Cimetidine increases HDL-cholesterol, particularly in the HDL3 subfraction

Changes in high-density lipoprotein (HDL) cholesterol levels were monitored in five patients treated with cimetidine for gastrointestinal disturbances. A progressive rise of HDL cholesterolemia, statistically significant after four weeks of treatment and highly so after eight weeks (+ 25.4%) was noted. The composition of HDL2 varied insignificantly, whereas a marked rise of HDL3 cholesterol (+ 23.4%) and protein (+ 13.9%) was observed at the end of eight weeks. Cimetidine seems to act in a similar way as microsomal enzyme inducers, in spite of the described inhibition of specific pathways in drug metabolism; recent evidence shows that cytochrome P-450 turnover is delayed after cimetidine. Whatever the mechanism(s), H2 receptors may play a role in the cholesterol removal from tissues.