Pills, Potions and Poisons: how drugs work
Trevor Stone & Gail Darlington Oxford University Press, 384pp, £18.99
ISBN 0198504039
Who at some time has not wondered what those tiny pills prescribed by a doctor actually do to us? Very few, I suspect. We simply take them to make us feel better. Sceptics of modern medicine may avoid the GP and, instead, visit a herbalist or homeopath under the delusion that "natural" products are somehow gentler on the body, but believe drugs (man-made or derived from natural products) work because the body itself is driven by a series of chemical reactions, any interference with which alters the balance.
Trevor Stone is a neuropharmacologist, and the best parts of this study relate to ailments of the nervous system: Parkinson's, Alzheimer's, epilepsy and depression. These disorders arise through changes in brain chemistry, for which semi-corrective measures can be effected using artificial mimics of the faulty chemicals. Similar kinds of mimics can also alter a more normal consciousness. It is no coincidence, then, that many symptoms of schizophrenia resemble those induced voluntarily by hallucinatory drugs such as LSD.
That a drug such as cannabis possesses chemical components that lead to prolific dampening of pain responses will surprise no one. Trevor Stone and Gail Darlington inform us that cannabis is in clinical use in many countries, including the US. The difficulties of sensible drugs legislation become self-evident when one begins to understand more about the crossover in chemical activity of drugs used clinically and those used recreationally, legally or otherwise. The voyeuristic chapter on love potions, Viagra and the aphrodisiac potential of other chemical entities is fascinating; but the Viagra story serves as a cautionary lesson in the priorities of drugs companies and the way in which they furtively divorce themselves from medical intervention in order to indulge their affairs with the newer models of lifestyle and recreation.
More than 40 per cent of all deaths worldwide are the result of infectious diseases, including malaria, tuberculosis and, increasingly, Aids. And yet less than 1 per cent of the 1,223 new chemical entities produced between 1975 and 1997 were destined for tropi-cal communicable disease - globalisation is not a term applicable to the drugs business. But then, each new drug costs an estimated $500m to develop - and, given that 67 per cent of all pharmaceutical purchases are made in Europe and North America, with Africa and south-east Asia combining to account for around 6 per cent, it could be said that the industry is wise to its market.
Developing new drugs is hugely expensive. Before a drug receives a licence, an enormous amount is spent on research and development to clear the regulatory hurdles that seek to ensure against dangerous side effects (everyone remembers the thalidomide catastrophe).
Side effects emerge from those drugs designed to tweak the actions of our own chemical composition. This is because molecules that serve as drug targets in one part of the body fulfil different tasks elsewhere. Penile erection, for example, was an irritating side effect of a drug called Sildenafil, used in trials against heart disease. It was through clever marketing that this side effect stimulated the pharmacological success story we know as Viagra. The problem, however, is that drugs are unable to distinguish the context in which they find their target. Until more subtle means of delivery are perfected, pharmacological intervention will remain akin to extinguishing a house fire by submerging an entire town in anti-incendiary foam.
Most diseases of the developing world are caused by infectious microbes, which differ genetically from humans and are abundant with "target" molecules that we do not carry. These provide opportunities to develop selective toxins, free from side effects. So while drugs against infectious agents may yield lower profits than, say, Viagra, this should be offset by substantially lower development costs. Tragically, such subtleties are lost on the marketing executives who hold a disproportionate influence in dictating drug development policy. And so the development of drugs against diseases of the third world remains static.
While Pills, Potions and Poisons touches on socio-economic realities associated with drug development, this is not the role it aims to fulfil. Instead, it is a sort of National Formulary for Beginners and, as such, serves as an excellent introduction to the biological effects of drugs.
Michael Barrett is a lecturer at the Institute of Biomedical and Life Sciences at Glasgow University
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