CALAMINE LOTION

Indications

• Constipation
• Bowel cleansing

Dosage

Children: Child 1–11 months: 1 g as required, Child 1–11 years: 2 g as required, Child 12–17 years: 4 g as required.

Adults: 4 g as required, usually administered rectally.

Mechanism of action

When administered rectally, glycerol exerts a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and reflexively stimulating evacuation. It decreases intraocular pressure by creating an osmotic gradient between the blood and intraocular fluid, causing fluid to move from the aqueous and vitreous humors into the bloodstream. Glycerol is classified as a hyperosmotic laxative and may also have lubricating and fecal softening effects.

Pharmacodynamics

Glycerol is commonly classified as an osmotic laxative, acting through its local irritant effects and possibly having lubricating and fecal softening actions. Glycerol suppositories usually produce effects within 15 to 30 minutes, providing quick relief from constipation.

Pharmacokinetics

Glycerol is rapidly absorbed through the gastrointestinal tract. It is metabolized in the liver and other tissues, with a half-life that varies depending on the route of administration. Following rectal administration, glycerol is primarily excreted in urine. The pharmacokinetics may vary based on dosage forms and individual patient factors.

Contra-indications

• Acute abdominal conditions
• Acute inflammatory bowel disease
• Intestinal obstruction
• Severe dehydration

Adverse effects

• Abdominal cramps
• Asthenia
• Gastrointestinal disorders
• Hypermagnesaemia
• Skin reactions
• Urine discolouration

Precautions

• Avoid prolonged contact with skin, especially in incontinent patients or infants wearing nappies due to the risk of irritation and excoriation.
• Excessive use may cause diarrhea and related effects such as hypokalaemia.

Pregnancy

Manufacturers advise avoidance due to limited information available.

Breast-feeding

Manufacturers advise avoidance as there is no information available.

Storage

Store at room temperature, away from direct sunlight.

Formulations

• Glycerol 1g suppositories
• Glycerol 2g suppositories
• Glycerol 4g suppositories
• Glycerol oral suspension

Indications

• Rectal and anal disorders
• Haemorrhoids
• Pruritus ani

Dosage

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

Adults: For rectal use using aerosol spray: 1 spray up to 3 times a day for no longer than 7 days without medical advice. For ointment: apply several times daily, for short-term use only.

Mechanism of action

Phenol exerts its effects by acting as a potent proteolytic agent. At concentrations of 5% to 7%, it can dissolve tissue through proteolysis. When injected near a nerve, it produces chemical neurolysis, affecting nerve fibers nonselectively. Local anesthetic effects are typically observed within 5 to 10 minutes of application.

Pharmacodynamics

Phenol's pharmacodynamic properties include its ability to cause tissue dissolution and local anesthesia. The local anesthetic effects result from its action on the nerve fibers, leading to a temporary loss of sensation in the affected area. The proteolytic action can assist in the treatment of various skin and mucosal conditions by facilitating tissue breakdown.

Pharmacokinetics

Phenol is absorbed through mucosal surfaces when applied locally. Its metabolism involves biological oxidation and phase I functionalization, primarily through cytochrome P450 enzymes. The elimination of phenol occurs through metabolic pathways, and it can be detected in urine as a result of its metabolism.

Contra-indications

• Infection
• Known hypersensitivity to phenol or its components

Adverse effects

• Local irritation
• Burning sensation
• Paraesthesia
• Vision disorders
• Skin reactions
• Adrenal suppression

Interactions

• Caution with other local anesthetics due to potential additive effects

Precautions

• Use for short periods only-no longer than a few days
• Avoid excessive application, especially on sensitive areas
• Consult product literature for specific guidelines

Pregnancy

Data on the use of phenol during pregnancy is limited; caution is advised.

Breast-feeding

Limited information available; caution is recommended when used in breastfeeding mothers.

Storage

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

Formulations

• Ointment
• Suppository
• Aerosol spray

Indications

• Mild skin irritations
• Insect bites
• Sunburn
• Rashes
• Prickly heat

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines based on age and condition.

Adults: Apply to the affected area as needed, usually 2 to 4 times daily.

Mechanism of action

Calamine exerts its effects mainly through the astringent properties of zinc oxide and the soothing effects of ferric oxide. It helps to dry out oozing and weeping skin, while also providing a cooling sensation to alleviate discomfort.

Pharmacodynamics

The pharmacodynamics of calamine involve its ability to act as a protective barrier on the skin, reducing irritation and discomfort associated with various skin conditions. The astringent properties help to reduce moisture and inflammation, making it effective for soothing skin irritations.

