The Mechanism of Action of Pharmacology - Assignment Example

PHARMACOLOGY ASSIGNMENT . PHARMACOLOGY ASSIGNMENT Q1) briefly describe the mechanism of action of the sulfonamides. themechanism why they are selectively toxic to microorganisms. Is the principle of selective toxicity still valid today, why? Or Why not? Sulfonamides are antibacterial. They target the bacterial metabolic pathway as competitive inhibitors of the enzyme dihydropteroate synthetase or DHPS. DHPS activity helps in the synthesis of folate or folic acid. Folate is essential for the cells to make nucleic acids such as DNA or RNA. (MacLeod, 1943) When the DNA molecules cannot be built, the bacterial cells are not able to divide. Thus the effect of sulfonamides is bacteriostatic rather than bactericidal i.e. they help in preventing the growth of bacteria cells rather than killing the cells. Sulfonamides are used for the treatment of bacterial pneumonia, urinary infections and protozoa infections. Sulfonamides drugs are not harmful for the human cells. This is because the human body does not synthesize folic acid but folic acid is a dietary requirement for us .(MacLeod, 1943)This action of sulfonamides illustrate the principal of selective toxicity as the difference between cells of mammals and bacteria is exploited in order to make the drug harmful for bacteria but not for mammals. Q2) There is a considerable effort to diagnose and treat hypertension. Why is it important to treat hypertension aggressively? State the mechanism of action of any three classes of antihypertensive agents. Hypertension or high blood pressure needs to be controlled aggressively. When a patient suffers from hypertension for a long period of time, there is a high probability that he may suffer from stroke, heart attack or even kidney damage. Mild hypertension that is when blood pressure is less than 95 millimeter mercury diastolic should be treated if there is any damage to kidney or heart or blood vessels ; however blood pressure greater than 95 millimeters mercury diastolic should be treated urgently irrespective of any damage or not. Mechanism of action of 3 kinds of anti hypertensive agents – 1) Diuretics Diuretics increase the amount of salt and water being excreted by the kidneys. This decreases blood volume and also lowers the resistance of blood vessels thus leading to a decrease in blood pressure. (Sunil Nadar, 2009) 2) Vasodilators One example of the above drug is hydralazine. Vasodilators reduce blood pressure by direct relaxation of arterioles. 3) Nifedipine or calcium channel blocker This agent reduces the amount of calcium in cells of vascular smooth muscle. The decrease in the amount of calcium causes the relaxation of arterioles and thus reduces the blood pressure (Sunil Nadar, 2009) Q3) Describe the disadvantages and advantages of using antibiotics in combination. The advantages of using antibiotics in combination are following – 1) They can be used to treat severe infections in which the exact microorganism responsible is not known and the physician cannot wait for laboratory results due to severity of the infection. 2) When the infection is caused by 2 or more different bacteria and one antibiotic will not eliminate all the bacteria responsible for the infection. 3) Combination antibiotics are helpful in treatment of tuberculosis as the emergence of resistant tubercle bacilli is a hazard. In order to decrease the chances of bacteria becoming resistant to a single drug a combination of drugs is used. 4)In some infections a single drug may not be able to cure the disease but the combination of 2 drugs can cure the infection .e.g. – penicillin and amino glycoside are used against a bacteria called enterococci. Both of them together can cure the infection but each one alone cannot. The disadvantages of using antibiotics in combination are – 1) It leads to increased drug cost for the patient. 2) It increases the chances of toxicity. Toxicity caused by combination of drugs also causes difficulty in recognizing the drug responsible for the toxicity. 3) It also increases the resistance of bacteria to the antibiotics. 4) Combination drugs reduce normal bacteria population and thus remove their inhibiting effect on dangerous bacteria which may lead to the emergence of a super infection Q4) Oral contraceptive has had a major impact on society. Describe the mechanism of action of three different types of hormonal contraceptives Mechanism of action of 3 different types of hormonal contraceptives – 1) Estrogens- Progestin Combinations Estrogen prohibits the release of GNRH from the hypothalamus. This prevents the stimulation of pituitary to release FSH and LH. In the absence of FSH and LH, the follicles do not mature and thus it leads to inhibition of ovulation. (John Guillebaud, 2009) Progesterone makes the mucus secretion thick which throughout the whole menstrual cycle. This thick mucus is not conducive for sperm migration and thus prevents the sperm from reaching the egg for fertilization. 2) Progestin only Pills Progestin only pills inhibit the release of GNRH and thus lead to delay in ovulation. (John Guillebaud, 2009)The primary way in which they inhibit fertilization is by altering the endocervical secretions to a scant and thick fluid which is not optimal for the migration of sperms. 3) Ormeloxifene pills Ormeloxifene is a selective estroegn receptive modulator or SERM. Its effect is estrogenic in body parts like bones but anti-estrogenic in uterus and breasts. It causes the line of uterus to build slowly but speeds up the transportation of any fertilized egg to the uterus. The combination of these 2 effects leads an environment in which even if fertilization occurs, implantation will not take place. (John Guillebaud, 2009) Q5) Describe the rational use of over-the-counter vitamins. Why are fat soluble vitamins more toxic than water soluble vitamins? Uses of over the counter vitamins – 1) Fulfils inadequate intake Many people may be taking inadequate vitamins due to reasons such as poverty, geography, and food habits, eccentric, idiosyncratic or restrictive diet. These people usually suffer from lack of intake of a particular type of vitamin.OTC vitamins can be helpful to these persons in order to fulfill the bodily needs of vitamin intake. 