It is very easy to take the “pro” side of this debate as, in essence, all topical dermatologic preparations are compounded. That is, they represent an active drug and preservatives in an appropriate base or vehicle.3 Topical therapy has two goals: (1) to administer a drug directly to the site of the disease, and (2) to avoid systemic absorption. In reality, all topically applied drugs are absorbed to some extent. Factors that affect systemic absorption are both patient/site specific and drug/vehicle specific. It is a basic principle of dermatologic therapy that topically applied drugs are absorbed more readily through inflamed, thin skin than through non-inflamed, thick skin. Experience has taught us that drug-induced Cushing's syndrome from topically applied corticosteroids occurs much more readily in erythrodermic patients than in those with plaque-type psoriasis. Hypercalcemia secondary to application of calcipotriene (a rare phenomenon) also has been noted primarily in the erythrodermic subset of psoriasis patients.2 Additionally, absorption of drugs occurs more efficiently from an ointment or gel vehicle than from a cream or solution. Not surprisingly, identical steroid preparations are assigned different potency rankings (as determined by the vasoconstrictor assay), depending on whether they are studied in the ointment or cream vehicle.Dr. Ling1 has stated in some of his previously published work, “Far from being merely an inert carrier, the vehicle is the key to a successful topical medication.”1 Many drug companies have recently formulated “optimized vehicles,” which they claim enhance potency and decrease side effects. Additionally, these “optimized vehicles” serve to protect the patents of our colleagues in the pharmaceutical industry, as they help differentiate their products from generic competition. As an example, Diprosone (Schering Corporation, NJ) (topical .05% betamethasone dipropionate) in its various formulations seemed to work very well until the manufacturer decided to bring us an “optimized vehicle” to enhance efficacy. Curiously, this event coincided with the advent of generic competition. Similarly, for two decades the manufacturer of Retin-A (tretinoin) has attempted to convince us that its various formulations were at the cutting edge of acne therapy; nevertheless, they have recently introduced a new microsphere preparation. In all fairness to these companies, the new preparations do offer some advantages over their predecessors. How vehicles are optimized is not very well publicized, as the manufacturers themselves do not want these “optimized vehicles” duplicated.As previously stated, all topical preparations are compounded, i.e., they involve a combination of ingredients including the active drug, preservatives, and the vehicle. Certainly, there are risks to extemporaneous compounding.1 There may be unwanted interactions between the drug and the vehicle leading to degradation of the drug or the vehicle.1 Compounding may alter the concentration of not only the drugs themselves, but also of the preservatives.1 For example, a combination of 0.1% triamcinolone ointment and an equal amount of Aquaphor will reduce the concentration of the triamcinolone to 0.05%, or half the original concentration, with perhaps a concomitant decrease in effectiveness. Similarly, the concentration of preservatives, which help counteract bacterial contamination, may be decreased by the compounding process. Presumably, manufacturers of topical preparations take these factors into consideration when formulating their products for commercial consumption. However, compounding does have certain benefits. It allows the physician to individualize treatment to the patient's specific needs and to abrogate a therapeutic vacuum, i.e., to create topical preparations that are not profitable enough for commercial manufacture.In the end, historic data may be the only reliable guide to the efficacy and safety of an extemporaneous formulation. Without extemporaneous compounding, the patient with psoriasis would have no tar preparations, the patient with cutaneous T-cell lymphoma would have no nitrogen mustard ointment, the patient who itches would have no phenol/menthol lotions, the patient with a scaly dermatosis would have no keratolytic lotions, the patient with alopecia areata would have no topical sensitizers, the patient with sun-damaged skin would have no trichloroacetic acid or phenol peeling solutions, and the dermatologic surgeon would have no topical hemostatics, such as aluminum chloride solution. Unfortunately, the pharmaceutical industry does not produce all of the topical preparations needed by dermatologists or their patients. Extemporaneous compounding is a fact of life that remains a necessity even as we approach the 21st century. There is no reason that dermatologists cannot practice this art, as long as they give due consideration to the actions and interactions of the components of their favorite formulations.
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Jan 1, 2013
Pavan Balabathula 
Open Access