Pharmacokinetics

Calamine is applied topically and is not significantly absorbed into systemic circulation, which minimizes systemic side effects. Its local effects are immediate upon application, providing rapid relief from symptoms like itching and inflammation.

Pregnancy

Calamine is generally considered safe for use during pregnancy, as it is a topical agent with limited systemic absorption.

Breast-feeding

Calamine is also considered safe for use during breastfeeding, as it is unlikely to pose a risk to the nursing infant.

Storage

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

Formulations

• Calamine lotion
• Calamine cream

Mechanism of action

Oxides do not have a single mechanism of action as they are a broad category of compounds. However, in general, metal oxides can exhibit catalytic properties, while non-metal oxides may participate in biochemical reactions by forming acids or bases upon dissolution in water.

Pharmacodynamics

The pharmacodynamics of oxides depend on the specific type of oxide and its interaction with biological systems. For instance, metal oxides may have antimicrobial properties, while certain non-metal oxides can influence metabolic pathways through their acid-base chemistry. The effects vary widely, necessitating specific studies for each oxide's role in therapeutic contexts.

Pharmacokinetics

The pharmacokinetics of oxides are also variable. Many metal oxides are poorly soluble and thus have limited absorption when ingested. Non-metal oxides, such as carbon dioxide, can be readily absorbed and utilized in metabolic processes. The distribution, metabolism, and excretion of oxides depend on their chemical form and the biological system in which they are involved.

Pregnancy

Not applicable as oxide is not a drug but a class of chemical compounds.

Breast-feeding

Not applicable as oxide is not a drug but a class of chemical compounds.

Storage

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

Mechanism of action

When administered rectally, glycerin exerts a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and reflexively stimulating evacuation. Glycerin decreases intraocular pressure by creating an osmotic gradient between the blood and intraocular fluid, causing fluid to move out of the aqueous and vitreous humors into the bloodstream. Glycerin (glycerol) and sorbitol are hyperosmotic laxatives. When administered rectally, glycerin and sorbitol exert a hygroscopic and/or local irritant action, drawing water from the tissues into the feces and reflexly stimulating evacuation. The extent to which the simple physical distention of the rectum and the hygroscopic and/or local irritant actions are responsible for the laxative effects of some of these drugs is not known. Only extremely high oral doses of sorbitol (25 g daily) or glycerin exert laxative action. /Glycerin/ decreases intraocular pressure by creating an osmotic gradient between the blood and intraocular fluid, causing fluid to move out of the aqueous and vitreous humors into the bloodstream. The physicochemical effects of a series of alkanols, alkanediols and glycerol on erythrocyte shape and hemolysis at 4 and 20 degrees C were examined. We calculated the dielectric constant of the incubation medium, Ds, and the dielectric constant of the erythrocyte membrane Dm in the presence of organic solutes. The ratio Ds/Dm = -38.48 at 20 degrees C defines the normal biconcave shape in a medium without hemolytic agents. A decrease in Ds/Dm favors externalization or internalization with consequent hemolysis. Alkanols and alkanediols convert biconcave erythrocytes into echinocytes, which is accompanied by an increase in the projected surface area. Glycerol converts biconcave erythrocytes into stomatocytes, which was accompanied by a marginal decrease in the projected surface area. Progressive externalization in alkanols and alkanediols or internalization in glycerol resulted in a decrease in the projected surface area and the formation of smooth spheres. The degree of shape change induced was related to the degree of hemolysis and the ratio Ds/Dm. A decrease in temperature reduced both the degree of shape change and hemolysis. .../Thus/ physicochemical toxicity may be a result of a temperature dependent hydrophobic interaction between the organic solutes and the membrane and is best interpreted by the ability of the solutes to change Ds and Dm.

Pharmacodynamics

Glycerin is commonly classified as an osmotic laxative but may act additionally or alternatively through its local irritant effects; it may also have lubricating and fecal softening actions. Glycerin suppositories usually work within 15 to 30 minutes.

Mechanism of action

Phenol is a potent proteolytic agent. Concentrations in the 5% to 7% range dissolve tissue on contact via proteolysis. In high concentrations when injected next to a nerve, phenol produces a chemical neurolysis which is nonselective across nerve fiber size and most prominent on its outer aspect. Local anesthetic effects occur within 5-10 minutes. The effects of monoamine depletors and monoamine denervators on phenol induced tremor were studied in mice. The tremor induced by phenol was enhanced by pretreatment with reserpine or tetrabenazine, but not with syrosingopine. However, alpha-methyl-p-tyrosine, p-chlorophenylalanine or 6-hydroxydopamine did not affect the tremor. These results suggest that the depletion of central monoamines as a whole contribute to the enhancement of the tremor induced by phenol.