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

Oil in water emulsion skin care