GI blood flow in Relation to Drug Absorption
Drugs may move away from the serosal side of the digestive tract by one or two mechanisms.
The digestive system provides a network of capillaries from the splanchnic circulation. It is possible that the drugs are picked up by the lymphatic vessels in the epithelium of the digestive system and transmitted through the lymphatic system, which distracts the abdominal region of the abdominal area into the thoracic duct. Any drug is absorbed by this device, which enters the systemic circulation directly and is not exposed to the first liver passage. Most of the drugs are predominantly absorbed by the capillary system with visceral circulation, although both the capillaries and the lymphatic system exist.
The reason for this seems to be the relative velocity of blood and lymph flow. The blood flow velocity in the visceral circulation is 1 - 1.5 l / min or 30% of the product of the heart. This can increase to 2 liters / minute after a meal. While the flow velocity of the lymph during the same area is only 1-2 ml / min, but can increase to 5-20 ml / min after a meal. Thus, the lymph flows in this area less than the blood flow by about 500-700 times. The relative velocity of the visceral blood flow provides the actual penetration conditions on the parietal side of the digestive tract epithelium and also ensures a high concentration gradient. These conditions increase the effective absorption into the blood stream more than the lymph.
Only a few drugs are absorbed by the lymph system. These drugs include drugs with high molecular weight that can not enter capillaries and dedicated molecules such as steroids.
Drugs may move away from the serosal side of the digestive tract by one or two mechanisms.
The digestive system provides a network of capillaries from the splanchnic circulation. It is possible that the drugs are picked up by the lymphatic vessels in the epithelium of the digestive system and transmitted through the lymphatic system, which distracts the abdominal region of the abdominal area into the thoracic duct. Any drug is absorbed by this device, which enters the systemic circulation directly and is not exposed to the first liver passage. Most of the drugs are predominantly absorbed by the capillary system with visceral circulation, although both the capillaries and the lymphatic system exist.
The reason for this seems to be the relative velocity of blood and lymph flow. The blood flow velocity in the visceral circulation is 1 - 1.5 l / min or 30% of the product of the heart. This can increase to 2 liters / minute after a meal. While the flow velocity of the lymph during the same area is only 1-2 ml / min, but can increase to 5-20 ml / min after a meal. Thus, the lymph flows in this area less than the blood flow by about 500-700 times. The relative velocity of the visceral blood flow provides the actual penetration conditions on the parietal side of the digestive tract epithelium and also ensures a high concentration gradient. These conditions increase the effective absorption into the blood stream more than the lymph.
Only a few drugs are absorbed by the lymph system. These drugs include drugs with high molecular weight that can not enter capillaries and dedicated molecules such as steroids.
