|Analgesic nephropathy (Photo credit: Wikipedia)|
Chronic use of over the counter pain killers have previously been cited as something to avoid if you have kidney disease. There is well established evidence that mixed analgesics have negative effects on kidney function.
So much so that a specific disorder chronic analgesic nephropathy has been described. It has been defined as the renal damage that occurs when two analgesics and caffeine or another drug is taken routinely over years. You may ask yourself who would take such medication on a chronic basis? However many people with chronic disease particularly painful conditions for which there is no definitive therapy such as chronic osteoarthritis or nerve damage take these drugs for relief of chronic pain. Problems occur with dependence induced because of ingredients such as caffiene codiene or barbiturates.
Drugs that have been implicated here include
in combination with,
- or barbiturates.
|A few weeks in Vietnam 310 (Photo credit: JaulaDeArdilla)|
The disease itself is slowly progressive over many years and is associated with findings of scarring of the kidney with shrinking of the cortex (the place where a lot of the work of filtration is done), and over time there is a chance of transformation to transitional cell cancer of the kidney ureter or bladder.
Some Points to take home about Analgesic Induced Kidney Disease.
- The use of CT-SCAN has recently been validated as a method of detecting analgesic nephropathy in patients with stage 3 and 4 CKD. The CT scan is done without contrast and hence is safe.
- Analgesic induced kidney disease is invariably caused by compound analgesic mixtures regardless of the presence or absence of phenacetin as one of the active ingredients. Phenacetin was once thought to be the primary cause of analgesic induced nephropathy, this has proven to be false as the disease can occur with any of the drugs listed above.
- Healthy individuals who occasional take the above drugs are not at risk of renal disease.
- Paracetamol is frequently prescribed instead of aspirin like compounds because of the known association of kidney disease with aspirin however paracetamol is also a cause of analgesic induced kidney disease although the risk is described as modest.
- Analgesics may cause acute renal failure. The renal failure however is not always reversible when the drug is withdrawn.
- Once kidney disease occurs continued use of the offending drug worsens the chances of recovery and increases the rate of progression to end stage.
- In patients with stage 3 to 4 CKD the dug of choice should be the drug with the least chance of producing acute renal failure and it should be used for as short a time as possible. hence short courses of paracetamol is indicated for pain.
- Despite the toxicity of the ingredients, it is the addictive nature of the habit forming co ingredients which creates the chronic dependence which can lead to ESRD.