Franklin had-3018 Guida Utente

MECHANISMS OF INTERACTIONS —
Genetic differences can affect drug metabolism
and interactions. Some drugs can interact by
changing the metabolism of other drugs, either
through inhibition or induction of any of sev-
eral hepatic enzyme activities or through alter-
ations in hepatic blood flow. Many drugs are
metabolized by cytochrome P450 isozymes.
These isozymes are named according to a stan-
dard system, e.g., CYP3A4 or P4503A4.
Drugs that are substrates or inhibitors for the
same isozyme in vitro are likely to interact, but
no interaction may be detectable, or it may not
be clinically significant. Other drugs alter the
binding of another drug to plasma proteins or
tissue receptors, alter the distribution of drugs
to active receptor sites, delay or enhance excre-
tion, or cause additive or synergistic effects.

RECOMMENDATIONS — Monitoring is
most important when one of the interacting
drugs is stopped or started. Some experienced
clinicians may prefer to monitor the patient’s
clinical status rather than follow serum concen-
trations of drugs. Concurrent use of drugs from
the same group, e.g., aspirin and other
NSAIDs, should be avoided.

Introduction to the HADI

) Displays interactions between

selected drug(s) and all other drugs
in this book.

) Displays a glossary entry.

) Searches for interactions

among the selected drugs.

) Lists the items currently se-

lected from the main drug list.

Erases typed letters, or backs up to
the previous screen.

Shifts keys to type capitals or punctuation.

Exits the currently selected book.

Clears your search and returns to
the main drug list.

Enters a word, selects a menu item,
or starts the highlight in text.

Displays help messages.

Displays the main menus.

Turns the platform on or off.

At menus and text, pages down. At
entry screens, types a space.

✻

At menus, displays the title of a high-
lighted item. At text, displays the current
entry title. With 

, types an asterisk

(✽) to stand for letters in a word.