Figures obtained by the Sunday Tribune show that the number of overdoses involving cocaine last year was double the figure for the entire 1990s.

In total, 292 people have died as a result of drug overdoses in the 24 months up to the end of 2005, new figures compiled by the Health Service Executive (HSE) show.

While historically the greatest single cause of drug-related deaths has been heroin and methadone . . . or either of these in conjunction with other drugs . . . it is the rate of increase in cocaine-related deaths that stands out among the new figures.

From 1991 until the end of the decade, there were just five deaths in which cocaine was a factor. In 2005 alone, this figure stood at 10 such deaths. That came at the end of a gradual upward trend, with 27 fatal drug overdoses since 2000 in which cocaine was a factor.

The new data is directly in line with parallel evidence suggesting that cocaine consumption may ultimately outstrip that of other drugs such as heroin.

Significantly, cocaine-related prosecutions have now eclipsed those for heroin, according to the garda annual report for 2005, the latest available.

Dr Des Corrigan, from Trinity College Dublin's School of Pharmacy, described the trend in relation to fatal overdoses as "worrying", but said that it did not seem surprising given the increase in the consumption of cocaine.

Corrigan said that contrary to the view held by many recreational drug users, cocaine is not a 'safe drug'. "Cocaine has the capacity to kill in the way it affects the heart. For some people, they cannot cope with it and the heart packs up, " he told the Sunday Tribune.

Among the risks associated with cocaine overdose is the occurrence of a process called vasoconstriction, in which the blood vessels narrow and the flow of blood is slowed, with potentially fatal consequences.

Corrigan warned that there is increased risk of internal damage when people consume alcohol and cocaine at the same time. Cocaethylene is formed in the body when cocaine and alcohol are taken simultaneously.

The substance does not occur naturally in coca leaves but has similar euphoric properties to cocaine, and is longer-lasting in its effects. Some studies suggest that it is more toxic than cocaine itself, particularly to the heart.

The TCD expert says, however, that the new figures should not be taken to suggest that cocaine alone is responsible for the deaths in which it is listed as being a factor. "These figures are crude in themselves, insofar as they point to overdoses in which cocaine is a factor. This may not necessarily mean that it was cocaine alone which was responsible for the person's death. It is the case that the number of overdoses in which cocaine is a factor is still much less than heroin or related opiates".

Corrigan warned that prolonged cocaine use can cause unseen damage. "In the long term, it makes the heart work harder. Quite like any muscle when you exercise it, it enlarges.

This does not make it more efficient. Far from it in fact, it actually makes it much less efficient.

By using cocaine, one is potentially storing up significant cardiovascular problems into the future."

A significant number of highprofile drug-related fatalities have occurred in recent years, among them the deaths of 13year-old Cavan girl Jamie Maughan; well-known criminal Declan Curran; and 15-year-old Carlow student James Ryan.

Maughan's death was ecstasyrelated. Her body was discovered in an estate in Cavan town in July 2004 and sparked a garda investigation leading to the conviction of a 23-year-old man for statutory rape.

Declan Curran died in Cloverhill jail in November 2004 after his arrest for suspected armed robbery. At his inquest, it emerged that he had taken a cocktail of drugs. James Ryan's death, following a cocaine overdose in September 2005, led to calls by the priest who celebrated the teenager's funeral mass to expel from local communities the dealers who "exploit children for drugs. We need to be vigilant against those people who want to use and exploit others, " said Fr Tom Little, parish priest of Askea.

"These people need to know they are not welcome in our community when all they bring is death and misery."

Research published last year indicates that drug-related deaths are no longer a Dublinbased issue alone. While the rate of such fatalities has decreased in the capital in recent times, the rate has grown outside of Dublin from four in 1994 to 35 in 2002.

The study by the Health Research Board (HRB) was based on information from coroners' records as well as other sources. One possible factor advanced to explain why the rate of deaths has dropped in Dublin was that more established treatment services and the provision of methadone maintenance to drug users in prison has become available.

The report noted, however, that while drug-treatment services have improved dramatically outside Dublin, they do not have the same level of development as those available in the capital.

The HRB report, Drug-related Death in Ireland 1990 to 2002, noted that more men than women died of drug overdoses in the period. Research shows that benzodiazepines, opiates (heroin and methadone) and alcohol are by far the most common substances implicated in drug-related deaths. Drugs such as cannabis, anti-depressants and stimulants (ecstasy and cocaine) are less commonly implicated. Multi-drug use, or polysubstance use, was also associated with deaths among drug users, while injecting drug use was associated with infection and subsequent death.

Studies between 1998 and 2001, drawn upon in the HRB report, show that drug task force areas such as Ballymun and Ballyfermot had the higher rates of opiate-related deaths for the reporting period, approximately 16 times the rate experienced in areas of Dublin not designated as task force areas.

The analysis presented in the report is based on data reported to the General Mortality Register (GMR) and on studies that extracted data from the coroners' records, the Central Treatment List and the Aids surveillance system.

While the figures available . . .

as Corrigan points out . . . are somewhat crude, the HRB's Drug Misuse Research Division (DMRD) is currently undertaking a major study of the link between specific drugs and deaths arising from overdose, based on a forensic analysis of coroners' records. It is hoped that this will form the basis for the most up-to-date and accurate data on the fatalities associated with use of specific drugs when used alone and when taken in association with other drugs.

This particular HRB research will not be complete until 2008.

It is only then that the full extent of cocaine's deadly influence will fully emerge.