2) Disturbances in Absorption Some people may be taking adequate amount of diet but may suffer from problems in vitamin intake due to diarrhea, liver disease or alteration of intestinal bacteria due to taking of antibiotics over a long period of time. These people need OTC vitamins which can be easily absorbed directly in the blood flow. 3) Increased requirements During certain periods of life such as pregnancy, lactation, excessive hard work or growth spurt the body requirement for vitamins increases. However the intake of food may remain the same. The gap can be bridged with the help of OTC vitamin pills. Excessive vitamin intake can be dangerous for the body. However fat soluble vitamins like Vitamin A, D and E can result in accumulation in body fact where they may cause severe toxic side effects. However water soluble vitamins are comparably less toxic because they are rapidly removed through the body urine. Q6) Describe the benefit of the following agents and their mechanism of action on athletic performance; erythropoietin, anabolic steroids, and amphetamine Amphetamines Amphetamines produce increase in alertness and give the athlete a feeling of power. They are powerful psychomotor stimulants. They increase the speed of the athlete as well his endurance leading to an overall increase in sporting performance. These drugs when given in moderate doses produce a 2 to 3 % increase in performance which at the level of Olympic performance can be the difference between a gold medal and the last position. Anabolic Steroids’ Anabolic steroids are compounds which reduce androgenic effects but maintain anabolic effects. They are used by athletes to increase muscle mass and strength. They also enhance physical appearance and are used in weightlifting and body building. Anabolic steroids give a more muscular appearance to the athletes. However it is not conclusive whether they increase strength and performance. They also produce roid rage or excessive aggressive behavior which is beneficial in sports like football. Erythropoietin Erythropoietin leads to an increase in the number of red blood cells in the body above the normal produce. When the number of red blood cells are increased, the oxygen carrying capacity of the body is also increased this leads to greater endurance and increased performance by the athlete. Q7) List 10 over-the-counter drugs you would take with you on a long weekend to the cottage. Give a one sentence rationale for each choice. 10 OTC drugs which I will take to a weekend in cottage are – 1) Ibuprofen – Ibuprofen is a drug which can be primarily used for pain and inflammation but can also be effective relive headache, earache, menstrual cramps and reduces fever. 2) Acetaminophen – It is also a pain reliever like Ibuprofen but it has the additional advantage of not irritating the stomach like Ibuprofen. Can be combined with Ibuprofen in case of a serious injury to reduce pain. 3) Diphenhydramine – It is primarily for drainage due to respiratory infections and nasal allergies. It also caused drowsiness and can be used in case of insomnia in the cottage. 4) Loperamide – It is the most effective instrument against intestinal cramping or diarrhea which can be fatal during a camping trip. 5) Pseudoephedrine should be taken to relieve any congestion of the respiratory tract due to infection or allergy. There are high chances of allergy in the cottage. 6) Meclizine should be taken in case someone suffers from nausea, vomiting or motion sickness during the trip. 7) Ranitidine is a drug which stops the production of stomach acid and thus can be effective if someone suffers from heartburn, ulcers etc. 8) Hydrocortisone cream is a steroid cream which is useful to treat itchy rashes. These rashes can occur due to some allergy in the forest. 9) Bacitracin Ointment should be taken to prevent skin infection in case any insect bite or sting takes place. 10) Clotrimazole should be taken to help reduce any female yeast infections, jock itch or ringworm. Q8) how do chemicals initiate the cancer process? Describe three approaches to the chemotherapy of cancer. Use examples as necessary. Cancer is a 3 step process which includes initiation, promotion and progression. Most of the cancers causing chemicals induce the first step in the cancer process which is initiation. Initiation means changes to the genetic code or the DNA which causes the triggering of cancer or abnormal reproduction of cells. (Roland T. Skeel, 2011)Any agent which induces cancer in cells is called as carcinogens. Some of the commonly known carcinogens are arsenic and its compounds, asbestos, Benzene, cadmium etc. some of the approaches of chemotherapy are – Isolated Infusion Approaches The approach works by delivering a very high dose of chemotherapy to the tumor site and does not cause major systematic changes in the body. This approach is helpful in treating localized or limited metastases but is ineffective against distributed metastases. Cancer of the liver and the lung has been treated with the help of this approach. Targeted Delivery Mechanism Targeted delivery approaches tries to increase the effect of chemotherapy for the tumor cells and reduces toxicity for other cells. These delivery vehicles interact with tumor associated antigens and thus have a higher affinity for tumor cells. Electro chemotherapy In this approach the first step is the injection of chemotherapeutic drug which is then followed by applying high voltage electric pulses on the tumor. The application of electric pulses allows the drugs to enter the membrane of cancer cells which leads to greater efficiency in treatment. It has been used for the treatment of cutaneous and subcutaneous tumors. Bibliography John Guillebaud, A. M. (2009). The Pill and Other Forms of Hormonal Contraception. London: Oxford University Press. MacLeod, C. M. (1943). Sulfonamides. New York: The Academy. Roland T. Skeel, S. N. (2011). Handbook of Cancer Chemotherapy. New York: Lippincott Williams & Wilkins. Sunil Nadar, G. L. (2009). Hypertension. London: Oxford University Press. . Read More