#Making water viscosity thicker safe for skin skin
Formulae may have mixed ingredients with more than one type of vehicle.įactors in the choice of the vehicle or base for a topical medication include the nature of the skin complaint and its site.
Other terms used by cosmetic and pharmaceutical manufacturers include emulsion, paint, suspension, milk, syrup, collodion, balm and mist. May melt on reaching body temperature (eg, a suppository).ĭrug delivery system allows precise dosing: includes an adhesive. Solid, for example, talc (a mineral) or corn starch (vegetable).Īntiperspirant or sunscreen stick. Often includes preservatives and fragrances.Ī concentrated suspension of oil, water and powder. May include a hydrocarbon (paraffin), wool fat, beeswax, macrogols, emulsifying wax, cetrimide or vegetable oil (olive oil, arachis oil, coconut oil).Īqueous or alcoholic monophasic semisolid emulsion, often based on cellulose and liquefies upon contact with skin. No need for preservative, so contact allergy is rare. Greasy, sticky, emollient, protective, occlusive. Semi- solid, water-free or nearly water-free (80% oil). Requires preservative to extend shelf life. Thicker than a lotion, maintaining its shape, for example, a 50/50 emulsion of oil and water. A shake lotion separates into parts with time so needs to be shaken into suspension before use. Usually considered thicker than a solution and more likely to contain oil as well as water or alcohol. Water or alcoholic lotion containing a dissolved powder. Classification of topical formulations Solution Manufacturers interpret the definitions in various ways so a similar preparation might be called lotion, gel or cream. The table below describes different formulations.
The vehicle usually contains water, oil, alcohol or propylene glycol mixed with preservatives, emulsifiers, absorption promoters and fragrances. Topical formulations contain an active ingredient, often a medication or drug or botanical, and a vehicle. It takes 20–30 g of cream or ointment to cover an adult's total body once. One fingertip unit covers one side of 2 flat hands, and one gram covers both sides of the patient’s two hands. The fingertip unit (0.5 g) is a guide to the amount of a cream or ointment needed to treat an area for a certain time. It depends on:Įxpect 1 g of cream to spread out over a 10-cm 2 area of skin an ointment spreads a little further. How much topical medication to prescribe can challenge the most experienced dermatologist. Minor differences in the formulation may make surprising differences to the effectiveness of a topical medication. Other ingredients in the formulation may interact to increase or reduce potency or absorption rates.Higher concentrations of the active ingredient may penetrate more than lower concentrations.Lipophilic compounds are better absorbed than hydrophilic compounds.Small molecules are more easily absorbed through the skin than large molecules.The absorption of the active ingredient is greater where there is occlusion, such as in the skin folds, under dressings, or when a greasy, ointment formulation is used.Skin barrier function - this may be disrupted by dermatitis, ichthyosis, and keratolytic agents (such as salicylic acid), so it may absorb more medication than intact normal skin.
Thin skin absorbs more than thick skin - skin thickness varies with body site, age and the specific skin disorder.The amount of the active ingredient which is absorbed through the skin depends on the following factors: The product may be designed to be moisturising or to maximise the penetration of an active ingredient, often a medicine, into or through the skin. Topical formulations are made up in a vehicle, or base, which may be optimised for a particular site of the body or type of skin condition. The applications may also be messy or uncomfortable.At times, the regimen can be complicated, especially if several different formulations have been prescribed.There are reduced side effects and toxicity to other organs compared to systemic medications.ĭisadvantages of topical formulations include:.An increased dose of medication is applied where it is needed.Topical formulations are applied directly to the skin. General principles for topical formulations
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