Lotion Definition in Pharmacy

What is a lotion in pharmacy?

Simple suspensions or solutions of drugs in water, alcohol, or other liquids are called lotions, and these preparations are primarily used to wash or apply to undamaged skin surfaces. When the lotion stays on the skin, a drug film is left on the surface of the skin as the liquid component evaporates. According to its dispersion system, the lotion can be divided into solution type, suspension type, emulsion type and many other types, among which suspension is the most common. Lotions are generally more fluid and less greasy than creams and ointments, which makes them easier to apply and absorb into the skin. The main purpose of lotions is to effectively deliver therapeutic agents to the skin, providing moisturizing, soothing, and medicinal benefits. Carefully designed emulsion formulations ensure optimal absorption and efficacy of the active ingredients while giving the product the desired beauty effect. The application of lotion is extremely wide, from skin disease treatment to beauty skin care has its figure.

Preparation of lotion

The preparation of lotions is a meticulous job that requires a deep background in pharmaceutical science, including knowledge in the fields of chemistry, biology, and materials science. The formulation process can be roughly divided into the following key steps:

Selection of ingredients

Active ingredient: Responsible for providing the desired efficacy.

Emulsifier: A mixture that helps stabilize the oil and water phases.

Humectants: Attract and retain moisture.

Preservatives: Prevent microbial growth and extend product shelf life.

Fragrances and colorants: Optional additives used to enhance the beauty of the product.

Formulation of emulsion

Oil phase preparation: Heating and mixing oil-soluble components.

Aqueous phase preparation: Heat and mix water-soluble ingredients.

Emulsification process: The oil phase and water phase are mixed under controlled conditions, usually using high shear mixing equipment to achieve uniform dispersion.

Homogenization

In order to ensure the consistency and stability of the emulsion, homogenization is required. This process helps to reduce the size of the dispersed droplets, thereby optimizing the texture and absorption properties of the emulsion.

Active ingredient addition

Active ingredients are precisely added to the base emulsion to ensure the stability and efficacy of the active agent.

Determination of lotion

A Flinn conductivity meter is used to measure the conductivity of each prepared lotion and some ingredients of the lotions. Using an ultraviolet lamp, the relative fluorescence is determined for each prepared lotion and the melted coconut oil. Equal masses of lotion and deionized water or sunflower oil are combined to assess solubility. Lotions are classified as acidic, basic, or neutral following testing with pHydrion paper.

Lotion example

Calamine lotion

Calamine menthol lotion

Calamine sulfur lotion

Diclofenac diethylamine lotion

Preparation of calamine lotion

Calamine lotion is a typical medicinal lotion containing calamine and zinc oxide as active ingredients. In addition, it contains bentonite, glycerin, sodium citrate and liquefied phenol. This lotion is known for its soothing and itchy properties. The preparation steps are as follows:

Ingredients of calamine lotion

Ingredients of calamine lotion. (Joy, N., 2022)

Preparation process

Preparation of suspension: Calamine and zinc oxide are dispersed in water to form a uniform suspension.

Adding bentonite slurry: Adding bentonite slurry to enhance the stability of the suspension.

Adding glycerin: Glycerin is mixed into the suspension to improve its moisturizing properties.

pH adjustment: Calcium hydroxide solution is used to adjust the pH to ensure the stability and therapeutic effect of the product.

Homogenization: The final mixture is homogenized to obtain a consistent and smooth emulsion.

Lotion formulation services at BOC Sciences

Pharmacological action of ingredient of calamine lotion

Calamine: Mainly contains zinc carbonate with a small amount of impurities such as calcium oxide, magnesium oxide, iron oxide and manganese oxide, as well as trace elements such as cobalt, copper, cadmium, lead and trace germanium and indium. It has mild, calming and antipruritic properties.

Zinc oxide: Zinc oxide is an inorganic powder with cooling and slight astringency that sooth and protects the skin. It is able to block a wide spectrum of light, including UVA and UVB as well as visible light, so it is used as an affordable physical sunscreen. Zinc oxide showed bactericidal action against Staphylococcus aureus and Pseudomonas aeruginosa. Zinc oxide also helps reduce skin tissue damage and itching and promotes the healing process.

Glycerin: Glycerin is a moisturizer that helps keep the skin moist and prevents dryness. It also acts as a moisturizing and stabilizing lotion, helping to form a protective layer and reducing external irritation.

Bentonite: A colloidal hydrated aluminosilicate that acts as a stabilizer in shaken emulsions, helping to maintain their suspension.

Liquified phenol: Used as a preservative, but its presence may make the lotion unsuitable for use by pregnant women and infants.

Sodium citrate: Used as a buffer or pH regulator to help maintain the stability of the emulsion.

Calamine lotion with added ingredients

Calamine lotion is found useful in many conditions due to its soothing and antipruritic actions. The addition of specific ingredients can render it antiparasitic, antifungal, and keratolytic effects. Menthol or camphor: These ingredients can enhance the anti-itch effect of calamine lotion while creating a cool feeling. Menthol is a cyclic terpenoid alcohol that reduces itching by acting on cold receptors and/or nerve fibers.

Diphenhydramine: This is an H1 histamine receptor antagonist that acts as a local anesthetic and works by blocking sodium channels.

Salicylic acid: When combined with calamine lotion, it can be used to treat intertrigo, a fungal infection of the folds of the skin.

Coal tar: The addition of coal tar can enhance the anti-itch effect of calamine lotion, and the concentration is 3%-5%.

Resorcinol: In concentrations between 1.2% and 3.6%, it increases the anti-parasitic, soothing and drying effects of calamine lotion and is suitable for some types of dermatitis.

Advantages of calamine lotion

When applied to the skin, the aqueous component of calamine lotion evaporates. The heat required for evaporation is taken from the body which gives a cooling effect at the site of application. This provides the lotion its soothing and antipruritic effect.

The powder added to the lotion increases the surface area of evaporation. As a result, the lotion effectively dries and cools wet and weeping skin.

It is suitable for application to large surface areas due to its ability to spread easily and uniformly.

Calamine lotion allows passage of some amount of secretion and exudation.

It is considered safe in pregnancy and lactation since it has been in use for centuries and has not been reported to cause any adverse outcomes in pregnancy or lactation. However, there is a lack of data from studies. However, phenol containing preparation is to be avoided in pregnant women.

It is often the favorite preparation in treating children and considered safe in infants. However, phenol containing preparation is to be avoided in infants.

By the addition of specific ingredients, the lotion can be made more effective in the management of different dermatoses.

Calamine lotion uses in dermatology

• Acute or subacute, less edematous, and less inflamed dermatoses or eczema.
• Dermatitis or eczema complicated by fungi (calamine lotion containing resorcinol).
• Eruptions of herpes zoster and drug eruptions (calamine lotion acts as a soothing agent).
• Crusted and excoriated stage of dermatitis herpetiformis.
• Lichen planus: Calamine lotion or its modifications with antipruritic action are useful to relieve pruritus associated with lichen planus.
• Pityriasis rosea: Calamine lotion or a simple modification of the same containing menthol and phenol may alleviate the pruritus of pityriasis rosea. The addition of 3–5% of solution of coal tar may improve the antipruritic effect and 1–3% of resorcinol may accelerate the desquamation of the rash.
• Sunburn.
• Miliaria, urticaria, insect bites, and stings (calamine lotion provides antipruritic and soothing effects).
• Acne vulgaris and other acneiform dermatoses.