通过化增强的H+/Cl-由胺-尿素结合物共同运输

During the process of renal excretion, as the glomerular filtrate progresses to the distal convoluted tubule (DCT), drugs that are highly permeable, lipophilic, and nonionized undergo passive reabsorption from the tubular fluid into the surrounding peritubular capillaries. This reabsorption process restricts their elimination through the kidneys. However, the majority of drugs are either weak acids or weak bases, and their ionization level is dependent on pH. By altering the pH of urine, the...

Once the process of glomerular filtration is completed, blood carrying unfiltered drug molecules traverses through efferent arterioles and makes its way into the peritubular capillaries in the proximal tubule. A variety of carriers play a pivotal role in actively secreting drugs from these peritubular capillaries into the tubular fluid. The organic anion transporter transfers acidic drugs, against an electrochemical gradient, from the peritubular capillaries into the renal tubule cells and...

Phase II biotransformations are detoxification mechanisms that conjugate xenobiotics with endogenous substances, neutralizing their toxicity.
A key example involves the conjugation of cyanide ions, which impair cellular respiration and alter hemoglobin into non-oxygen-carrying cyanmethemoglobin. To neutralize this threat, a sulfur atom from thiosulphate is transferred to the cyanide ion, catalyzed by the enzyme rhodanese, resulting in an inactive compound called thiocyanate. The production of...

Conjugation, a key component of phase II biotransformation reactions, is a vital process in drug detoxification. It involves transferring endogenous substances like glucuronic acid, sulfate, and glycine to drugs or their metabolites formed in phase I reactions. These conjugation reactions, often catalyzed by specific enzymes, transform potentially harmful metabolites into inactive, water-soluble forms easily excreted in urine or bile. By enhancing polarity and eliminating pharmacological...

Pore transport and ion-pair formation are critical mechanisms for the absorption and distribution of drugs in the body.
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited  but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct...

Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).