RBC precursors of megaloblastic anemia
abnormally large and have nuclei that appear much less mature than would be expected from the development of the cytoplasm (nuclear-cytoplasmic asynchrony).
Drugs causing Megaloblastic Anemia:
P–>Phenytoin (Fenytoin–>Folate deficiency)
L–>Liver Disease (speaking of the MC drug Alcohol, think of Liver as well)
The MC drug is Ethanol. This is easy to remember. You cannot buy drugs like Methotrexate, AZT or Phenytoin OTC, but you can cause yourself liver disease and megaloblastic anemia using the ethanol=alcohol, because it is so easy to buy it. Alcohol is not OTC drug, alcohol is OTS drug, which means On The Shelf drug. Everybody can buy alcohol, and that is why ethanol is the MCC of Megaloblastic Anemia and many other disease. The second MC killer in US right after cigarettes smoking.
Image source: wikipedia