Cocaine misuse is extremely prevalent. One in 20 British adults reports having taken the drug in the past 12 months, giving us the highest rate of use in Europe.1 Problematic use of cocaine presents a major public health concern.
Cocaine is a natural alkaloid isolated from the leaves of the Erythroxylum coca shrub. It can be used via the nasal route or dissolved and then injected.
Crack cocaine is a more pure and volatile form produced by 'freebasing', which removes the hydrochloric acid from the salt.
Crack is a smokeable form of cocaine made into small lumps. It can also be injected.
Cocaine produces marked psycho-stimulant effects, by raising serotonin and adrenaline and depleting dopamine. It reduces fatigue and increases motor and sexual activity, as well as facilitating most cognitive functions. Cocaine is, in fact, closely related to methylphenidate, which is used therapeutically for ADHD.
Over-use can lead to extreme agitation, paranoia and hallucinations. The eventual 'come down' is characterised by fatigue, low mood and paranoia. Problem users will use frequently to avoid the 'come down'. Others prefer to use benzodiazepines or opiates to cover this period.
Most of the harmful effects of cocaine are related to injecting. The local anaesthetic and vasoconstrictor properties, as well as the high frequency of injection, make vein damage common.
This leads to early use of more dangerous injecting sites, such as the groin, with the subsequent increased risk of deep vein thrombosis and leg ulceration. Cocaine users also face the usual risks of parenteral drug misuse such as bacterial and blood-borne viral (BBV) infection.
Psychological dependence can develop easily. There is no typical physical withdrawal syndrome as seen with opiates but diarrhoea, vomiting, tremors and sweating can all occur.
Heavy use increases the likelihood of cardiovascular events and deaths, due to the potent vasoconstrictor properties.
Approximately one in four non-fatal MIs in persons under 45 years is attributable to frequent cocaine use.2
Although inhalation is a safer route than IV administration, sharing pipes can lead to BBV transmission, and inhaled crack cocaine can cause breathing difficulties and worsen asthma.
Some patients perform the Valsalva manoeuvre to enhance the effects of cocaine, leading to increased risk of pneumothorax and pneumomediastinum.
'Crack lung' is a rare but serious eosinophilic inflammatory condition, occurring one to 48 hours after smoking cocaine. It presents with acute dyspnoea, cough and haemoptysis and is treated with systemic corticosteroids.
Cocaine causes damage to the nasal mucosa due to the vasoconstrictive and anaesthetic effects. This can lead to chronic rhinitis, anosmia, nosebleeds and even septal perforation.3
Mental health problems such as depression and psychosis can occur and use in pregnancy can cause placental abruption, miscarriage or gastroschisis.
Despite numerous trials of psychotropics, including antidepressants, substitute prescribing continues to elude us. Vaccines are under trial but their widespread use is still years away.
The vaccine does not stop cravings but prevents any central effect if cocaine is used.
Antibodies bind to the cocaine molecule rendering it too large to cross the blood brain barrier.
It is likely that vaccination will be most effective in the highly motivated.4
Psychosocial intervention and harm reduction are the evidence-based therapeutic approaches available to users.
The Safer Injecting Handbook is invaluable (see resource) and the RCGP publication Guidance for working with Cocaine and Crack users in Primary Care is essential reading for all primary care clinicians.5
Screening for BBVs and accelerated hepatitis immunisation regimens should be offered. Do not await serological testing before immunisation.6 General checks such as BP measurement should not be forgotten, particularly for the older user. A brief mental health assessment is essential and advice on nutrition and dental care is important.
There is evidence for the effectiveness of non-pharmacological approaches. A voucher reward system has been researched in the US and has been considered by NICE. Vouchers to buy groceries or pay for leisure activities can be offered to people when tests show they are free of drugs, or if they agree to undergo tests for BBVs.
Less controversially, evidence from the largest ever UK trial has confirmed the effectiveness of psychological treatment. Among crack users, who were treated with either counselling or cognitive therapy, 57 per cent stopped and 8 per cent reduced their use.7
Referral to local drug services is vital. Hopefully, these services will be available, in addition to key working. A good relationship with the drug worker is the key therapeutic component for a patient using cocaine.8
- Dr Thomas is a GP in Swindon, Wiltshire
|Harm reduction advice|
1. The European Monitoring Centre for Drugs and Drug Addiction. Treatment of problem cocaine use, 2006.
2. Adnan I, Qureshi M, Suri F et al. Cocaine Use and the Likelihood of Non-fatal Myocardial Infarction and Stroke. Circulation 2001; 103: 502.
3. Gerada C. RCGP Guide to The Management of Substance Misuse in Primary Care. London, RCGP, 2005.
4. Martell BA, Orson FM, Poling J et al. Cocaine vaccine for the treatment of cocaine dependence in methadone-maintained patients: a randomised, double-blind, placebo-controlled efficacy trial. Arch Gen Psychiatry 2009; 66(10): 1116-23.
5. RCGP. Guidance for Working with Cocaine and Crack Users in Primary Care, 2004. www.smmgp.org.uk/download/guidance/guidance013.pdf
6. RCGP. Guidelines for Hepatitis A and B vaccination of drug users in Primary Care, 2005. www.smmgp.org.uk/download/guidance/guidance014.pdf
7. Marsden J,Eastwood B, Bradbury C et al. Effectiveness of community treatments for heroin and crack cocaine addiction in England: a prospective, in-treatment cohort study. Lancet 2009; 374: 1262-70.
8. National Treatment Agency for Substance Misuse. NECTOS National evaluation of crack cocaine treatment and outcome study. April 2007.www.nta.nhs.uk/publications/
9. Hepatitis C Trust. Drugs team give out cocaine straws. March 2009 www.hepctrust.org.uk/news/2009/March/Drugs+team+give+out+ cocaine+straws.htm
The Safer Injecting Handbook www.exchangesupplies.org