US hospitals object to changes in Genentech drug distribution

Upon entering the systemic circulation, drugs can distribute into the interstitial and intracellular fluid of various tissue cells. This distribution is facilitated by the binding of drugs to different cellular components within tissues, which may lead to drug accumulation in specific areas. Drugs bound to tissue components serve as reservoirs that release free drugs back into the system, prolonging the drug's overall action. However, this accumulation can also result in local toxicity.
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Drug distribution within the body is a dynamic process involving the movement of a drug in two directions across various compartments: from the bloodstream into tissues (tissue uptake) and from tissues back into the bloodstream (tissue release or redistribution). This process is passive and primarily driven by two variables: the concentration gradient between the bloodstream and the extravascular tissues and the drug's ability to cross the cell membrane.
Initially, the free drug in the...

Drug distribution in the pediatric population exhibits unique challenges and considerations due to the physiological differences between children, particularly neonates and infants, and adults. A crucial aspect of pediatric pharmacology is understanding how these differences impact the pharmacokinetics of various drugs, necessitating age-specific dosing strategies to ensure efficacy and safety.Neonates and infants have a higher total body water content, ~75%–90% of their body weight,...

Drugs predominantly attach to plasma proteins, with only a small percentage remaining unbound. The unbound portion can be calculated as one minus the bound fraction. Acidic drugs form large, inactive complexes by reversibly binding to plasma albumin, which prevents them from diffusing across biological barriers. These drug-protein complexes act as reservoirs for the drugs. As the concentration of unbound drugs decreases, these complexes quickly dissociate to release the free drug, maintaining...

Drug distribution in the human body is influenced by several factors, including plasma protein concentration, body composition, blood flow, tissue-protein concentration, and tissue fluid pH. Among these, changes in plasma protein concentration and body composition due to aging significantly affect how drugs are distributed within the body. Specifically, aging is associated with a decrease in albumin levels by about 10% and an increase in α1-acid glycoprotein levels. These alterations are...

The volume of distribution refers to the theoretical volume necessary to contain the entire amount of an administered drug at the same concentration observed in the blood plasma. The body's intracellular fluid compartment, which makes up two-thirds of the total body water, is contrasted with the extracellular fluid compartment—comprising plasma and interstitial fluid—that accounts for one-third. The volume of distribution can vary depending on the characteristics of the drug.