The Pharmaceutical Journal
Vol 269 No 7210 p196
10 August 2002

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Molluscan maze [more]
Drug peril in Asia [more]
Prescribers all [more]

Molluscan maze

I have been taken to task for misrepresenting some of the comments published in a sister scientific journal on the subject of deterring garden slugs and snails (PJ, 6 July, p34). If I have done less than justice to the item in question, I apologise. The feature that prompted my comments was intended to be light relief in an otherwise serious journal — a tongue-in-cheek discussion of an essentially frivolous nature. Humour is by its very nature an imprecise human characteristic, and not amenable to the factual analysis that should be applied to a research paper.
To continue the pursuit of the gardener’s enemy, it is surprising to see the press coverage stimulated by a brief communication published in Nature for 27 June by three agricultural research scientists from Hawaii. This paper reports preliminary trials demonstrating clearly that contact with solutions of caffeine effectively kills or repels slugs and snails when applied to the foliage or the growing medium of plants.
Since caffeine comes within the regulatory category known as “generally recognised as safe”, it has a massive advantage over its toxic alternatives. Cabbage leaves dipped in a caffeine solution and drip-dried were given to slugs over a four-day period. With drug concentrations of 0.01, 0.1, 0.5 and 2 per cent, the weight of cabbage leaf consumed by the molluscs was reduced by 9, 19, 29 and 39 per cent, respectively, compared with controls. Total leaf consumption when both treated and untreated leaves were offered was reduced by 24, 24, 14 and 28 per cent, respectively, showing that slugs can discriminate between treated and untreated leaves.
In vitro experiments with snails showed that their heart rate one hour after exposure to caffeine 0.01 per cent was raised, but after 0.1, 0.5 or 2 per cent it was reduced. After 24 hours cardiac irregularities were induced by caffeine concentrations of 0.1 per cent or more, and all snails exposed to 0.5 or 2 per cent were dead after 96 hours. With potted orchids in a greenhouse, 2 per cent caffeine was a more effective snail deterrent than the standard 0.195 per cent metaldehyde.
How caffeine kills molluscs is not known. It may release calcium from internal stores. Its high water solubility makes molluscs more susceptible to it than arthropods. Preliminary trials indicate that 2 per cent caffeine does not damage the foliage of Dracaena, Anthurium, palms or orchids, but may cause yellowing of ferns, bromeliads and lettuce. Mixing it with an appropriate polymer might ameliorate this effect and increase the water resistance of residues left by spraying.

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Drug peril in Asia

According to a report published in The Lancet for 1 June, there is a huge increase in production and use of illicit stimulants derived from amphetamine in many countries of east and south-east Asia. It was reported at a meeting of six Asian countries’ representatives in Beijing in May that efforts to reduce the production of opiates such as opium and diamorphine in that part of the world have been undermined by the increased availability of amphetamine-derived stimulants there.
According to the International Drug Control Programme of the United Nations, the fact that half the amphetamine abusers of the world live in east or south-east Asian countries presents a serious danger to health and the socio-economic fabric there. In Hong Kong and Indonesia abuse rates have risen markedly, while some increase has appeared in Thailand, Myanmar and the Philippines. Over the same period there has been a halt or decline in such abuse in Europe and America. Some 80 per cent of world amphetamine seizures have been made in east and south-east Asia.
Much of the illicit stimulant abuse in Asia involves intravenous injection, which increases the risk of diseases from blood-borne viruses such as HIV. Drugs are aggressively marketed in connection with competitive sports activities, and appeal particularly to the young and active. Much of the problem facing Asia stems from the fact that amphetamine derivatives are relatively easy to synthesise without complex equipment; indeed, it is claimed that they can be manufactured in a kitchen. Naturally, in the illicit market, there is no demand for quality control or even identity control, and this introduces yet another hazard for the user, which we are well aware of in the west.
Close co-operation between the countries affected is important, since if illicit production is subject to tight control in one of them, it will spread to adjacent states where the situation is looser.

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Prescribers all

I was intrigued to read in the BMJ for 29 June some comments by a fourth-year medical student on what have been called “prescribing rights.” She remarks that the politicians trying to put the health service on its feet have been arguing the pros and cons of transferring responsibility for prescribing beyond the doctors to embrace nurses, physiotherapists and pharmacists, without serious limit on the formulary available.
Discussions and sometimes heated exchanges between members of these various health professions at conferences have revealed,. she says, that prescribing rights are being extended too rapidly for safety and that medical students are at present offered inadequate time in their curriculum to learn the snags and pitfalls they will encounter in prescribing medicines.
Nurses, too, are in some confusion of mind when they are linked with pharmacists under the heading of supplementary prescribers. These two professions are visualised as working with doctors under the aegis of a clinical management plan. With the exception of Controlled Drugs and unlicensed medicines, supplementary prescribers would be entitled to use their informed choice, particularly over medicines for the treatment of chronic conditions such as diabetes and asthma. Moreover, a category of “independent prescribers” would be permitted to select prescription-only medicines for minor injuries and ailments or for health promotion and palliative care.
It has recently been remarked in an editorial contribution to The Lancet that perhaps nurses are being manipulated in an attempt by politicians to fill the gap created by a scarcity of doctors. The editorial comments that nurses, if thus used as supplementary prescribers, would need to add to their study programme basic and clinical pharmacology in some detail, together with general actions of drugs, pharmacokinetics and pharmacodynamics, not to mention develop the ability to weigh up evidence derived from clinical trials from time to time.
When you consider how little time is available in the nursing curriculum to devote to such topics, and how little too is allotted to it in the course of general medical training, you must feel doubts over prescribing ability as it exists at present.
It is a relief to note that no one, so far as I am aware, has recently expressed doubt over the capability of a modern pharmacist to take informed responsibility for vetting or issuing prescriptions. So far as our education in the nature and effects of drugs, their interactions and their adverse capabilities is concerned, we are far in advance of any other profession concerned with health care. Possibly we are too modest over this, and ought to make our voice heard more frequently.

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