Manual of Dermatologic Therapeutics
7th Edition

The prescribing of medications today is very different from the early 1900s, when most medications were compounded on the basis of physicians’ recipes. Currently, hundreds of single-ingredient as well as multiple-ingredient products are available to the dermatologist, both in prescription and over-the-counter forms. The fixed-dose combination products can offer effective alternatives to extemporaneous products compounded by the pharmacist. A wide range of fixed-dose products are now available, many offering comparable therapeutic benefits but at different costs. A major factor to influence price is whether the product is generic or branded. A drug manufacturer has exclusive rights to a compound it develops for the first 17 years after discovery (not market entry, but creation and patenting of the chemical entity). This product will possess a commercial brand name, making it readily identifiable, and a generic chemical name. Only the brand name is available until the patent expires, unless the company signs a licensing agreement with another firm. Once patent expiration occurs, generic forms are manufactured and available to the market. In most states, once a U.S. Food and Drug Administration (FDA)-approved generic product is available, the pharmacist must dispense the less expensive version unless the physician specifically writes “no substitution” or “dispense as written” or checks the appropriate box on the prescription. In most cases, generic products are less expensive than brand-name versions, but the difference can range from as little as pennies to as much as 50% to 80%. The exception to this is insurance arrangements where patients pay a fixed amount (co-pay) per prescription. This price may be less for a generic version or could be the same for all prescriptions. Although generics have to meet FDA specifications to be marketed as equivalent, permissible variations in the vehicle or base may produce alterations in products.

Another essential component of economically prudent prescribing is package size, where larger tubes (60 g) cost less per gram than smaller (15- or 30-g) ones. Although there are books available listing the retail pharmacies’ acquisition costs of medications (Drug Topics Red Book and American Druggist Blue Book), these become outdated quickly because of the twice-yearly price changes from drug manufacturers. The most accurate way to gauge patient cost is to speak to your local pharmacist. The retail marketplace for prescriptions is very competitive, with an average profit on a prescription of approximately 20% (i.e., the pharmacy acquires the drug for $20 and sells it for $24). As a rule, generic drugs cost, on average, 30% to 40% less than brand names. By working closely with neighboring pharmacies and using a consistent selection of prescription products, the pharmacist will be more likely to carry the products you prescribe, often purchasing them in volume and providing them at a lower cost to your patients. Lastly, be sure to write all prescriptions with explicit directions for use, including duration of treatment when applicable. The pharmacist will put this on the medication label, preventing any confusion or errors in patient understanding.

It is important to note that there are two variables in topical therapy. Both the medication and the vehicle chosen must be appropriate for the condition being treated. In general, acute inflammation is treated with aqueous drying preparations, and chronic inflammation
is treated with greasier, more lubricating compounds (see also Chap. 40, Dermatologic Topical Preparations and Vehicles).

It will become apparent on long-term patient follow-up that when inadequate amounts of medication are dispensed, the patient will tend to apply too little, will use the drugs less frequently than prescribed, will soon run out of medication, and then may not refill the prescription. If a medication is known to be effective and is to be used on a long-term basis, dispensing large quantities will be more economical and will ensure continuous supply, resulting in better treatment.

One gram of cream will cover an area of skin approximately 10 cm by 10 cm, or approximately 100 sq. cm, assuming a layer 100 μm in thickness. The same amount of ointment will cover an area 5% to 10% larger. Total body self-application of different vehicles was studied in 29 adults and found to average 22 g. Subjects used twice as much medication from a large jar than from a small tube. Table 39-1 gives conservative figures for the amounts needed for a single application of an ointment or cream and for t.i.d. application for a 2-week period.

The fingertip unit (FTU) is a practical, visually simple means of explaining how much ointment is adequate to cover a specific region. One FTU is the amount of ointment expressed from a tube with a 5-mm-diameter nozzle applied from the distal skin crease to the tip of the index finger, roughly equivalent to 0.5 g. The area of involved skin covered by one flat, closed hand requires approximately 0.5 FTU, or 0.25 g, of ointment. Four hand areas require 2 FTUs, or 1 g, of ointment. Also, the number of ounces of ointment needed for one application per day equals the number of grams needed for a single application.

Recommendations for the care of normal skin are based on principles of moderation and common sense as well as on knowledge derived from the study of skin structure and function. Routine daily care is far simpler than one may be led to believe by the profusion of astounding advertising claims. Whereas much is known about adverse reactions to cosmetics and other products for topical use, well-controlled scientific studies related to the care and maintenance of healthy skin are either so limited or so rudimentary that they preclude precise recommendations in most instances. “Normal” skin refers to skin that is not affected by any disease process. Within “normal,” there is obviously a wide variation of skin textures, complexions, and appearances. The principles in this section are applicable to almost everyone within this category, whether the skin is on the “dry” or the “oily” end of the spectrum. The various systems and categorizations of skin types so readily available at cosmetic counters of department stores yield little useful information, are not based on any basic pathophysiologic principles, and are useful primarily for the cosmetic company whose products are subsequently recommended. It is not at all clear that normal skin benefits from much, if anything at all, in the way of specific care, except for protection from harsh chemical and physical agents (especially sunlight). On the other hand, many products used for skin care or cosmetic purposes can occasionally produce adverse reactions, such as allergic and irritant contact dermatitis, phototoxic and photoallergic reactions, and induction of acne (acne cosmetica). Neither price range nor brand name provides absolute assurance that a given product will be of high quality or will not cause adverse reactions. The area of skin care is beset with an amazing number of unsubstantiated claims, “secret” ingredients, and fads. It is beyond the scope of this book to address all of them.