<prompt> Megaloblastic anaemia may be caused by all of the following exceptPhenytoinMethotrexatePyrimethamineAmoxicillin  <response>: Phenytoin decreases folate absorption increases its excretion causing megaloblastic anaemia.Methotrexate is folate antagonist Pyrimethamine in high doses causes megaloblastic anaemia,especially in those with marginal folate stores.Reference :Tripathi essentials of medical pharmacology 7th edition 