Tiêu đề Chemotherapeutic drugs 1.pptx ✅

Chemotherapeutic drugs
DISCOVERY AND DESIGN OF ANTIMICROBIAL AGENTS Antibiotic - traditionally referred to natural metabolic products of fungi, actinomycetes and bacteria that kill or inhibit the growth of microorganisms. Antibiotic production has been associated with soil microorganisms In the natural environment - provide a selective advantage for organisms in their competition for space and nutrients. Majority of antibacterial agents in clinical use today are derived from natural products of fermentation Most are then chemically modified (i.e. semi-synthetic) to improve their antibacterial or pharmacologic properties. Some agents are totally synthetic (e.g. sulphonamides, quinolones). Therefore, the term ‘antibacterial’ or ‘antimicrobial’ agent is often used in preference to ‘antibiotic’. Agents used against fungi, parasites, and viruses can also be included under antimicrobials, but the terms antifungals, antiprotozoans, anthelmintics, and antivirals are more often used.
The desirable features of ideal antimicrobial agents are: Antimicrobial properties selectivity for microbial rather than mammalian targets Cidal activity (antibacterial & antifungal agents) Slow emergence of resistance Narrow spectrum of activity (depends on drug usage. Narrow-spectrum drugs cause less disturbance to normal flora and may contribute less to emergence of antibiotic resistance, whereas broad-spectrum compounds are more useful for empiric therapy and treatment of polymicrobial infections. CSF, cerebrospinal fluid) Pharmacologic activities non-toxic to the host Long plasma half life Good tissue distribution including CSF Low plasma – protein binding oral and parenteral dosing forms No interference with other drugs
The discovery of new antimicrobial agents used to be entirely a matter of chance. Pharmaceutical companies undertook massive screening programmes searching for new soil microorganisms that produced antibiotic activity. Understanding of the mechanisms of action of existing antimicrobials, the processes have become rationalized, searching either for new natural products by target-site-directed screening synthesizing molecules predicted to interact with a microbial target Genomic approaches to the identification of novel targets Knowledge of the crystal structure of the key enzymes involved in viral replication such as protease, reverse transcriptase and helicase leads to the design of new drugs.