Plasma protein binding is the process a certain drug attaches itself to the proteins that are found within the blood plasma. A drug’s efficiency may be assessed by the how loosely or strongly it binds itself. For instance a loosely bound drug is said to be more effective as it can navigate through all the cell membranes. Protein binding is said to have a big command on the biological half life of any medicine. The part that is bound to the protein may act as a storage that supplies the drug slowly into the system. Under normal conditions, a drug may exist in two forms while it is still in the blood i.e. bound and unbound form. These forms are highly dependent on the drug’s attraction towards plasma protein. In most cases, one fraction of the drug may be bound while the other part may be unbound (Edmunds & Mayhew, 2004). Given that the unbound form of the drug is bio-transformed from the body, the other part of the drug may be liberated so as to maintain a steady balance. It is also important to note that while albumin is basic, the other drugs will primarily bind themselves to it. The other parts that have been discussed are both acid and neutral drugs. When the albumin becomes drenched, the other kinds of drugs that are both acidic and neutral will attach themselves to lipoproteins.
It has been shown through various researches that a patient taking Warfarin faces a higher chance of increased bleeding, if they decide to take a course of aspirin. This is because Warfarin is an anticoagulant that exhibits a therapeutic indication that is low (Edmunds & Mayhew, 2004).
Cytochrome P450
This is a cluster of enzymes that that can be found in the body particularly in the endoplasmic reticulum. The gene responsible for this cluster of enzymes has known to be in existence for the last three and a half billion years. High levels of this cluster of enzymes can be located in the liver and are also responsible for the transformation of many types of drugs including drugs that mitigate the effects of cancer into a less toxic form. This assists the body in excretion as issues can arise if the toxicity is let to exist. Endogenous compounds ingested orally through eating are metabolized and hence this is manifested through the high levels of concentration are also found in the small intestines. A number of mechanisms can modify the P450 system. These alterations exhibit themselves in the form of inhibitions and also differ from one individual to the other. Research into this group of enzymes is significant towards achieving full knowledge on how drugs are able to metabolize and interact with one another (Edmunds & Mayhew, 2004).
The Process of drug metabolism through P450 Enzymes
Drug oxidation requires molecular oxygen, NADPH and a flavoprotein. This is in addition to the drug substrate and the P450 enzyme itself. The overall reaction is addition of one atom to the oxygen atom while the other atom of oxygen forms water. However the mechanism involves complex catalytic cycles whereby the Cytochrome P450 reductase supplies one ore both of the electrons needed for the oxidation and subsequent restoration of the redox state of the Cytochrome P450 system. This process involves a cyclic oxidation reduction of the iron in conjunction with substrate binding and activation of molecular oxygen (Edmunds & Mayhew, 2004).
Cytochrome P450 with iron ions combines with the drug and then receives an electron from the reductase hence undergoing reduction from +3 to +2. This enables it to combine with molecular oxygen and then a proton. This is followed by another electron from NADPH P450 reductase. The latter complex now combines with another proton yielding to water and Ferric oxine drug complex which extracts a protein from the drug (Edmunds & Mayhew, 2004).
Reference
Edmunds, M. W. & Mayhew, M. S. (2004). Pharmacology for the primary care provider (2nd ed.). St. Louis, MO: Elsevier Mosby.