidone-iodine antiseptic solution

Dosage

Children: Refer to the BNF for Children for appropriate dosing information in paediatric cases, especially in instances of overdose.

Adults: Refer to the BNF for specific dosing information based on clinical circumstances, particularly in cases of overdose.

Mechanism of action

Ethylene glycol is metabolized by alcohol dehydrogenase to glycoaldehyde, which is subsequently converted to glycolic, glyoxylic, and oxalic acids. These metabolites contribute to anion gap metabolic acidosis and are responsible for tissue injury through the formation of insoluble calcium oxalate crystals.

Pharmacodynamics

The toxicity of ethylene glycol arises from its metabolites, particularly glycolic and oxalic acids. These compounds induce metabolic acidosis, lead to renal failure through calcium oxalate crystal deposition in the kidneys, and can cause neurological impairment. The anion gap increases due to the accumulation of these acids, leading to complications such as cardiovascular instability and potential multi-organ failure.

Pharmacokinetics

Ethylene glycol is rapidly absorbed after oral ingestion. It undergoes first-pass metabolism primarily in the liver, where it is converted into its toxic metabolites. The elimination half-life of ethylene glycol varies but is generally prolonged in cases of renal impairment. Renal excretion of metabolites contributes to the duration of toxicity, necessitating prompt medical intervention in cases of overdose.

Adverse effects

• Metabolic acidosis
• Renal failure
• CNS depression
• Hypocalcemia
• Cardiovascular collapse
• Pulmonary edema

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of metabolic acidosis
• Evaluate electrolyte levels, particularly calcium

Pregnancy

There is limited data on the safety of ethylene glycol in pregnancy. It should only be used if clearly needed.

Breast-feeding

It is unknown if ethylene glycol is excreted in human milk. Caution is advised.

Storage

Store in a tightly closed container at room temperature, away from heat and moisture.

Formulations

• Liquid

Dosage

Children: Refer to specific guidelines for pediatric dosing; consult the BNF for Children for accurate dosage information.

Adults: Refer to specific guidelines for use; dosage may vary based on the context of use.

Mechanism of action

Hydroxide ions act primarily as bases, neutralizing acids to form water and salts. They participate in various biochemical pathways, including selenium metabolism and the degradation of reactive oxygen species. Hydroxide can influence enzyme activity and stability by altering the pH of the environment, thereby affecting metabolic reactions.

Pharmacodynamics

Hydroxide ions can impact biological processes by changing the local pH, which influences enzyme activity, ion transport, and the solubility of other compounds. Their ability to neutralize acids can help regulate physiological pH, contributing to homeostasis in living organisms.

Pharmacokinetics

As an inorganic ion, hydroxide does not undergo traditional pharmacokinetic processes like absorption, distribution, metabolism, or excretion. Instead, it is rapidly equilibrated in biological fluids and participates in acid-base reactions, having immediate effects on the local environment.

Pregnancy

There is limited information regarding the use of hydroxide during pregnancy. Consult a healthcare professional for advice.

Breast-feeding

Limited data is available on the excretion of hydroxide in breast milk. Consult a healthcare professional before use.

Storage

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

Indications

• Iodine deficiency
• Hypothyroidism
• Goiter
• Thyroiditis

Dosage

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

Adults: Refer to the BNF for specific dosing information.

Mechanism of action

Iodide functions as a substrate for the synthesis of thyroid hormones. It undergoes metabolism through various pathways, including thyroid hormone metabolism via conjugation and degradation, deiodination, and biosynthesis. In the thyroid gland, iodide is actively transported into cells where it is oxidized to iodine, which then combines with the amino acid tyrosine to form T3 and T4, essential hormones for metabolic regulation.

Pharmacodynamics

Iodide is crucial for maintaining thyroid hormone levels in the body. Adequate iodide levels are necessary to prevent hypothyroidism and associated conditions such as goiter. The pharmacodynamic effects include modulation of metabolic processes, enhancement of growth and development, and regulation of energy expenditure. Insufficient iodide can lead to decreased thyroid hormone production and subsequent metabolic disturbances.

Pharmacokinetics

Iodide is absorbed from the gastrointestinal tract and is distributed throughout the body, particularly accumulating in the thyroid gland. The half-life of iodide in the serum is approximately 10-20 days, depending on dietary intake and physiological status. It is excreted primarily through the kidneys. The bioavailability of iodide can be influenced by various factors, including the presence of certain food components and the overall dietary iodide intake.

Pregnancy

Iodide is generally considered safe during pregnancy when used in appropriate doses, as it is essential for fetal thyroid function.

Breast-feeding

Iodide is excreted in breast milk, but it is usually safe in normal dietary amounts.

Storage

Store in a cool, dry place, protected from light.

Indications

• Emulsifying agent in drug formulations
• Stabilizer for parenteral preparations
• Solubilizer for hydrophobic drug compounds
• Ingredient in topical formulations

Dosage

Children: Refer to specific product guidelines, as dosing varies based on formulation and intended use.

Adults: Refer to specific product guidelines, as dosing varies based on formulation and intended use.

