- How are medicines made?
In the past, all medicines came from plants or animals. Although some important medicines still come from plants or animals (e.g. morphine), most medicines used today in the developed world are manufactured through chemical processes.
All new medicines must undergo thorough testing before being approved for use. Before a new medicine can be tried in humans it must undergo extensive testing in the laboratory, to assess its safety and biological activity. This 'pre-clinical' development stage may last as long as 3 or 4 years. Then clinical trials in human volunteers, determine if a medicine is safe and effective, at what doses it works best and what side effects it causes.
A typical clinical trial development programme
Stage
Number and type of patients
Typical duration
Purpose
Phase I
20-100 healthy volunteers
Up to 1 year
To ensure the medicine is safe and find the most suitable dose
Phase II
Up to several hundred patients
1-2 years
To assess effectiveness and look for side effects
Phase III
Several hundred to several thousand patients
2-4 years
To confirm effectiveness and monitor any side effects from long-term use
Each new medicine entering development is given a chemical name (e.g. lisinopril, used to treat high blood pressure). Occasionally, this chemical name is called something different in different countries (e.g. paracetamol and acetaminophen are the same). However, once a medicine has been licensed for use in patients by the medicines agency of a country, the manufacturer can sell the medicine under a brand or trade name (e.g. Zestril).
Patenting of a new medicine guarantees the manufacturer a 20-year period of protection, during which no other companies can legally make or sell the medicine. However, once this period has expired, other pharmaceutical companies can make the medicine. These ‘copycat’ medicines are called ‘generic’ medicines.
- How do medicines work?
In general, medicines work by:
· Replacing substances that are deficient or missing in the body,
· Altering the activity of cells, or
· Destroying infectious micro-organisms or abnormal cells
Replacing substances that are deficient or missing in the body
The body needs certain levels of proteins (or amino acids), vitamins and minerals in order to work normally. If these important substances are insufficient or lacking, this can lead to medical disorders. These are called ‘deficiency disorders’. Examples include: iron deficiency (anaemia), and vitamin C deficiency (scurvy).Deficiency disorders can also occur as a result of a lack of hormones in the body (hormone deficiencies). Common examples include: diabetes (insulin deficiency) and hypothyroidism (thyroid hormone deficiency). Deficiency disorders can be treated with medicines or hormones that replace or restore the levels of the missing substances, for example insulin injections for diabetics.
Altering the activity of cells
Cells are the basic ‘building blocks’ of the body. All human tissue is made up of groups of cells. Many medicines work by altering the activity of cells. For example, anti-inflammatory medicines such as ibuprofen and diclofenac block the action or stop the production of chemical substances (mediators) which are released by cells in response to tissue damage and which cause inflammation and pain. Medicines which interfere with the way cells work are used to treat a variety of conditions, such as blood clotting disorders (e.g. anti-coagulants), heart (e.g. calcium channel blockers) and kidney diseases.Some medicines work by attaching themselves (binding) to sites found on the surface of cells (receptors) and either increase or decrease the activity of the cell (e.g. medicines used in the treatment of epilepsy and Parkinson’s disease).
Destroying infectious microorganisms or abnormal cells
Infectious diseases occur when viruses, bacteria, protozoa or fungi invade the body. Antibiotics e.g. penicillin can destroy bacteria by killing them directly or by preventing them multiplying. Anti-fungals commonly used for infections of the skin and mouth (e.g. clotrimazole and miconazole) work by disrupting infected cells. Other medicines work by killing abnormal cells, for example some anti-cancer drugs directly target and kill harmful cancer cells.
- How quickly do medicines work?
The time it takes for a medicine to work varies from medicine to medicine. For example, glyceryl trinitrate, a medicine commonly used to treat chest pain associated with angina, is used as a tablet and, increasingly in the form of a spray, and provides almost immediate relief from the symptoms. In contrast, some medicines used to treat anxiety, nervous disorders and depression can have a delayed effect and, depending on the drug, days or even several weeks’ treatment may be required before a patient experiences real benefit.
For more information on the various methods of taking medicines, please read ' How to take your medicine '.
- How to take your medicine
By mouth (orally):
this is the most common way of taking medicines.
The medicine is swallowed and passes from the stomach or intestine into the bloodstream and is carried to all parts of the body. The speed at which this happens depends on several factors:- The form in which it is given (e.g. syrup or tablet)
- Whether it is taken with food, after food or on an empty stomach
- Its ability to pass into blood vessels
- How it reacts with the acidic conditions in the stomach and alkaline conditions of the upper intestine
- Whether it interacts with other medicines given orally
Also certain medications to treat angina and sickness are placed under the tongue or between the teeth and the cheek respectively. With these types of products where a quick effect is desirable, the medicine is absorbed rapidly into the bloodstream through the lining of the mouth.
