Hypersensitivity reactions
Dermatologic ADRs are difficult to be distinguished as a side effect of
or an allergic reaction to these drugs or a flare of the underlying
dermatological disease (87,88). The most common manifestation is mild
pruritic MPEs within initial 4 weeks of treatment
(87). High association with AGEP [OR:
39 (8-191)] was described (89). Cases
of DRESS (90,91), pustular DRESS
(92), erythema multiforme
(93), bullous erythema
(94), SJS/TEN (95-97), photoallergic
dermatitis (98), and occupational
contact dermatitis (99) have been
reported.
PTs are reported to be useful for the diagnosis of NIHRs (93,95,100),
confirming a T-cell mediated mechanism. However, in a series of 14
patients with ADRs due to chloroquine/hydroxychloroquine, skin tests
(STs) were negative in all cases (87). DPT is useful in non-severe
cutaneous ADRs in order to differentiate allergic reactions from
dermatological adverse effects since only 30% of the patients reporting
cutaneous ADRs reveal a positive DPT
(87). Successful desensitization
protocols of hydroxychloroquine in MPE were reported (101-104).
Recently, a 5-hour desensitization protocol for non-immediate urticaria
was successfully administered (105).
Two cases of IHR were reported (106,107)
and one was confirmed by SPTs (106), however there are no available data
for in vitro diagnosis. A hydroxychloroquine desensitization
procedure that enables the turning of positive SPTs into negative was
published (106). In a case of
anaphylaxis a 7 day-desensitization procedure was successfully performed
with premedication (107).