Mechanism of action

Polysorbate functions primarily as an emulsifying agent. It reduces the surface tension between immiscible liquids, allowing them to mix more easily. This property is particularly useful in stabilizing emulsions and suspensions, facilitating the delivery of active pharmaceutical ingredients in various formulations.

Pharmacodynamics

Polysorbate does not exert pharmacological effects in the traditional sense, as it does not bind to specific receptors to elicit a physiological response. Instead, it plays a crucial role in modifying the physical properties of drug formulations, thereby enhancing drug delivery and absorption. Its ability to solubilize drugs enhances their bioavailability, particularly for poorly soluble compounds.

Pharmacokinetics

Polysorbate is generally considered to be non-toxic and is not absorbed to a significant extent when administered orally. It is metabolized by the liver and excreted primarily through the gastrointestinal tract. The pharmacokinetic profile may vary depending on the route of administration and the specific formulation in which it is used.

Adverse effects

• Allergic reactions
• Skin irritation
• Gastrointestinal disturbances

Precautions

• Use cautiously in patients with known allergies to polysorbates or related compounds
• Monitor for allergic reactions in susceptible individuals

Pregnancy

Polysorbate is generally considered safe for use during pregnancy, but consult with a healthcare provider for specific cases.

Breast-feeding

Polysorbate is considered safe during breastfeeding, but consult with a healthcare provider for individual advice.

Storage

Store at room temperature, away from direct sunlight and moisture.

Formulations

• Polysorbate 20
• Polysorbate 80

Indications

• Plant growth regulation
• Agricultural applications as a growth inhibitor

Dosage

Children: Not applicable.

Adults: Refer to the relevant agricultural guidelines for specific applications.

Mechanism of action

In an in vitro study, propylene acts as a plant growth inhibitor by inhibiting the oxidation of indole-3-acetic acid by peroxidase in the presence of superoxide anion radicals. This inhibition is linked to the activation of an iron complex (compound III) shuttle, which enhances the reaction rate between superoxide and peroxidase, ultimately affecting plant growth processes. Propylene is a less effective inhibitor compared to ethylene.

Pharmacodynamics

The pharmacodynamic effects of propylene are primarily observed in its role as a growth inhibitor in plants. By modulating the oxidation of phytohormones like indole-3-acetic acid, propylene can influence various growth responses in plants, potentially affecting processes such as cell elongation and division.

Pharmacokinetics

Information on the pharmacokinetics of propylene in humans is not well-documented, as its primary uses are industrial and agricultural. Its metabolism may be influenced by environmental factors, and its effects are primarily studied in the context of plant biology rather than human pharmacology.

Dosage

Children: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Adults: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Mechanism of action

The mechanism of action for purified compounds varies widely depending on the specific substance. Generally, purified drugs exert their effects by interacting with specific biological targets, such as receptors, enzymes, or ion channels, leading to a desired therapeutic effect. This interaction can involve binding to receptors to activate or inhibit signaling pathways, modulating enzymatic activity, or altering physiological processes.

Pharmacodynamics

Pharmacodynamics describes the effects of a drug on the body and the relationship between drug concentration and effect. For purified drugs, this can involve dose-response relationships and the time course of their action. The purified form often enhances potency and reduces variability in response among patients, which can lead to more predictable therapeutic outcomes. The overall effect is determined by the drug's affinity for its target, the efficacy of the drug-receptor interaction, and the downstream signaling pathways activated as a result of this interaction.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of a drug. For purified substances, absorption can be more efficient due to the absence of impurities that may affect solubility or stability. Distribution may also be enhanced, leading to higher bioavailability. Metabolism can be influenced by the structure of the purified compound, as it may be metabolized more readily by liver enzymes. Excretion typically occurs through the kidneys or liver, depending on the molecular characteristics of the purified drug.

Pregnancy

Consult with a healthcare professional, as the safety of purified forms of medications during pregnancy may vary depending on the specific substance.

Breast-feeding

Consult with a healthcare professional, as the safety of purified forms of medications during breastfeeding may vary depending on the specific substance.

Storage

Store in a cool, dry place, away from light and moisture, and keep out of reach of children.

Mechanism of action

Ethylene glycol is metabolized by alcohol dehydrogenase to glycoaldehyde, which is then metabolized to glycolic, glyoxylic, and oxalic acids. These acids, along with excess lactic acid are responsible for the anion gap metabolic acidosis. Oxalic acid readily precipitates with calcium to form insoluble calcium oxalate crystals. Tissue injury is caused by widespread deposition of oxalate crystals and the toxic effects of glycolic and glyoxylic acids.

Mechanism of action

In an in vitro study of the mechanism of action of ethylene as a plant growth inhibitor, the effects of ethylene and some of its analogs, including propylene, on the oxidation of indole-3-acetic acid were examined. Ethylene and its analogs inhibited the oxidation of indole-3-acetic acid by peroxidase under conditions where the iron complex (compound III, an oxy-ferrous complex of peroxidase) shuttle was activated. Inhibition occurred only in the presence of the superoxide anion radical 02(-). Spectral and kinetic data indicated that ethylene and its analogs enhanced the rate of reaction of 02(-) with peroxidase; ie, the iron complex (compound III) shuttle, resulting in the formation of compound III. Propylene was a less effective inhibitor than ethylene.