You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
fixed drug eruption ( fde ) is characterized by the development of one or more annular or oval erythematous plaques , more commonly on the lips or genitalia .
the hip , lower back and proximal extremities are also common sites for the initial lesion of an fde , which may be solitary .
these lesions typically resolve spontaneously after discontinuation of the causative drug but leave a residual hyperpigmentation at the reaction site(s ) . repeated or continued exposure to the suspected drug might cause the development of new lesions along with enhancement of the older hyperpigmented lesions .
cd8 t cells retained in the lesions serving as an immunological memory may get activated on re - challenge .
persistent expression of intercellular adhesion molecule 1by an abnormal subpopulation of keratinocytes facilitates the adhesion of lymphocytes that express lymphocyte - associated antigen1 , which in turn liberates lymphokines , causing damage to epidermal cell layer .
oxidative stress parameters such as reduced glutathione , malondialdehyde , and inhibition of leukocyte migration have also been significantly noted in fde .
drugs such as ibuprofen , sulfonamides , naproxen , and tetracyclines are the most common among more than 100 drugs that have been implicated to cause fdes .
older , as well as newer generation antihistamines , have also been reported to cause fdes .
although rare , a few cases of fde with cetirizine , levocetirizine . have also been reported .
there are also reports of fde in the same patient due to levocetirizine as well as cetirizine or other piperazine derivatives , but such reactions appeared after intentional re - challenge or patchtesting in patients who presented with an fde with levocetirizine / cetirizine .
we present a case of fde in a patient with a history of fde with cetirizine , who was inadvertently given levocetirizine .
a 49-year - old male patient , a known case of scabies with prior treatment with topical permethrin and oral cetirizine , presented at the department of community family medicine , aiims , bhopal .
he was prescribed tablet vermact ( ivermectin ) 12 mg stat , tablet rantac ( ranitidine ) 150 mg bd ( twice a day ) , and tablet levorid ( levocetirizine ) 5 mg od ( once a day ) for 3 days .
about 1h after taking levocetirizine , the patient experienced several bullae formations with generalized itching and multiple erythematous macules on the left lower leg [ figure 1a ] , right sole [ figure 1b ] , chest , penis , and middle finger right hand .
the patient has a history of similar lesions at same sites with cetirizine 1month before current presentation .
cetirizine also had been prescribed for scabies in a government hospital before presentation at aiims , bhopal .
levocetirizine was stopped and tablet dazit ( desloratidine ) 5 mg od , along with clob ( clobetasol propionate ) cream , for topical application twice a day on erupted areas of the skin , was prescribed to treat the reaction .
the lesions resolved with a faint lingering hyper - pigmentation after 7 days of withdrawal of levocetirizine along with the above treatment . de - challenge was thus satisfactory
. fixed drug eruption with levocetirizine : reddish erythematous macular patches on right sole ( a ) and left lower leg ( b ) ( column width ) the adverse drug reaction ( adr ) has been reported to the pharmacovigilance programme of india through in - house adr monitoring centre .
( worldwide unique number at uppsala monitoring center : 201538822 ) . using the world health organization causality assessment criteria ,
causality was determined as certain with levocetirizine by the causality assessment committee of the concerned adr monitoring centre .
levocetirizine is generally considered as a safe and effective drug for different allergic diseases such as allergic rhinitis and chronic urticaria .
paradoxically , there have been several reports of hypersensitivity reactions , including fdes , due to levocetirizine , cetirizine and other antihistamines of the piperazine group . however , while there are reports of fde with levocetirizine and cetirizine in the same patient , these patients were deliberately re - challenged by oral route or by patch - testing with levocetirizine or cetirizine . on the other hand , in our patient levocetirizine
was used therapeutically in a patient with a history of cetirizine - induced fde and led to a similar reaction .
levocetirizine is the r - isomer of cetirizine dihydrochloride and has two times more affinity for the histamine h1 -receptor than cetirizine .
fdes usually appear as erythematous , pruritic macules , which may occur due to systemic exposure to a causative drug .
these lesions typically resolve spontaneously after discontinuation of causative drug but recur on re - administration of the causative agent .
fdes are cd8 + t cells mediated classical delayed - type hypersensitivity reactions . in the present case , the patient developed levocetirizine induced fde .
oral re - challenge test is the most reliable method for diagnosis of an fde .
however , since the lesions after levocetirizine reappeared on the same sites as those with a chemically similar drug , that is cetirizine , a diagnosis of levocetirizine induced fde can be made without re - challenge .
further , it is recommended that a patient with history of hypersensitivity to a certain antihistamine should be expected to cross - react with other antihistamines of the same chemical class .
antihistamines with least structural resemblance to the offending agent should be used in such a patient .
a fixed drug eruption ( fde ) is a cutaneous adverse drug reaction due to type iv or delayed cell - mediated hypersensitivity . 
 antihistamines , which antagonize the action of histamine during an allergic reaction by blocking the h1 histamine receptors , are used routinely for the treatment of various allergic disorders such as urticaria , eczemas , and also in itchy lesions of skin like scabies . 
 levocetirizine , an active ( r)-enantiomer of cetirizine , is a newer or second generation antihistamine , with more specific actions and fewer side effects , including cutaneous reactions . 
 fde due to levocetirizine as well as with cetirizine are rare . 
 we report a case of levocetirizine induced fde in a 49-year - old male patient with scabies . 
 the patient had a history of cetirizine induced fde in the past .