You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Low apparent volume of distribution (aVd) indicates: and explain in detail?
Ans. A. Drug is not extensively distributed in organs and tissuesVolume of distribution (Vd ) is defined as ratio of the amount of drug in the body and the plasma concentration of drug (Cp)Vd = Total dose administered to patient/Cp Volume of distribution can be determined by various factors:A. More plasma protein binding restricts drug to plasma, hence there will be less distribution to extravascular space and tissues (least Vd ).B. Polar compounds have slightly more volume of distribution (Vd :0.2L/kg)C. More tissue binding capacity or more lipid solubility will make drug to cross most of the membranes, including blood-brain barrier making volume of distribution more.D. Sequestration of drugs in the particular tissue makes its volume of distribution even more than whole blood volume (e.g., Chloroquine has large volume of distribution as it gets sequestered in the liver)Water (0.6 L/kg)Lipid soluble molecules: e.g., EthanolExtracellular water (0.2L/kg)Water-soluble molecules: e.g., Gentamicin Polar compoundsBlood (0.08L/kg)Plasma (0.04L/kg)Strongly plasma protein-bound molecules and very large molecules: e.g., heparin