L–N
legend drug In the United States, any DRUGthat
requires a physician or other appropriately
licensed health-care provider (such as a dentist,
optometrist, or podiatrist) to write a prescription
and a pharmacist to dispense the medication. The
federal approval and regulatory process deter-
mines which drugs are legend drugs, the labels of
which must carry the admonition, “Caution: Fed-
eral law prohibits dispensing without a prescrip-
tion.” Each state further regulates the prescribing
and dispensing of legend drugs, though practices
are fairly consistent across states. Such regulation
includes the kind of information that must appear
on the dispensing label and the manner in which
the pharmacist must discuss the drug’s intended
benefits and potential risks with the person receiv-
ing the medication. It is common to refer to leg-
end drugs simply as prescription drugs.
See also OFF-LABEL USE; OVER-THE-COUNTER(OTC)
DRUGS; SCHEDULED DRUG.
low-cost prescription programs Need-based
programs, usually under the sponsorship of major
pharmaceutical manufacturers, that make certain
prescription medications available to people who
lack insurance coverage for prescription medica-
tions or who cannot otherwise afford to obtain
them. Most low-cost prescription programs have
income limitations for enrollees and many require
that a doctor refer the person and that the person
receive the medications through delivery to the
doctor’s office. Doctors, hospitals, and pharmacies
maintain information about current programs and
their enrollment requirements.
Some organizations, such as the American
Association for Retired Persons (AARP), also have
membership prescription programs that make
drugs available to members at a significant dis-
count from regular retail prices. Doctors’ offices
and clinics hospitals also often have drug samples
that pharmaceutical representatives leave. Some
programs offer prepaid prescription cards and
other kinds of membership promotions for people
who do not have insurance to cover prescription
drugs but exceed the income levels for low-cost
prescription plans. Whether these programs truly
save money on prescription drugs depends on the
amount and kinds of prescription drugs an indi-
vidual takes.
See also HEALTHYPEOPLE 2010 ; ORPHAN DRUG.narrow therapeutic index (NTI) A very close
margin between the concentration in the BLOOD
circulation of a DRUGthat is therapeutic and the
concentration that is lethal (deadly). Pharmacists
generally express the therapeutic index as a ratio
between the median effective DOSE(ED50) and the
median lethal dose (LD50). A drug has a narrow
therapeutic index when there is less than a
twofold difference between the ED50 and the
LD50. With NTI drugs even very small changes in
the dose, variations in product potency, or
changes in the person’s health status can result in
toxic levels of the drug with harmful or fatal con-
sequences.
The current standard of practice is to maintain
the course treatment with the same drug product
rather than substituting across brand and generic
products as commonly and safely occurs with
non-NTI drugs. Some doctors prefer to use specific
brand name products when prescribing NTI drugs.
Some states mandate a nonsubstitution standard
via law or regulatory code, requiring pharmacies
to dispense the original drug product. Some clini-
cal studies support such caution though others
suggest that, at least with some NTI drugs, generic161