Topical medication
Medication applied to a specific place on or in the body.
A topical medication is one applied to a specific location on or inside the body. These medications are most frequently used on the skin or mucous membranes and come in forms like creams, foams, gels, lotions, and ointments. Many are epicutaneous, meaning they go directly onto the skin. However, topical medications can also be inhaled (for example, asthma drugs), or applied to other tissue surfaces—such as eye drops on the conjunctiva, ear drops in the ear, or medicine painted onto a tooth. The word "topical" comes from the Greek *topikos*, meaning "of a place."
Historically, people used herbs placed on wounds to relieve inflammation or pain. Today, the topical drug delivery system is far broader, serving purposes from smoking cessation to cosmetic applications. This route of administration uses the skin—one of the largest and most superficial organs—to deliver drugs for a local therapeutic effect. Numerous dosage forms exist, including creams, ointments, lotions, patches, and dusting powders. Advantages include avoiding first-pass metabolism (which can increase bioavailability), convenience for application over large areas, ease of stopping treatment, and avoidance of gastrointestinal irritation, all of which improve patient compliance. Disadvantages include potential skin irritation, such as rashes and itchiness. Additionally, only small particles can pass through the skin, limiting drug choices. The skin’s condition—its temperature, pH, and dryness—directly affects the rate of drug penetration and, consequently, the drug’s pharmacokinetics.
Topical drug absorption depends on two major factors: biological and physicochemical properties. Biological factors include the application site, as different body areas show different absorption patterns. Age also matters, because aging skin has lowered collagen and broadened blood capillary networks, altering absorption of both hydrophilic and lipophilic substances into the stratum corneum. Skin surface integrity—such as the density of hair follicles or sweat glands, or damage from inflammation or dehydration—also affects permeability. Physicochemical factors involve drug metabolism on the skin. When a drug is applied, it is gradually absorbed and metabolized by enzymes, though degradation in skin is much lower than in the liver, since the metabolic enzyme cytochrome P450 is not very active there. Drugs metabolized
- field
- Pharmaceutical drug delivery
- known_for
- Route of administering drugs via the skin to provide topical therapeutic effects
- common_forms
- Creams, ointments, lotions, gels, foams, patches, dusting powders
- derivation
- Greek τοπικός topikos, 'of a place'
Lore & Background
Topical drug delivery is a route of administering drugs via the skin to provide topical therapeutic effects. As skin is one of the largest and most superficial organs in the human body, pharmacists utilise it to deliver various drugs. This system usually provides a local effect on certain positions of the body. In ancient times, people used herbs to put on wounds for relieving the inflammatory effect or as pain relievers. The use of topical drug delivery system is much broader now, from smoking cessation to beauty purposes. Nowadays, there are numerous dosage forms that can be used topically, including cream, ointment, lotion, patches, dusting powder and much more.
Reader's Guide
Topical medications are significant because they offer a localized route of drug administration that avoids first pass metabolism, increasing bioavailability, and are convenient and easy to apply. They can be terminated easily and avoid gastrointestinal irritations, improving patient compliance. However, they can cause skin irritations such as rashes and itchiness, and only small particles can pass through the skin, limiting drug choices. The condition of the skin—temperature, pH, and dryness—affects absorption. The definition of topical route sometimes states that both the application location and the pharmacodynamic effect are local; in other cases, it includes transdermal application for systemic distribution. The base formulation (cream vs. ointment) can change a medication's potency, and manufacturers have total control over the base, leading to possible variation between brands. In dermatology, the base is often as important as the medication itself.
Did You Know?
- The word topical derives from Greek τοπικός topikos, meaning 'of a place'.
- Topical medications can be inhalational, such as asthma medications, or applied to the conjunctiva as eye drops.
- The metabolism of topical drugs is mainly by cytochrome P450, which is not active in skin, allowing high concentrations of CYP450-metabolized drugs.
- Some topical steroids are classified one or two strengths higher when moving from cream to ointment.
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