Classification of drugs

The most popular approach to drug design by synthesis is to start with the pathology of the diseased state and determine the point where intervention is most likely to be effective (see Chapter 7). This enables the medicinal chemist to suggest possible lead compounds. These compounds are synthesized so that their pharmacological action may be evaluated. Once a suitably active lead is found, structural analogues of that lead are produced and screened in the hope that this procedure will eventually produce a compound that is suitable for clinical use. Obviously this approach is labour intensive and a successful outcome depends a great deal on luck. Various modifications to this approach have been introduced to reduce this element of luck (see Chapters 4-6). 

Drugs are classified in a number of different ways depending on where and how the drugs are being used. The methods of most interest to medicinal chemists are chemical structure and pharmacological action, which includes the site of action 

The term prodrug (see section 2.7.1 and 9.8) is often used for drugs whose active form is produced by enzyme or chemical action at or near to its site of action. However, it is emphasized that other classifications, such as the nature of the illness and the body system on which the drug acts (physiological classification), 

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Figure 15.5 Sammon map with SVM classification of drugs based on their volume of distribution (a) and plasma half-life (b) [95].

Deconinck, E Hancock, T Coomans, D., Massart, D. L, Vander Heyden, Y. Classification of drugs in absorption classes using the classification and regression trees (CART) methodology. 

FIG. 6 Classification of drug delivery sites in lipid bilayers. 

Before each chapter, a list of key terms or classifications of drugs or both is included to aid review. In addition, suggestions for effective study and review have been added afterward. 

Lennernas H and Abrahamsson B (2005) The Use of Biopharmaceutic Classification of Drugs in Drug Discovery and Development Current Status and Future Extension. J Pharm Pharmacol 57 pp 273-285. 

Lennernas H, Abrahamsson B (2005) The use of biopharmaceutic classification of drugs in drug discovery and development Current status and future extension. J Pharm Pharmacol 57 273-285. 

Volpe DA, Faustino PJ, Ciavarella AB, Asafu-Adjaye EB, Ellison CD, Yu LX, Hussain AS (2007) Classification of drug permeability with a Caco-2 cell mono-layer assay. Clin Res Reg Affairs 24 39 17. 

CysLTs) are proinflammatory molecules synthesized primarily by basophils, neutrophils, and mast cells and are potent mediators of airway inflammation and bronchoconstriction (77,78). There are two classifications of drugs in this category that can regulate the effects of CysLTs inhibitors of the 5-lipoxygenase enzyme, such as zileuton, and CysLT receptor antagonists, such as montelukast and zafirlukast. 

Prediction of bioavailability from molecular structure is quite difficult, since bioavailability depends on absorption and first-pass clearance [141]. By applying fuzzy adaptive least squares , Yoshida and Topliss generated a QSAR model using logD at pH 7.4 and 6.5 as input for physicochemical properties and the presence/absence of certain functional groups as structural input. They achieved a classification of drugs into one of four bioavailability categories with an overall accuracy of 60% [142]. 

Currently, however, the more or less universally accepted classification of drugs used for treating tachyarrhythmia is based on the characteristics of their effect on electrophysio-logical or biochemical processes in the myocardium. 

Antibiotics can be classified according to their effects on the biochemistry or molecular biology of pathogens. There are ribosomal inhibitors (macrolides), cell wall disrupters 0-lactams), DNA disturbers (fluoroquinolones), and metabolic poisons (trimethoprim-sulfamethoxazole). Antibiotics also can be classified according to whether they are static (inhibitory) or cidal (lethal). The classification of drugs as either static or cidal is based on laboratory assessment of the interaction of pathogen and antibiotic drug. 

Teratology Society, Public Affairs Committee (1994) FDA classification of drugs for teratogenic risk. Teratology 49 446 47. 

Table 7.3.1 Classification of drugs used in peptic ulcer. ...

The law focused new attention to the growing problem of abuse of prescription drugs. It gave responsibility for enforcement to the U.S. Attorney General, with help from the Department of Health, Education, and Welfare on determining the appropriate classification of drugs. A new agency... 

TABLE 14.1 U.S. DRUG ENFORCEMENT AGENCY CLASSIFICATION OF DRUGS... 

FIGURE 13.10 Classification of drugs approved by the U.S. FDA from January 2004 to June 200611... 

To provide a context for our discussion of Rx-to-OTC switches, we will describe briefly the classifications of drugs that must be limited to prescription use. Specifically, the following types of drugs must be sold for prescription use only (1) drugs not safe for use except under the supervision of a licensed practitioner because of toxicity or other potential for harmful effect, method of use, or the collateral measures necessary for use and (2) drugs limited to prescription under an approved NDA [87]. FDA may remove by regulation a drug subject to the premarket approval requirements from prescription status when such requirements are not necessary for the public health [88]. 

Gunther EC, Stone DJ, Gerwien RW, Bento P, Heyes MP. Prediction of clinical drug efficacy by classification of drug-induced genomic expression profiles in vitro. Proc Natl Acad Sci USA 2003 100 9608-9613. 

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