By injection: medicines may be injected to produce an effect on the entire body. Medicines are often injected when people are unable to take medicines by mouth (or other routes into the body are inconvenient or inappropriate), when a very rapid effect is needed or for medicines that aren't absorbed well when given orally.
There are several ways of injecting medicines:
- Intravenous (IV): the medicine is injected directly into the bloodstream, usually via a vein near the surface of the body (e.g. in the hand). Medicines injected intravenously enter the bloodstream directly and reach their site of action almost immediately (e.g. anaesthetics).
- Subcutaneous (SC): the medicine is injected just beneath the skin. Medicines that are inactivated by the stomach acid or medicines that need to be absorbed slowly may be injected subcutaneously (e.g. insulin).
- Intramuscular (IM): the medicine is injected into muscle, usually the thigh, upper arm or the buttock. Intramuscular injections provide a very steady level of absorption and are used, for example, for antibiotics such as penicillin.
Injections are also sometimes used to deliver a medicine directly to the area that needs treatment e.g. steroid injections into joints.
Rectally: the lower end of the large intestine (rectum) that leads to the anus will absorb many medicines. The medicine passes through the cells lining the rectum and into the bloodstream. This method is useful for people who are unable to take medicines by mouth, such as those suffering from nausea and vomiting. Suppositories and enemas are given rectally.
Topically: medicines that are applied directly to the part of the body which is being treated, e.g. the skin, eyes, ears or nose are called topical medicines. Various types of topical preparations are available, including:
- creams
- ointments
- lotions
- pessaries
- suppositories
- ear, eye and nasal drops
- sticky patches, e.g. hormone patches and nicotine patches
This is a good way of taking medicines that require a long, slow release into the body.
By inhalation: medicines may be inhaled through the mouth or nose to produce a rapid effect on the lungs and airways (e.g. asthma inhalers and nebulized solutions for chronic airway disease). Some medicines which have an effect on the whole body (e.g. general anaesthetics) may also be inhaled. Migraine medicines and medicines used to relieve nasal congestion may also be given by a nasal spray, to provide rapid relief of symptoms.
- Tips on taking your medicine
Always read the instructions carefully
Always take your medicine as recommended. If in any doubt contact your doctor or pharmacist.
Measure your medicines carefully
(E.g. use a medicine spoon, or only inhale the recommended number of puffs). It is important to take only the recommended dose of your medicine, as too much can be harmful and too little might prevent the medicine from working properly.
For liquid medicines, remember to shake the bottle before measuring out the correct amount,as some liquid medicines may ‘settle’ at the bottom of the bottle.Take your medicine at the recommended intervals and recommended time
When your doctor says you should take your medicine 3 times a day space out the doses fairly evenly (e.g. in the morning, afternoon and before you go to bed).If your doctor tells you to take your medicine at a certain time of the day, follow this advice as it can be important with some blood pressure tablets and other medicines which work better at particular times of day.
Follow instructions
If your doctor specifies taking your medicine with or after food, it is important that you follow these instructions. Some medicines such as certain anti-inflammatory medications should be taken with, or after, food to avoid the possibility of stomach upsets. If you are advised to take your medicine on an empty stomach (as is commonly the case with antibiotics), it is probably because the medicine will be absorbed more quickly if the stomach is empty.
Don’t chew, crush or break tablets or capsule
Don’t chew, crush or break tablets or capsules unless your doctor has told you to do so. Some medicines have a special coating and will not work properly unless they are swallowed whole. If you are unable to take tablets or capsules ask your doctor or pharmacist if there is an alternative, which might be more suitable for you.Don’t stop taking your medicine
Don't stop taking your medicine or adjust the dose or change how often you take it without speaking to your doctor or pharmacist.Complete the course of your prescribed medicine
For example, if you have been prescribed antibiotics, you should make sure you complete the course, even if you feel better; if you don't, the bacteria causing the infection may not be completely destroyed and the infection could return. Many medicines need to be stopped slowly, with regular checks from a doctor to ensure there are no health problems.Furthermore, you should not stop taking your medicine even if you feel better, as your doctor may have prescribed it to prevent recurrences of your condition, e.g. migraine and asthma medicines. If you experience any side-effects or the medicine doesn't seem to be working as it should, contact your doctor or pharmacist as soon as possible. He or she may be able to prescribe/recommend a different but equally effective medicine.
