Caffeine

Basic Info

Generally, it takes three to four hours to metabolise and clear half the caffeine in one's body. Children? metabolise caffeine quicker. Sensitivity to the effects of caffeine varies. Rather like alcohol, tolerance to the effects of caffeine varies with age and use.

Caffeine is readily absorbed and peak concentrations occur 30-60 minutes in young adults after eating or drinking it. High doses which slow metabolism down can remain in the brain between 9-15 hours.

Many factors affect caffeine metabolism

• Smoking
• Exercise - Moderate exercise increases the blood levels of caffeine and speeds up its metabolism
• Heredity - Caffeine metabolism is controlled by many genes and racial differences exist
• Pregnancy - Caffeine remains 2.5 - 7 times longer in the blood stream in late pregnancy. There are no placental barriers to caffeine so the fetus is exposed to its effects. In pre-term infants caffeine is cleared out of the blood only very slowly (half is removed over 65-103).
• Liver disease decrease caffeine metabolism.
• Drugs affecting caffeine metabolism
  Slow down metabolism
• Grapefruit Juice (not citrous fruits, this is a specific effect)
• Oral contraceptives
• Cimetidine
• Disulfiram
• Alcohol
• Idrocilamide
• Speed up metabolism and clearance
  
• Smoking/enzyme inducers
• Rifamprin