Which of the following anti-HIV drug should never be given as rechallenge once history of producing allergic reaction with drug is known?

Abacavir (ABC) This guanosine analogue is a potent ARV drug that acts after intracellular conversion to carbovir triphosphate. Resistance to ABC develops slowly, and it exhibits little cross resistance with other Nis. Its oral bioavailability is 80% and it is mainly eliminated by metabolism. The plasma half life is 1-1.5 hour, but intracellular half life of active metabolite is > 12 hours. Hypersensitivity reactions such as rashes, fever, flu-like symptoms are the major problems. Some fatalities have occurred when patients developing the reaction were given fuher doses of ABC. Avoidance of alcohol is advised. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:772