Routine Drug Screen
Toxicology Overview / Directory
Purpose of the test
A routine drug screen is made up of the most common illicit drugs in the UK.
Opiates
Opiates are a class of drugs that are derived from the opium poppy, Papava somniferum, that is grown in Asia, especially in Afghanistan, Thailand and Laos. The resin from the poppy forms crude Opium, which used to be smoked but is now rare in the UK. A series of purification steps are used to extract the main alkaloid, Morphine, which is licensed as a narcotic analgesic, but may also be abused. As a recreational drug, this is more commonly found in the acetylated form diacetylmorphine, better known as heroin. There are a variety of other opiate drugs that are available either on prescription or over the counter, and others that are found as contaminants of street drugs. The most notable of these are Codeine and dihydrocodeine.
Amphetamines
Amphetamine is a primary amine that is a Central Nervous System stimulant licensed for use in the treatment of narcolepsy, or as a second line treatment for Attention Deficit Hyperactivity Disorder. However, its greatest use is as a recreational stimulant, and it has been used for years under the street name “speed”. There are also a variety of derivatives of amphetamine used as recreational drugs, the most notable being Methylenedioxymetamphetamine (ecstasy, MDMA) and metamphetamine (Ice or crystal Meth).
Methadone
Methadone is a synthetic narcotic analgesic, with painkilling properties similar to codeine. It acts on the same group of neuroreceptors as opiates, and is therefore classed as an opioid. It is licensed for use in the UK for severe pain, although its primary pharmaceutical use is in the treatment of opiate addiction.
Methadone is given to opiate users as a replacement for heroin, as it gives relief from withdrawal symptoms with reduced psychological effects and a more reliable oral effect. The dose is more regulated and the effects longer lasting, although methadone causes greater physical dependence than morphine and heroin.
Methadone is usually taken as a linctus, although other preparations are available, including for injection. There is a market for illicit methadone, as heroin users may not always want to or be able to take heroin. Methadone is therefore likely to be detected in clients on a methadone maintenance program and on first presentation to drug counselling services.
Cocaine
Cocaine is an alkaloid obtained from Erythroxylem coca, a plant found naturally in the Andes region of South America. It is licensed only for use as a local anaesthetic for otolaryngology, but its stimulant properties mean that it is used extensively as a recreational drug.
As a stimulant it can be taken in two forms, a powder which is snorted, or a “rock” that is smoked. The powder, cocaine hydrochloride, is typically snorted through a rolled up tube of paper, such as money, and it is rapidly absorbed from the nasopharyngeal membranes. As the free base, crack cocaine rocks are smoked in a crack pipe, without tobacco, and the resulting fumes absorbed directly into the lung membranes. The high resulting from smoking crack is much stronger than through snorting, and has a very high rate of addiction.
Benzodiazepines
Benzodiazepines are a class of drugs that act on the central nervous system giving mostly sedative effects. These sedatives are mainly prescribed for insomnia (hypnotics) or to reduce anxiety (anxiolytics), but they are also commonly co-prescribed, especially with anaesthetics, during ventilation, as a muscle relaxant, for status epilepticus and to ease alcohol withdrawal symptoms.
There were many people made dependent on benzodiazepines by long term prescription, although guidelines on their use make prescribers more aware of potential addiction. However, there are still 1-1.5 million people prescribed benzodiazepines each year in the UK, about half the level of the late 1970’s.
Drug users take benzodiazepines for a combination of the above effects. They will enhance the effects of heroin and other narcotics, and also offset some of the stimulant effects of amphetamines. The calming effects of tranquillisers are also popular as an escape mechanism. Some addicts will inject the stronger benzodiazepines such as temazepam if access to heroin is limited, although it is far more common to take the tablets.
Cannabis
Cannabis is the name given to the drug obtained from Cannabis sativa, either as the dried leaves or as the hardened resin. Cannabis is normally smoked in a “joint”, usually a mixture of tobacco and cannabis rolled up in a cigarette paper, although it can also be eaten as “hash cakes” or smoked without tobacco. Cannabis is the commonest recreational drug in the UK, and is used by around 2 million people in the UK on an occasional basis, with 8.5 million people having tried it at least once.
Cannabis generally relaxes users and gives a mellow feeling, although use of strong cannabis varieties can give hallucinogenic effects. Cannabis use can also have severe psychiatric effects, leading to psychosis in some people.
Cannabinoids are generally lipid soluble, and they are rapidly absorbed into the fatty tissues such as brain and adipose tissue. This makes it very difficult to measure cannabis in blood or to give any idea of the level of intoxication, and blood levels of cannabis can actually decrease during smoking.
Barbiturates
Barbiturates are a group of drugs with properties that range from sedative to hypnotic to anti-convulsant. Barbiturates can be classified according to their duration of action. Some short acting barbiturates, such as hexobarbital, have a half life of only 3-7 hours, while longer acting barbiturates have half lives of 30-40 hours (butobarbital) or as much as 90-100 hours (Phenobarbital).
Phenobarbital in particular has been used to “cut” heroin, as it acts both as a cheap filler and also helps to make smoking easier, and unknown barbiturate addiction can present added complications to a patient in rehabilitation and detox.
Sample Requirements
Please send at least 30mL in a plain universal container for a full drug screen. Very small samples will be accepted, but they may not be adequate for full testing and confirmation.
Please list all drugs taken in the past week, if available.
Storage and Transport
Refrigerate if possible and send by first class post to:
Toxicology Unit
Top Floor, Bessemer Wing
King's College Hospital
Denmark Hill
London
SE5 9RS
If possible, please complete the request form attached and send as a hard copy (do not send electronically) with the sample. This will ensure all relevant information is available and will aid us in processing your test.
PDF Request Form
Download Routine Drug Screen Request Form
Turnaround Time
Preliminary results are normally available same day. Confirmation and classification of opiates and amphetamines may take up to 1 week.
Time Limit for Extra Tests
Samples will be kept for 7 days from receipt. Additional drug tests may be requested during this time if required.
Please list all medication (excluding food or vitamin supplements) to enable a full interpretation.
Price
Price available on application - please contact adrianturner1@nhs.net. Discounts could be available for significant workloads.
Contacts
Ms Michelle Birch
Tel: 020 3299 5883
Fax: 020 3299 5888
Simon Handley
Tel: 020 3299 5881
Fax: 020 3299 5888
