PHARMACOLOGY

PHARMACOLOGY Pharmacology comes from the word root `pharmac' meaning medicine, and -logy, the suffix to study. Pharmacology deals with the chemical nature of medications and their effects on the human body. In the medical environment medications are usually referred to as drugs. Names of Drugs - Drugs are categorised by their function. If they are used to treat inflammation they are called antiinflammatories, if they are used to control high blood pressure, they are called antihypertensives, if they are used to fight bacterial infections they are called antibiotics. These are group names. Within each group, drugs are divided up according to their generic names. The generic name is the name that distinguishes the individual drug. However drugs have more than one name and they are usually sold under a trade name. This is the name given to them by the company that sells them. More than one company can sell the same drug and so although a drug only has one generic name, it can have many different trade names. A parallel to the way drugs names are divided can be seen in the way species are labelled. Pharmacology Page 1 of 7 It works in a similar way with drugs. Take some common pain relievers (analgesics) Panamax, Tylenol, Panadol and Dymadon are trade names of the one drug, paracetamol. They are sold by three different companies and have different packaging. The tablets may have a different shape but each of these drugs contains exactly the same active ingredient, 5OOmg of paracetamol. The same applies for aspirin. The only difference is the way in which the names are written. Generic names are not owned and do not need to be written with a capital. Trade names are registered and, like a person's name, must be written with a capital. Routes of administration Drugs can be administered to a patient in variety of ways. This varies depending on what type of drug it is, how quickly it produces an effect in the body, what type of side effects it has, and whether the patient is conscious or not. The route is usually described using the prefix `per', meaning 'through'. Most routes have corresponding abbreviations. Term Per oral Inhaled Sublingual Topical Pharmacology Meaning Through the mouth Breathed into the lungs Under the tongue On the skin Abbreviations PO, O SL TOP. Types of medication Tablets, syrups, powders Sprays or powders Certain tablets Lotions, powders, creams Page 2 of 7 Intramuscular Intravenous (injection) Per vagina Per rectum Drug Actions Side effects Into the muscle (usually IM, IMI an injection) Into the vein (usually an IV, IVI injection) Into the vagina PV Into the rectum PR Solutions for injection Solutions specifically for injection Pessaries, douches Suppositories, enemas Not all affects of drugs are positive. Many drugs have side effects and although the drug may be effective in one part of the body, it can cause problems in another area. For example, aspirin relieves pain but it can cause irritation of the gastric mucous membrane, and also can be a trigger for asthma. People who are sensitive to these side effects should avoid using aspirin. Contraindications Drugs are contraindicated (cautioned against) if it could cause undesirable or dangerous effects. For example, aspirin is contraindicated for people with gastric ulcers or asthma. Cumulation' Some drugs are stored in the body tissue for long periods of time. If the patient takes too high a dose for too long, the drug can accumulate in the body and cause toxic effects. For this reason, some drugs require the patient to have regular blood tests to check the level of the drug in their system. If the level is too high, the dose of the medication is adjusted. For example, digoxin is a common drug used to treat cardiac arrhythmias. It works by slowing and strengthening the heartbeat. However, if too much digoxin accumulates in the body the heart could become too slow and the patient could die. Tolerance As the body becomes accustomed to the effects of a drug, larger doses of the drug are needed to achieve the desired effect, for example drugs of addiction such as pethidine and morphine. Common types of drugs You will see from the following table that most of these medications work to stop something (hence the prefix anti-, Type of drug Antihistamine Antipyretic Analgesic Antiarrhythmic Antifungal Antibiotic Pharmacology Action Works against allergies Works to decrease temperature (pyr/o means fire or heat) Works to stop pain Works to stop abnormal heart beats Works to overcome fungal infestations Works to overcome bacterial infections Page 3 of 7 Diuretic Vaccine Antidepressant Anti-inflammatory agent Activity l Works to increase the amount of fluid filtered by the kidneys Works to protect the body from infectious diseases Works to overcome depressive illness Works to suppress inflammation in soft tissue What would be the most appropriate type of drug for each of following patients? Patient Disorder A B C D E F G Suffers from arthritis Suffers from fluid retention Has cardiac arrhythmias Has chronic depression Has a high temperature Has myalgia Has a bacterial infection Which drug should the patient be treated with? Types of drug antibiotic antipyretic antidepressant antiarrhythmic analgesic diuretic ant-inflammatory Dangerous Drugs All medications are potentially poisonous substances. Medications fall into two basic categories: 1. 