atches. Capsaicin cream comes in 2 strengths (0.025% and 0.075%). The lower strength can help the pain of arthritis and the stronger solution can help some neuropathic pains such as scar pain and that of postherpetic neuralgia. The problem with this cream is that it can burn and irritate before it works and more often than not it will stop working if its use is stopped.
Lidoderm patches can also be useful in scar pain and postherpetic neuralgia. These patches are impregnated with local anaesthetic. They do not make the skin greasy and stop working after they are removed so constant use may be needed.
NSAIDS are also available in creams and apart from being effective, cause almost negligible damage to the stomach and kidneys. They help approximately 1 in 3 people who use them regularly.
Patches containing the strong painkillers fentanyl and buprenorphine are also available and may help in both cancer and non-cancer pain unresponsive to weaker painkillers. Both are licensed for use in patients with chronic non-cancer pain.
Delivery of drugs to the body
Most people take drugs by mouth. Increasing numbers of people absorb drugs using patches. There are of course other ways of delivering drugs to people. These ways are used because not everyone can swallow drugs and even if they do, the dose required is higher than that achieved. Other routes include into muscles, directly into veins and under the skin, under the tongue, inhaled through the nose and lungs and also via the back passage.
The most effective way of delivering drugs, however, is by putting them directly into the nervous system as this where the drugs actually do most of their work. This is done by ‘tapping’ into the space around the spinal cord as already talked about in the section on low back pain and epidurals.
Tapping a little further leads to the subarachnoid (item 5 in the picture) or spinal space where the spinal cord and cerebrospinal fluid are. In both areas a catheter or hollow tube can be left and drugs infused into it. It has to be stressed that this is a highly specialised area of drug delivery and only the very basics can be explained without tremendous background detail being required. It is also used in very few patients with chronic non-cancer pain is has a greater place in the treatment of cancer pain.