Friday, 26 August 2016

pain paracetamol placebo

I'm an aspirin man myself [prev]. If I feel a headache coming on, which happens about once in two years, I pop a single Disprin ("soluble aspirin, the sort doctors prefer") and that will frequently head the headache off before I start weeping. therefore know nothing about chronic pain except what I see, hear and read about. The other sort of supermarket-available analgesic is paracetamol aka acetaminophen marketed as Tylenol (USA) Panadol (RoW) or Calpol (kids who like the added sweetener) And 100 other names in niche markets.  Unlike aspirin, paracetamol has no anti-inflammatory action; indeed its mode of action at all at all is a bit of a mystery. Nevertheless it is on the WHO list of essential medicines for a basic health care war chest.

In September 1982, when I was living in Boston, 7 USA people died after taking Tylenol capsules which had been deliberately adulterated with cyanide. There was a huge nationwide flap and all Tylenol packets in the country were taken off the shelves by MacNeil Consumer Healthcare, a subsidiary of Johnson & Johnson  aka J&J. Within a couple of months, the product was back on the shelves in tamper-proof triple packaging which is much harder for arthritic people to access.  Nevertheless, long-time consumer loyalty saw Tylenol's market share bounce back to almost pre-1982 levels. It wasn't the sort of event that would make folk change from aspirin though. Oh yes, and don't give paracetamol to your cat no matter how much she asks; cats lack the enzyme glucuronyl transferase, which breaks down the drug, and are likely to die from asphyxia because their blood can no longer carry oxygen. It's a bit like collie dogs and their adverse reaction to ivermectin.

Actually, don't bother to give paracetamol to anyone! Because a recent Cochrane analysis on several hundred people shows that it is no better than placebo at reducing subjective lower-back pain. The Cochrane Index are the Go To people for unbiased, authoritative advice about the efficacy and safety of medicines and medical devices. Cochrane has featured before on The Blob. If it's no good for lower-back pain, it is unlikely to be good for arthritis or headache or whatever-is-annoying-yourself. If one of your family secretly replaces the J&Js with M&Ms in the same bottle, you won't notice the difference. Then again, M&Ms are probably more expensive gram for gram than paracetamol, which costs 1c/US per pill in the developing world.

Then again then again, is paracetamol really as safe as it's made out to be? The trouble with legacy meds is that they have been on the market for so long that they have never been through the rigorous approval process required by the FDA for new medicines. They are generally recognised and safe and effective GRASE. Although, as we saw recently with hand-wash, the FDA will sometimes go after a seemingly innocuous omnipresent product.

We know from the essay "How not to commit suicide" by Art Kleiner in Co-evolution Quarterly [bloboprev] that overdosing paracetamol is a particularly grim way to off yourself.  Unlike cats, we have the enzymes used to process paracetamol and one of the break-down products N-acetyl-p-benzoquinoneimine NAPQI destroys the liver. So when you wake up from your suicide attempt, surrounded by your anxious loved ones, feeling like giving life another go, you find that you have sustained fatal liver damage . . . and have about five days left. That's deliberate o/d, and no amount of legislation is going to stop someone with reasonable resolve from acquiring a sufficient dose. Some effort is made to reduce the likelihood of accidental overdose / toxicity: notably by restricting the amount you can buy in one go. In Ireland this is 12 x 500mg in supermarkets and 24 x 500mg in pharmacies; it's slightly higher elsewhere. The recommended maximum dose is 3g/day, so you'll have to go to Lidl every other day for chronic pain relief. 10g/day puts you in the range of a toxic dose (YMMV), so there isn't much wriggle-room. These simple interventions in the free market have significantly lowered hospital admissions for overdose.

That's the blunt trauma end of adverse effects. What about chronic use for chronic pain, how does that stack up? Quoting from the Cochrane Blog previous cited: "paracetamol is associated with increased mortality, cardiovascular adverse events (fatal or non-fatal myocardial infarction, stroke, or fatal coronary heart disease), gastrointestinal adverse events (ulcers and complications such as upper gastrointestinal haemorrhage), and renal impairment".  You should really make the effort get yourself 'informed-consented' about the actual risks of these 'adverse events' compared to several decades sucking up the pain like some stoic philosopher in a toga.

But will someone please bring to market that placebo that works as well as paracetamol and leaves your liver alone? Placebo works! A lot of research has shown this: Injected placebos are better than oral placebos. Huge placebos are better than tiny ones. Red placebos are particular effective. This is one aspect of the righteous onslaught against homeopathy by the likes of Simon Singh and Ben Goldacre. They insist on a standard showing that homeopathy is better than placebo, because that's the gold standard in scientific case-control studies . . . and then don't offer placebo as an acceptable option on medical prescriptions. So the demonstrable positive effect of placebo on health and well-being is effectively driven from the market and multinational megapharm moves in to fill the void.

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