Drug Eruption and Interactions - PHARMACEUTICAL REVIEW

Drugs that are the most common cause of TEN are:
allopurinol, ampicillin, amoxicillin, carbamazepine, NSAIDs,
phenobarbital, pentamidine, phenytoin (diphenylhydantoin),
pyrazolones, and sulfonamides.
Urticaria
Urticaria induced by drugs is, after exanthems, the second
most common type of drug reaction. Urticaria, or hives, is a
vascular reaction of the skin characterized by pruritic,
erythematous wheals. These welts – or wheals – caused by
localized edema, can vary in size from one millimeter in
diameter to large palm-sized swellings, favor the covered
areas (trunk, buttocks, chest), and are, more often than not,
generalized. Urticaria usually develops within 36 hours following
the administration of the responsible drug. Individual
lesions rarely persist for more than 24 hours.
Urticaria may be the only symptom of drug sensitivity,
or it may be a concomitant or followed by the manifestations
of serum sickness. Urticaria may be accompanied by
angioedema of the lips or eyelids. It may, on rare occasions,
progress to anaphylactoid reactions or to anaphylaxis.
The following are the most common causes of druginduced
urticaria: antibiotics, notably penicillin (more commonly
following parenteral administration than by ingestion),
barbiturates, captopril, levamisole, NSAIDs, quinine,
rifampin, sulfonamides, thiopental, and vancomycin.
DESCRIPTION OF THE 34 MOST COMMON REACTION PATTERNS 651
Vasculitis
Drug-induced cutaneous necrotizing vasculitis, a
clinicopathologic process characterized by inflammation and
necrosis of blood vessels, often presents with a variety of
small, palpable purpuric lesions most frequently distributed
over the lower extremities: urticaria-like lesions, small ulcerations,
and occasional hemorrhagic vesicles and pustules.
The basic process involves an immunologically mediated
response to antigens that result in vessel wall damage.
Beginning as small macules and papules, they ultimately
eventuate into purpuric lesions and, in the more severe
cases, into hemorrhagic blisters and frank ulcerations. A
polymorphonuclear infiltrate and fibrinoid changes in the
small dermal vessels characterize the vasculitic reaction.
Drugs that are commonly associated with vasculitis are:
ACE inhibitors, amiodarone, ampicillin, cimetidine,
coumadin, furosemide, hydantoins, hydralazine, NSAIDs,
pyrazolons, quinidine, sulfonamides, thiazides, and
thiouracils.
Xerostomia
Xerostomia is a dryness of the oral cavity that makes speaking,
chewing and swallowing difficult.
Resulting from a partial or complete absence of saliva production,
xerostomia can be caused by a variety of
medications.