Topical medication

Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes including creams, foams, gels, lotions, and ointments.

Nowadays, there are numerous dosage forms that can be used topically, including cream, ointment, lotion, patches, dusting powder and much more.

This localized system provides topical therapeutic effects via skin, eyes, nose and vagina[3] to treat diseases.

These features alter the effectiveness of absorption of both hydrophilic and lipophilic substances into stratum corneum underneath the surface of the skin.

[5] The skin surface integrity can also affect the permeability of drugs such as the density of hair follicles, sweat glands or disintegrated by inflammation or dehydration.

The drugs target cells underneath the skin or need to diffuse into blood capillary to exert their effect.

The definition of the topical route of administration sometimes states that both the application location and the pharmacodynamic effect thereof is local.

[7][8] By this definition, topical administration also includes transdermal application, where the substance is administered onto the skin but is absorbed into the body to attain systemic distribution.

Specific types include transdermal patches which have become a popular means of administering some drugs for birth control, hormone replacement therapy, and prevention of motion sickness.

One poorly absorbable antibiotic is vancomycin, which is recommended by mouth as a treatment for severe Clostridioides difficile colitis.

Although containing the same active ingredients, one manufacturer's cream might be more acidic than the next, which could cause skin irritation or change its absorption rate.

Some physicians use a thick ointment to replace the waterproof barrier of the inflamed skin in the treatment of eczema, and a cream might not accomplish the same clinical intention.

As a result, what the manufacturer's marketing department chooses to list on the label of a topical medication might be completely different from what the form would normally be called.

Creams have a significant risk of causing immunological sensitization due to preservatives and have a high rate of acceptance by patients.

These foams are typically simple to apply, which can lead to better patient compliance and, in turn, improve treatment results for those who favor a more convenient and cleaner topical option.

An ointment is a homogeneous, viscous, semi-solid preparation; most commonly a greasy, thick water-in-oil emulsion (80% oil, 20% water) having a high viscosity, that is intended for external application to the skin or mucous membranes.

They are used as emollients or for the application of active ingredients to the skin for protective, therapeutic, or prophylactic purposes and where a degree of occlusion is desired.

Ointments are formulated using hydrophobic, hydrophilic, or water-emulsifying bases to provide preparations that are immiscible, miscible, or emulsifiable with skin secretions.

Frequently, an oil mixed with a water-based solution needs to be shaken into suspension before use and includes the instructions: "Shake well before use".

Topical solutions can be marketed as drops, rinses, or sprays, are generally of low viscosity, and often use alcohol or water in the base.

[18][page needed] There is significant variability among brands, and some solutions may cause irritation, depending on the preservative(s) and fragrances used in the base.

Some examples of topical solutions are given below: Transdermal patches can be a very precise time released method of delivering a drug.

It is designed from the Biopharmaceutics Classification System (BCS) for oral immediate release solid drug products which is very successful for decades.

[21] In the early 1970s, the Alza Corporation, through their founder Alejandro Zaffaroni, filed the first US patents describing transdermal delivery systems for scopolamine, nitroglycerin and nicotine.

From a patient perspective, applying drugs on skin also provides stable dosage in blood so as to give the optimal bioavailability and therapeutic effects.

In case of overdose or unwanted side effects, patients can take off or wash out the medicines quickly to eliminate toxicity by simply removing the patch to stop the delivery of drugs.

Hence, some topical drugs including nicotine patches for smoking cessation are advised to change places for each application to avoid continuous irritation of the skin.

For example, this carrier can have a cooling, drying, emollient or protective action to suit the required conditions of the application site such as applying gel or lotion for hairy areas.

Chemists also need to consider the irritation or any sensitization potential to ensure that the topical application can be stable during storage and transport to maintain its efficacy.

[citation needed] It helps the gel to enter deeply down the skin layer to strengthen the delivery of diclofenac to the point of pain so as to achieve better therapeutic effects by modifying the above properties.