Special patient groups
The following groups of people may need to be particularly careful when taking medicines:Children
It is very important that children are given a medicine which is right for them and that they receive a dose recommended for their age. Some medicines are not recommended for use in children and adult doses of medicines could be very dangerous if given to a child, as they may be much higher than the child needs. If a child has an allergy (e.g. to penicillin) be sure to remind the doctor.Children often have several different caregivers in a single day (e.g. parents, teachers, babysitter and grandparents). It is important that each caregiver understands how to give the child his or her medicine safely. A diary may be helpful to keep track of what medicine has been given and what time it was given at, as younger children will not always be able to tell if they have already received their medicine.
Elderly people
As we get older, our livers and kidneys become less efficient at breaking down and getting rid of medicines and this can result in medicines building up in the body. Because of this, elderly people may require lower doses of the medicine than the normal adult dosages. Elderly people are also more likely to be taking a number of medicines at the same time and therefore care must be taken in order to avoid potentially harmful interactions with other medicines. Your doctor or pharmacist will be able to advise on the importance of any potential interactions.Elderly people may also be more likely to forget whether they have taken their medicines and take a double dose. It is best to seek advice if this is a possibility.
There are several products available which may help to remind elderly people to take their medicines on time and keep track of what medicines they have taken. These include calendars which can be checked off, containers with sections for daily doses and bottle caps that beep when it is time to take a tablet. When people are taking several medicines, a medicine tray can be useful to help organise the medicines.
Pregnant or breastfeeding women
Expectant mothers rightly are concerned about the effects of any medicines they take can have on theirs and their baby’s well-being. While many medicines are safe to use during pregnancy, others are known to have harmful effects on the health of the baby or the mother. Medicines taken by a pregnant woman can cross the placenta and enter the baby’s bloodstream and may affect the baby’s development.Mixing medicines
Medicines can interact with each other and cause problems so if you are taking medicines you should always mention this to your doctor or pharmacist before taking any extra medicines.However, you can and should continue to take your prescribed medicine under the guidance of your doctor. Medicines may also have different effects at earlier and later stages of the pregnancy and your doctor may need to change your regular medicines during the course of your pregnancy. When purchasing medicines “over-the-counter” make sure that you seek the advice of your pharmacist about whether the medicine is right for you.
If you are (or think you may be) pregnant, planning to become pregnant, or if you are breastfeeding, you should consult your doctor before taking any medicines, even medicines available without a prescription
- Your medicine
Understanding your medicine
Understanding your medical condition and the role your medicine plays in your treatment will help you to get the most benefit from your prescription.You should make sure you fully understand your condition, and why and how to take your medicine. This will ensure your medicine works properly and will reduce the possibility of side-effects.
Medicines often come with a leaflet of instructions on how to take or use them and a list of what they contain. You should always read the label on the container or instruction leaflet before you start any course of treatment. Ask for a leaflet if you do not appear to have one.
It is important that you only take the recommended dose and know how long to take your medicine. If you are unclear on the details ask your doctor or pharmacist to explain this to you.
It is very important to remember that your medicine is prescribed for you - and you alone - and you should never share it or give it to someone else who says they have the same symptoms; this can be very dangerous, as your medicine may not be suitable for them.
Make sure you don't take a double dose by mistake, particularly when you top up your supplies as “repeats” or “refills” for longer-term treatments.
Remember that medicines are known by two names, the 'chemical' name (e.g. lisinopril) and the trade name (e.g. Zestril). Also some medicines, particularly older ones, may be available from different manufacturers and the tablets from each manufacturer may look different. In some countries e.g. in European countries, medicines from another country can be provided by pharmacists. So sometimes different packs of medicines can look different but actually contain the same active ingredient. If you are in any doubt, ask your pharmacist.
- Talk to your doctor
It is important that you are involved in any decisions about your treatment. Do not be afraid to ask questions and discuss any concerns you have. When you are prescribed a new medicine, you might want to ask your doctor or pharmacist some questions.
Some questions to ask your doctor or pharmacist when you are prescribed a new medicine
· What does this medicine do?
· How long will I need to use it?
· How and when should I take it?
· Should I avoid any other medicines, drinks, foods or activities when I am taking this medicine?
