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Medications are but one part of the plan in the ongoing management of chronic pain. Advances in pain medications over the past 100 years have contributed to a better quality of life and a longer life. In fact, during that time, life expectation in males has increased from 60 to 79 years and, for females, to 83 years. There are benefits and disadvantages, however, when you consider taking these substances.

These medications act at different sites in your body. They include:

1. the peripheral pain receptors,
2. the nerve conduction,
3. the nerve synapse,
4. the dorsal column of your spinal cord; and
5. in the brain.

To reach these focal points in your nervous system, these drugs must be absorbed so that they can be delivered into your bloodstream. Medical scientists keep coming up with numerous options so as to get the best outcome for each patient. These options include:

1. through the skin (patches),
2. inhalation (nasal sprays),
3. submucosal (under the tongue),
4. orally (absorbed in the stomach and small intestine),
5. rectally (suppositories), or
6. by injection.

To be effective in your body, these medications must be absorbed into the blood. The route of entry can affect the amount of the chemicals that is absorbed and also the rate. In managing chronic pain, your doctor prefers to have steady absorption and a steady breakdown of the pain medications. We wish to avoid injections as they hurt and they provide only short acting relief. We prefer a steady level of medications and favour using controlled release drugs. Short-acting drugs, such as Endone, are avoided. The rate of absorption is affected by:

1. genes
2. enzymes
3. entry site
4. circulation
5. liver function
6. stomach contents
7. medication interactions.

So, when your doctor and you decide on a new medication, it is important that you recall all the medications that you are taking.

Once in your body, these medications are metabolised or broken down by the liver, the kidney, the bowel or the lungs. The doctor must have an excellent understanding of the processes in your body which affect the rate of breakdown of these materials. Aging and disease are two factors that can alter this reaction.

The advantages in the use of these medications would include:

1. They have the capacity to reduce pain.
2. They are available.
3. They are safe, provided the dose is correct.
4. Most can be taken by the patient at home.
5. They allow you to cope with everyday life.

Disadvantages include:

1. They do not cure chronic pain.
2. There are side effects.
3. They can affect your mood, behaviour and motivation.
4. There are withdrawal symptoms.
5. There are interactions with other drugs.
6. There is a risk of tolerance, dependence and addiction in a small number of people.
7. They are expensive.
8. They can affect your driving, particularly in the first two weeks.

Tolerance is a word that you should understand. It is a pharmacological effect in which the dose of the medication must be continually increased to gain the desired effect. For example, a patient is commenced on Oxycontin but, because the pain is not relieved, the dose is continuously increased.

Dependency occurs when a patient is using longterm medications, and that patient develops tolerance associated with negative symptoms of withdrawal which develop when the medication is suddenly ceased.

Drug addiction is a condition which is a disease of the nervous system. It is neurobiological disorder with origins that are genetic, psycho-social and environmental. It is characterised by the continuous use of a medication, despite its harmful effects. For example, there is an impaired control in the use of the drug and this is impulsive behaviour. There is a craving for the medication for non-treatment reasons.

The medications used in pain management target different sites in your nervous system. Medical science has increasingly begun to understand the different molecules in your body that facilitate or inhibit pain signals in your nervous system. These are called neurotransmitters. In the brain, the descending pathways are affected by noradrenaline, serotonin, dopamine, histamine and vasopressin. In the dorsal horn of your spinal cord the molecules are acetylcholine, gaba aminobutyric acid and opioid peptides. In the nerve fibres, there are Substance P and glutamate, to mention a few.

So our medical scientists have developed an effective range of medications that can target these molecules at each of the sites - the brain and descending pathways, the dorsal horn neurones in your spinal cord and along the sites in the peripheral nerves. These are examples:

• Analgesics ... Paracetamol
• Anti-inflammatory ... Ibuprofen
• Anti-depressants ... Amitriptyline
• Anti-epileptics ... Gabapentin
• Local anaesthetics ... Buprenorphine
• Opioids ... Morphine
• Alternatives ... Glucosamine

These powerful drugs have been developed to dampen down the pain signal as it travels through the nervous system.

Over recent years, a very accurate process has been developed for understanding the effect of each of these medications in your body.

All the international results from published trials over the past one hundred years have been brought together in the Cochrane Library, which is now online. It provides us with accurate information about the effect of each of these medications on a large group of pain patients. This has given us a new unit called "The numbers needed to treat".

This is the average number of patients a doctor would need to treat with the medication to get a 30-50% reduction in pain in just one patient. Ideally then, we would want a medication that is effective in every patient and this would give us a value of 1. If the value is 4, it means that for every forty patients treated, only ten get a 30-50% reduction in their pain.

Therefore, there is a League of Tables put out from Oxford:

• Tricyclic anti-depressives ... 2
• Valproate ... 2.1
• Carbamazepine/Lamotragine ... 2.3
• Opioids ... 2.5
• Tramadol ... 3.5
• Gabapentin/Pregabalin ... 4
• Mexiletine ... 4.5
• N.M.D.A. Antagonist ... 4.6
• Anti-depressives (SSRI) ... 6.5

Your doctor well understands that you might have reservations about commencing new pain medication. While in the average patient these drugs are safe, there are regular surprises because of the different genes and enzymes that you have in your body. There are surprises because patients do not always tell their doctors the range of medications that they are taking.

Even then, in the short term, there can be some unsettling effects from the drugs that will settle over a few days. During this time it is important that you remember that you should not drive until your body accommodates to the new substance. If there are unsettling complications, ring your doctor before you give up the medications.