Prescribing by generic
name offers the pharmacist flexibility in selecting the particular drug product
to fill the order and offers the patient a potential savings when there is
price competition. For example, the brand name of a popular sedative is Valium, manu-factured by
Hoffmann-LaRoche. The generic (public nonpropri-etary) name of the same
chemical substance adopted by United States Adopted Names (USAN) and approved
by the FDA is diaz-epam. All diazepam
drug products in the USA meet the pharma-ceutical standards expressed in the United States Pharmacopeia(USP). However,
there are several manufacturers, and prices varygreatly. For drugs in common
use, the difference in cost between the trade-named product and generic
products varies from less than twofold to more than 100-fold.
In most states and in
most hospitals, pharmacists have the option of supplying a generically
equivalent drug product even if a proprietary name has been specified in the
order. If the prescriber wants a particular brand of drug product dis-pensed,
handwritten instructions to “dispense as written” or words of similar meaning
are required. Some government-subsidized health care programs and many
third-party insur-ance payers require
that pharmacists dispense the cheapest generically equivalent product in the
inventory (generic sub-stitution). However, the principles of drug product
selection by private pharmacists do not permit substituting one thera-peutic
agent for another (therapeutic substitution); that is, dispensing
trichlormethiazide for hydrochlorothiazide would not be permitted without the
prescriber’s permission even though these two diuretics may be considered
pharmacody-namically equivalent. Pharmacists within managed care orga-nizations
may follow different policies;.
cannot be assumed that every generic drug product is as satisfactory as the
trade-named product, although examples of unsatisfactory generics are rare.
Bioavailability—the effective absorption of the drug product—varies between
manufacturers and sometimes between different lots of a drug produced by the
same manufacturer. In spite of the evidence, many practitioners avoid generic
prescribing, thereby increasing medical costs. In the case of a very small
number of drugs, which usually have a low therapeutic index, poor solubility, or
a high ratio of inert ingredi-ents to active drug content, a specific
manufacturer’s product may give more consistent results. In the case of
life-threatening dis-eases, the advantages of generic substitution may be
outweighed by the clinical urgency so that the prescription should be filled as
In an effort to codify bioequivalence information, the FDA publishes Approved Drug Products with Therapeutic Equivalence Evaluations, with monthly supplements, commonly called “theOrange Book.” The book contains listings of multi-source products in one of two categories: Products given a code begin-ning with the letter “A” are considered bioequivalent to a refer-ence standard formulation of the same drug and to all other versions of that product with a similar “A” coding. Products not considered bioequivalent are coded “B.” Of the approximately 8000 products listed, 90% are coded “A.” Additional code let-ters and numerals are appended to the initial “A” or “B” and indicate the approved route of administration and other variables.
Mandatory drug product
selection on the basis of price is common practice in the USA because
third-party payers (insur-ance companies, health maintenance organizations,
etc) enforce money-saving regulations. If outside a managed care organiza-tion,
the prescriber can sometimes override these controls by writing “dispense as
written” on a prescription that calls for a brand-named product. However, in
such cases, the patient may have to pay the difference between the dispensed
product and the cheaper one.
most managed care organizations, formulary controls have been put in place that
force the selection of less expensive medications whenever they are available.
In a managed care envi-ronment, the prescriber often selects the drug group
rather than a specific agent, and the pharmacist dispenses the formulary drug
from that group. For example, if a prescriber in such an organiza-tion decides
that a patient needs a thiazide diuretic, the pharma-cist automatically
dispenses the single thiazide diuretic carried on the organization’s formulary.
As noted below, the choice of drugs for the organization’s formulary may change
from time to time, depending on negotiation of prices and rebates with
The private pharmacy
bases its charges on the cost of the drug plus a fee for providing a
professional service. Each time a prescription is dispensed, there is a fee.
The prescriber con-trols the frequency of filling prescriptions by authorizing
refills and specifying the quantity to be dispensed. However, for medications
used for chronic illnesses, the quantity covered by insurance may be limited to
the amount used in 1 month. Thus, the prescriber can save the patient money by
prescribing standard sizes (so that drugs do not have to be repackaged) and,
when chronic treatment is involved, by ordering the largest quantity consistent
with safety, expense, and third-party plan. Optimal prescribing for cost
savings often involves consultation between the prescriber and the pharmacist.
Because of continuing increases in the whole-sale prices of drugs in the USA,
prescription costs have risen dramatically over the past 3 decades; and from
1999 to 2009, the number of prescriptions purchased has increased 39% while the
population grew 9% (see Box: The Cost of Prescriptions).