2. Prescription medication - these are drugs that can only be dispensed only with a medical prescription written by a registered doctor, for example, antibiotics. Over-the-counter medication - these are drugs that can be purchased without a script, for example, aspirin. A medical practice will have a moderate supply of prescription medication on the premises. While these drugs can be an incentive for theft, prescription pads are also targeted. Never leave prescription pads lying in view of patients and encourage doctors to keep these pads in locked cupboards or drawers. The Poisons Act of 1966 describes the Australian laws regarding the storage and handling of all medications. The two schedules that apply specifically to medical practices are Schedules 4 and 8. As a medical office worker you will have some degree of contact with these medications. Although the doctor and nurses will be responsible for administering the medications to patients you may be responsible for checking and recording stock numbers, ensuring valid use-by dates and ordering new supplies. Pharmacology Page 4 of 7 Medications are potentially lethal substances and the misuse or theft of these medications is a crime punishable by jail. It is essential that you follow the laws and procedures associated with these drugs at all times. Schedule 4 - restricted substances These are medications that are for sale only on prescription. Schedule 4 medications include mildly addictive drugs such as those used to treat sleeping disorders, as well as non-addictive substances including as hormones, antidepressants and antiinflammatories. These medications must be securely stored and if they lost or stolen the incident must be reported to the police and the Pharmaceutical Services Branch. Schedule 8 - drugs of addiction Schedule 8 medications include highly addictive drugs such as morphine, pethidine and cocaine. Unauthorised possession of these drugs is illegal. These medications should be kept in a separate, locked cupboard that is securely attached to the wall or floor. Doctors are primarily responsible for these medications and often carry them in a locked bag. It is law that these medications be recorded in a drug register that is kept on the premises. This register should show all transactions involving the drugs; the amount of stock received, the date the medication was administered, who received it, what dose was given, and how much, if any, was discarded. All entries should be made in ink, signed and dated. Any mistakes should be explained in a footnote, initialled, and dated. Any loss or theft of these medications must be immediately reported to the police and to the Pharmaceutical Services Branch. Consumer Product Information (CPI) Consumer Product Information is the written information that accompanies a medication and tells the consumer about the drug: what it is, when and how it should be taken and possible side effects. Pharmaceutical Benefits Scheme (PBS) The Pharmaceutical Benefits Scheme is provided by the Commonwealth Government. PBS subsidies drugs so that although they can cost hundreds of dollars, the public can purchase them for much less. PBS Safety Net is a threshold where, after a specified maximum amount is paid per year, medication will be cheaper of free for the rest of that year. MIMS Trade names change frequently and both trade and generic names can be long and difficult to spell. If you are in any doubt you should look the name up in MIMS. MIMS is a manual that describes all the current drugs along with product information. Most doctors subscribe to MIMS and receive a new edition four times a year. The index has a listing of most current drug group, generic and trade names. There is also an EMIMS available Pharmacology Page 5 of 7 Abbreviations: ac bd (bid) cc HI IM IV K L NBM mane mg Na nocte NSAID po pr pv PC pp prn qd qid q4h q8h SC stat tds (tid) Pharmacology before meals twice daily with meals hypodermic injection intramuscular intravenous potassium litre nil by mouth morning milligram sodium night Nonsteroidal anti-inflammatory drug by mouth (per oral) per rectum per vagina after meals after meals as needed every day four times daily fourth hourly eighth hourly subcutaneous straight away three times daily Page 6 of 7 General terms: Anaphylaxis Abnormal reaction to a particular antigen, which is mediated by ige and which causes either local or widespread symptoms. Severe reaction of body to an allergen i.e. Medication Very small single celled organisms, surrounded by a cell membrane and cell wall - responsible for many of the infections for which antibiotics are used Any factor in a patient's condition that makes it unwise to pursue a certain line of treatment Abnormal reaction of the immune system to an antigen (igm or igg). Only occurs on second or subsequent exposures to particular antigens. (Usually inherited) The body's response of injury, infection or irritation Altered reaction of the body to one drug when another is taken at the same time A medicine that gives temporary relief from the symptoms of a disease but do not actually cure the disease (often used in the treatment of cancer or other terminal illnesses) A term applied to the administration of drugs or other substances by any route other than via the gastrointestinal tract A chemically inert substance given in place of a drug A reaction or consequence of medication or therapy that is additional to the desired effect Applied to skin or membrane Infective agents which are very small and unable to grow and, multiply unless, they invade the cell of another organism. Very common. To date, only a few antibiotics exist which are effective against them Bacteria Contraindications Hypersensitivity Inflammation Interaction Palliative Parenteral Placebo Side effect Topical Virus Pharmacology Page 7 of 7