click below
click below
Normal Size Small Size show me how
Chemo therapy
Drugs and their effects
Question | Answer |
---|---|
What is chemotherapy? | the use of chemical agents against the living cell. Drugs used for the treatment of systemic or topical infections as they have selective toxicity for the invading pathogen without harming the host cells. Drugs used in management of various cancers. |
What are Antimicrobial agents? | synthetic or natural compounds which selectively suppress the growth or kill microorganisms in low doses. |
What are Antibiotics? | compounds obtained from one group of microorganisms which selectively suppress the growth or kill other microorganisms in low doses. All antibiotics are antimicrobial agents, but all antimicrobials are not antibiotics. |
What is a Bacteriostatic agent? | arrest the growth or replication of bacteria thus limiting the spread of infection. The host cell helps in eradicating the infection. Some bacteriostatic drugs have bactericidal action at higher concentrations e.g. Sulphonamides |
What is a Bactericidal agent? | kill or irreversibly damage the multiplying bacteria thus decreasing the viable bacteria |
what is narrow spectrum, with examples? | Effective against a limited range of bacteria. e.g Penicillin G, Streptomycin, Erythromycin. |
What is broad spectrum, with examples? | Effective against wide range of bacteria. e.g Tetracyclin, Chloramphenicol |
What is intermediate band with examples? | Wide extended spectrum. e.g Penicillin, newer Cephalosporins, Aminoglycosides. |
Drugs that inhibit cell wall synthesis? | Penicillins, Cephalosporin, Vancomycin |
Drugs that alter the cell membrane integrity? | Polymixins, Antifungal drugs: Fluconazole, Nystatin |
Drugs that inhibit ribosomal protein synthesis? | Bind to 30S subunit: Tetracyclines, Aminoglycosides Bind to 50S subunit: e.g. Chloramphenicol |
Drugs that inhibit synthesis of folates, purines/ pyrimidines: | Sulfonamides, trimethoprim, Ethambutol, pyrimethamine, |
Drugs that inhibit DNA gyrase? | Fluoroquinolones: Ciprofloxacin |
Drugs that interfere with DNA function? | Metronidazole, Rifampicin |
Drugs that inhibit either DNA / RNA polymerase: | Acyclovir, Anticancer drugs, Antiretroviral drugs |
Toxicity | AMA with low therapeutic index show higher degree of toxicity and should be used only as last alternative with constant clinical monitoring. |
Hypersensitivity reactions | All AMAs are capable of causing hypersensitivity reactions, which are unpredictable and unrelated to dose. They may range from rashes to anaphylactic reactions. |
Nutritional deficiencies | Vit. B complex and Vit. K are synthesized by the intestinal flora. The prolonged use of AMAs can alter this flora and produce vitamin deficiency. |
Natural Drug Resistance | Certain microorganisms have always been insensitive to certain AMA |
Acquired Drug resistance | Certain microorganisms have been initially sensitive to certain AMA but become insensitive over a period of time due to the frequent or irrational use of that particular antimicrobial agent |
Superinfections | Appearance of new infection,result of antimicrobial therapy. normal body flora inhibits growths of certain pathogenic organisms, preventing infection. If flora is inhibited , pathogenic organisms may predominate leading to new infection. |
Adverse effects | Depends on antibiotic, microorganism, patient. Common- diarrhea, disrupting flora. Fever,nausea,major allergic reactions,e.g photo-dermatitis or anaphylaxis. Impairing renal/hepatic function, result in plasma concentrations and drug accumulation toxicity. |
Chemoprophylaxis | It refers to the prior use of antimicrobial agents for controlling or suppressing the suspected infection thus preventing the clinical manifestations. |
What 3 conditions is chemophylaxis done? | Prophylaxis against specific organisms Prophylaxis in high risk situations Prevention of infection in general |
Prophylaxis against specific organisms (Chemoprophylaxis) | Highly satisfactory as specific drugs are used to prevent specific infection. e.g. Isoniazid alone or in combination with rifampicin for prophylaxis of TB in children and in HIV positive cases. |
Prophylaxis in high risk situations (Chemoprophylaxis) | Amoxicillin / Clindamycin may be prophylactically used before and after the dental extraction, tonsillectomy, endoscopies to prevent infection. |
Prevention of infection in general (Chemoprophylaxis) | This is highly unsatisfactory in most cases. e.g Giving AMA to mothers after delivery to prevent post-partum infections. It may be hazardous as infection may occur with resistant organisms. The chances of superinfections are also increased. |
Antimicrobial combination and its advantages | A combination of antimicrobial drugs should be used carefully as it may offer certain advantages. To achieve synergism To reduce the severity or incidence of adverse effects To prevent emergence of resistance To broaden the spectrum of AM action |
Antibacterial Drugs | Cephalosporins, Fluoroquinolones |
Antifungal drugs | Fluconazole, Nystatin |
Antiviral drugs | Acyclovir, Zidovudine |
Antiprotozoal drugs | Metronidazol, Chloroquine |
Anthelmintic drugs | Mebendazole, Diethylcarbamazine, Praziquantel |
Antimicrobial Resistance | AMA is no longer effective due to inappropriate use. Organisms develop drug tolerance, destroy the AMA, or stop entry into the cell. Due to mutation or gene transfer. |
How to minimize the development of drug resistance? | Administration of right dose for the right duration |