Solubility drug distribution affected

Since the volume of distribution is increased, the elimination half-life of lipid-soluble drugs is increased. This affects for example medium- and long-acting benzodiazepines as well as i.e. verapamil that can accumulate in the body. 

Ascites affects the volume of distribution of water-soluble drugs and may impair oral absorption of drugs, as the bowel may be oedematous. 

Aqueous solubility affects distribution because water-soluble drugs have difficulty crossing cell membranes and therefore tend to remain in the circulation. Consequently, water-soluble drugs are not well distributed throughout the body. They exist in large amounts in the plasma or tissue fluid and are rapidly cleared by the liver or kidney. In practice, such drugs have little therapeutic use. 

Thus, %F is defined as the area under the curve normalized for administered dose. Blood drug concentration is affected by the dynamics of dissolution, solubility, absorption, metabolism, distribution, and elimination. In addition to %F, other pharmacokinetic parameters are derived from the drug concentration versus time plots. These include the terms to describe the compound s absorption, distribution, metabolism and excretion, but they are dependent to some degree on the route of administration of the drug. For instance, if the drug is administered by the intravenous route it will undergo rapid distribution into the tissues, including those tissues that are responsible for its elimination. 

Fat content (e.g., obesity affects the distribution of drugs that are highly soluble in... 

As emphasized earlier, the concentration gradient of the drug in Eq. (1) refers to that of the unbound drug and its ionic distribution, which depends upon its acid-base properties. This can be modified by appropriate choice of excipients to ionize the drug by salt formation, thereby affecting the distribution of ionic versus nonionic species by acid-base equilibrium, using the Henderson-Hasselbach equation. All of the drug will eventually leave the depot and enter the body, but the rate may be reduced if membrane transport is limited by solubility of the neutral species within the membrane. 

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