sea center. Antihistamine medications with H3
blocking capability thus cause drowsiness and
relieve nausea as well. Second-generation antihis-
tamine medications are selective. They block pri-
marily H1 receptors and have little effect on H3
receptors; thus they do not generally cause
drowsiness and provide little or no relief of nau-
sea. Third-generation antihistamine medications
derive from second-generation antihistamines and
are purported to have fewer side effects and
adverse reactions though functionally are no dif-
ferent. Many antihistamine medications are avail-
able in the United States as OVER-THE-COUNTER
(OTC) DRUGS, sometimes in combination with a
decongestant or other ingredients. Manufacturers
often market OTC antihistamines as allergy-relief
products. Other antihistamines require a doctor’s
prescription.
ANTIHISTAMINE MEDICATIONSFirst-Generation (Nonselective) Antihistamines
brompheniramine chlorpheniramine
dexchlorpheniramine dimenhydrinate
diphenhydramine doxylamine
hydroxyzine phenindamine
pheniramine pyrilamine
triprolidine
Second-Generation (Selective H1) Antihistamines
acrivastine azatadine
cetirizine clemastine
cyproheptadine loratadine
mizolastine
Third-Generation (Selective H1) Antihistamines
desloratadine fexofenadine
levocetirizine
Therapeutic ApplicationsDoctors prescribe or recommend antihistamine
medications to treat ALLERGIC RHINITIS, ALLERGIC
CONJUNCTIVITIS, and ALLERGIC DERMATITIS. Most of the
nonselective antihistamines cause significant
drowsiness; doctors prescribe or recommend them
for intermittent insomnia (difficulty sleeping).
Meclizine is an H3 receptor antihistamine effective
for nausea and VOMITING, especially that associated
with motion sickness. Meclizine has little effect on
H1 receptors, however, so does not influence the
immune response or relieve symptoms of hyper-
sensitivity reaction.
Some antihistamine medications have other
therapeutic applications, such as- anxiety: hydroxyzine
- sedative and sleep aid: diphenhydramine,
doxylamine, hydroxyzine - nausea and vomiting: dimenhydrinate, diphen-
hydramine, hydroxyzine - VERTIGO: dimenhydrinate, diphenhydramine
- early PARKINSON’S DISEASE: diphenhydramine
Risks and Side Effects
In general antihistamine medications cause few
side effects other than drowsiness, although can
raise BLOOD PRESSURE. People who take other med-
ications to treat chronic health conditions should
check with their doctors before taking antihista-
mines, as antihistamines can exacerbate symptoms
or interfere with the actions of other drugs.
See also ANTIBODY; ARTERY; CORTICOSTEROID MED-
ICATIONS; CAPILLARY BEDS; GENERALIZED ANXIETY DISOR-
DER(GAD); H 2 ANTAGONIST(BLOCKER) MEDICATIONS;
LIVING WITH ALLERGIES; LYMPHOCYTE; NEUROTRANSMIT-
TER; PROTON PUMP INHIBITOR MEDICATIONS; SNEEZE.antimitochondrial antibodies Autoantibodies
the IMMUNE SYSTEMproduces that attack the mito-
chondria within self cells. Mitochondria are the
organelles (functional structures) within a cell that
generate the energy the cell needs to carry out its
activities. Antimitochondrial antibodies are pro-
teins that bind with antigens (other proteins) on
the inner walls of the mitochondria, blocking the
ability of the mitochondria to convert oxygen to
energy. The cell dies as a result.CONDITIONS IN WHICH
ANTIMITOCHONDRIAL ANTIBODIES ARE PRESENT
CIRRHOSIS PRIMARY BILIARY CIRRHOSIS
PRIMARY SCLEROSING CHOLANGITIS RHEUMATOID ARTHRITIS
SYSTEMIC LUPUS ERYTHEMATOSUS(SLE) THYROIDITISA BLOODtest called the antimitochondrial ANTI-
BODY(AMA) titer detects and measures antimito-
chondrial antibodies in the blood circulation. Their
presence indicates various AUTOIMMUNE DISORDERS,
notably PRIMARY BILIARY CIRRHOSISandPRIMARY SCLE-248 The Immune System and Allergies