· What are the possible risks and side effects – and what should I do if they happen to me?You can help your doctor to prescribe the best treatment for you by discussing what is important to you about your medicines. For example, you might want the medicine which is the fastest acting, or which has the fewest side-effects or it may be really important to you that you only take your medicine once a day.
You should always tell your doctor or pharmacist if you are taking any other medicines (prescription and 'over-the-counter') including the contraceptive pill or vitamin and herbal and natural remedies/supplements. This is important because:
· Some medicines react with other medicines to produce unpleasant side-effects and may even be contra-indicated (totally unsuitable).
· Medicines can block the effects of other medicines and stop them working or may interact to make the effect of the medicine stronger.
· Different medicines may contain some of the same ingredients and taking more than one medicine at the same time may mean that you get too much of a particular ingredient.An important aspect of being involved in your treatment involves checking and recording your own health. A simple way to do this is by using a diary. It only takes a few minutes each day to fill out a diary, noting how you feel and describing any symptoms or adverse effects you experience. This can help you and your doctor to monitor your condition and see if you are getting the most out of your current treatment plan.
Finally, your doctor needs to know about any changes to your treatment plan and it is important that you are open and tell your doctor if you are not taking your medicine as he or she recommended.
- Storing your medicine
The label or instruction leaflet supplied with your medicine will provide instructions on how to store it properly. Some medicines should be stored in a refrigerator (eg. insulins and certain eye drops used for bacterial infections or glaucoma).
The cap should always be replaced on medicine bottles and child-proof caps should be locked on.
All medicines should be stored safely out of the reach of children.
You should always check the expiry date on medicines. If your medicine is out-of-date, return it to your pharmacist.If you have any unused medicines, you should return them to your pharmacist who will dispose of them for you. Do not simply throw them away
The label or instruction leaflet supplied with your medicine will provide instructions on how to store it properly. Some medicines should be stored in a refrigerator (eg. insulins and certain eye drops used for bacterial infections or glaucoma).The cap should always be replaced on medicine bottles and child-proof caps should be locked on.
All medicines should be stored safely out of the reach of children.
You should always check the expiry date on medicines. If your medicine is out-of-date, return it to your pharmacist.If you have any unused medicines, you should return them to your pharmacist who will dispose of them for you. Do not simply throw them away.
- Your pharmacist
Your pharmacist or hospital pharmacy will be able to give you advice on the use of the medicine(s) you have been prescribed, including how to take them and any likely side effects. Your pharmacist will also tell you if there are any other medicines you should avoid while you are taking your prescribed medicine.
Pharmacists are also qualified to give you advice on how to treat minor ailments and illnesses including coughs, colds, flu and sore throats, common skin and eye complaints and may suggest medicines that you can buy over-the-counter. If your pharmacist is unable to help you with your condition, he or she will suggest you go and see your doctor.
Many people, especially those who feel well but should take medicines e.g. for high blood pressure, do not take all their medicines or may even stop taking them altogether. Reasons for this may include:
· They are not exactly sure how to take their medicines
· They do not understand the importance of taking their medicine in managing their illness
· They have experienced side-effects
· ForgetfulnessPharmacists play an important role in helping people to get the most benefit from their medicine by explaining their illness and its treatment. Pharmacists can help by:
· Explaining how medicines work and the importance of taking them properly
· Giving advice and guidance to clarify or explain information on packs and in leaflets
· Advising on which over-the counter (OTC) are suitable to treat minor ailments for patients taking prescription medicines
· Advising people about common side-effects and what they mean
· Using large print on label
Encouraging people to use medicine diaries, calendars or medication charts and support to help with compliance such as dose reminders for tablets and devices to help with taking inhaled medicines, eye drops etc.
- Your prescription
The following information is commonly provided on a prescription but may vary from country to country:
Your full name and address
Doctor’s full name, address and telephone number
Date the prescription was issued
Doctor’s signature
Doctor’s identification / registration number (unique number given to all doctors)
Medicine name, dose, dosage form and amount
Directions for use
Refill or repeat prescription instructions
Doctors often use shortened instruction when issuing a prescription. It is important that you ask your doctor or pharmacist to explain any medical terms or abbreviations you do not understand.Examples of commonly used medical abbreviations
Medical Abbreviation Meaning ac
before meals
pc
after meals
po
by mouth
bd / bid
twice a day
tds / tid
three times a day
qds / qid
four times a day
mdu
as needed
prn
as necessary/when required
od
once daily
qd
every day
qqh
every four hours
mane
in the morning
nocté
at night
mitte
give
sig
dose/ frequency
Date of preparation: 21st January 2008
C14228
