into the blood circulation to any significant extent.
Topicals come as creams (water-based), ointments
(oil-based), gels, sprays, and liquids. Topical anal-
gesics may contain aspirin or other forms of salicy-
late, local anesthetic such as lidocaine (which
numbs the skin’s surface), hydrocortisone (an
anti-inflammatory DRUGto reduce swelling at the
skin’s surface), and capsaicin.
Suppository Rectal suppositories package the
medication in a soft, waxy capsule that, after
insertion into the RECTUM, melts to release the
analgesic. The rectal mucosa (mucous membrane
lining of the rectum) has a rich blood supply that
rapidly draws in the medication. Analgesics in
suppository form are especially effective when
nausea is a problem and for people who have dif-
ficulty swallowing.
Injection The more potent analgesics, notably
narcotics, are poorly absorbed through the gas-
trointestinal tract and thus are available in
injectable forms (shots). An injection may be
- intravenous (directly into a VEIN), which pro-
vides the most rapid (usually seconds) though
short-term (30 minutes to 2 hours) pain relief - intramuscular (into a muscle), which provides
fast relief (within 10 minutes) that can last
three to four hours - subcutaneous (into the layer of fatty tissue
beneath the skin), which provides prompt relief
(within 20 to 30 minutes) but slower release of
the medication into the blood circulation for
analgesia that can last six to eight hours - PATIENT-CONTROLLED ANALGESIA (PCA), in which
intravenous medication flows steadily into a
vein (intravenous administration) via a pump
that regulates the amount of medication, either
as at a preset rate or by patient demand (when
the person presses the button to release more
medication) - continuous infusion of local anesthesia, which
infiltrates tissue in a specific area with an anes-
thetic agent that relieves pain by numbing the
nerves such as after a surgical OPERATION - intrathecal analgesia, in which the pain special-
ist inserts a thin catheter into the space around
theSPINAL CORDthat delivers the analgesic in
somewhat the same fashion as PCA
PCA and intrathecal analgesia offer highly
effective pain control for ACUTE PAINafter surgery
as well as severe pain due to chronic or terminal
conditions. Continuous infusion of local anesthe-
sia is especially effective after major surgery,
reducing the amount of narcotic analgesics neces-
sary to provide adequate pain relief. Continuous
infusion of local anesthesia also allows greater
comfort for coughing, deep BREATHING, and return
to mobility, factors that are essential for HEALINGas
well as to prevent postoperative complications.
Injections can cause discomfort and bleeding at
the injection site.How These Medications Work
Analgesic medications work by altering how the
NERVOUS SYSTEMprocesses pain messages. They may- raise the pain threshold (the point at which
nociceptors perceive stimuli as painful); aceta-
minophen functions in this way - block production of PROSTAGLANDINSand other
biochemicals that sensitize nociceptors and acti-
vate the inflammatory response; NSAIDs func-
tion in this way - bind with neuroreceptors in the BRAINto alter
the brain’s interpretation of pain signals; opi-
ates and other narcotics function in this way - alter the balance of peripheral and central
(brain) neurotransmitters; antidepressants and
antiseizure medications function in this way - change the ionization of cells to affect how
molecules pass through them; beta blockers
and calcium channel blockers function in this
way
Taking analgesic medications properly is as
important as the correct choice of drug when it
comes to effective pain relief. Some analgesics
need to be taken on a scheduled basis because
they are more effective when they reach a steady
THERAPEUTIC LEVELin the blood. These medications
generally provide sustained pain relief for short-
term acute pain due to trauma or surgery and for
long-term CHRONIC PAIN. Other analgesics are more
effective when taken as needed, often indicated as
“prn” in the doctor’s instructions. These medica-
tions generally cover mild to moderate acute painanalgesic medications 367