Agencies of government, industries, education, and sports are requiring testing for drugs of abuse of prospective and existing employees, students for admission/returning students, and participants in professional and amateur athletics. Drug abuse during pregnancy also is of immense concern, both for medical and social reason. In addition, testing for drugs of abuse may be used medically for the following:
(1) organ transplantation candidates
(2) pain management clinics,
(3) drug abuse treatment programs, and
(4) psychiatric programs.
Drug testing for these purposes represents a significant activity for toxicology and clinical laboratories.
lateral flow urine test for drugs of abuse
LABORATORY DIAGNOSIS
Testing for drugs of abuse usually involves testing a single urine sample for a number of drugs. It should be noted however, that a single urine drug test detects only fairly recent drug use; it does not involve the differentiation of casual use from chronic drug abuse. The latter requires sequential drug testing and clinical evaluation. Urine drug testing also does not determine the following:
(1) degree of impairment
(2) the dose of drug taken or
(3) the exact time of use.
Because of these and other limitations of testing for drugs in urine, there is growing interest in the use of alternate biological sample for drug testing.
Immunochromatographic assays are available for the diagnosis of drugs of abuse at instant. This involves a lateral flow test, using a lateral flow device. A freshly voided urine in the container provided. Manufacturer’s instruction must be adhered to strictly.
Below is an example of laboratory test of drugs of abuse.
DRUG CLASSES MEASURED IN THE WORKPLACE DRUG TESTING PROGRAM
NIDA FIVE
- Amphetamine/methamphetamine
- Cannabinoids
- Cocaine
- Opiates
- Phencyclidine (PCP)
OTHERS
- Benzodiazepines
- Barbiturates
- Lysergic Acid diethylamide (LSD)
- Methylenedioxyamphetamine (MDA)
- Methylenedioxymethamphetamine (MDMA)
- Methylenedioxyethylamphetamine (MDEA)
- Methadone
- Propoxyphene
METHOD OF ACTION OF CLASES OF DRUGS OF ABUSE
Amphetamine, Methamphetamine, and Related Sympathomimetic Amines
Amphetamine and methamphetamine are central nervous system (CNS) stimulant drugs that have limited legitimate pharmacological use. For example, they are used to treat narcolepsy, obesity, and attention-deficit hyperactivity disorders. However, they produce euphoria and have a high abuse potential. Other sympathomimetic amines that also have high potential for abuse include (1) the “designer” amphetamines (MDMA, MDA), (2) Ephedrine, (3) Pseudoephedrine, (4) Phenylpropanolamine, and (5) methylphenidate (Ritalin).
These drugs are sympathomimetic amines that have a stimulating effect on both the central and peripheral nervous systems. These effects include the following;
- Increase blood pressure, heart rate, body temperature and motor activity;
- Relax bronchial muscle;
- Depress the appetite.
Their abuse may lead to strong psychic dependence, notable tolerance, and mild physical dependence associated with the following:
- Tachycardia
- Increased blood pressure
- Restlessness
- Irritability
- Insomnia
- Personality changes
- The severe form of chronic intoxication psychosis similar to schizophrenia.
These unpleasant responses reinforce the repetitive use of the drugs to maintain the “high.” In extreme cases, addicts may have “speed runs,” in which large IV doses are used for several days during which they do not sleep or eat. This is followed, when exhaustion intervenes, by prolonged sleep for 1 or more days after which they awaken hungry but depressed, leading to repetition of the cycle. Tolerance and psychological dependence develop with repeated use of amphetamines. Long-term effects may include depression and impaired memory and motor skills.
Ephedrine and Pseudoephedrine
These amines are diastereoisomeric adrenergic agonists. Ephedrine causes more prominent bronchodilation (B-adrenergic action) than pseudoephedrine and is present in some nonprescription medications for the treatment of asthma. Many dietary supplements contain ephedra, the herbal form ephedrine. These products were widely marketed for weight loss and are used by some athletes who believe they enhance performance. Ephedra-containing pills have been sold as a safe “herbal ecstasty.” Adverse effects of ephedrine and ephedra includes:
- Elevated blood pressure
- Palpitations
- Agitation
- Psychiatric disturbance
- Myocardial infarction
- Seizures
- Cerebral hemorrhage
- Death
Adverse reactions are more likely with high does, or when co-ingested with caffeine or other stimulant drugs, or with preexisting cardiovascular disease or seizure disorders. Ephedra sales are banned in the United States and many other countries.
Phenylpropanolamine (PPA)
Causes hemorrhagic stroke, especially in women.
BARBITURATES
They have high abuse potential. They are used as sedative-hypnotics (amobarbital, butabarbital, butalbital, pentobarbital, and secobarbital) are the most commonly abused. It suppresses the CNS neuronal activities and thus have sedative and hypnotic activities.
BENZODIAZEPINES
These are group of compounds having a common molecular structure and acting similarly as depressants of the CNS. They have anxiolytic, sedative-hypnotic, muscle relaxant, and anti-convulsant properties. They have low addiction potential.
CANNABINOIDS
They are group of compounds found in the plant species Cannabis sativa. The principal psychoactive cannabinoid is tetrahydrocannabinol (THC). The psychoactive effects are euphoria and a sense of relaxation. And well-being. Associated with this “high” are a loss of short-term memory and impairment of intellectual performance. (recall, reading, comprehension, ability to concentrate, and mathematical problem solving). Also psychomotor skills may be sufficiently impaired to adversely affect automobile or airplane operating performance.
CONCAINE
This is an alkaloid, present in the leaves of coca plant that grows in South America. It is a potent CNS stimulant that elicit a state of increased alertness and euphoria with its actions similar to those of amphetamine but of shorter duration. Acute cocaine toxicity result to mydriasis, diaphoresis, hyperactivity bowel sounds, tachycardia, hypertension, hyperthemia, hyperactivity, agitation, seizures, coma. Sudden death come as a result of cardiotoxicity.
OPIODS/OPIATES
This a name for substances that possess morphinelike properties. Opium contains smaller amount of codeine. Some semisynthetic derivatives of morphine include heroin, oxycodone, hydrocodone, oxymorphone, hydromorphone, levorphanol. They cause sedation, euphoria, respiratory depression, orthostatic hypotension, diminished intestinal motility, nausea, vomiting. Coma, miosis (pinpoint pupils) and respiratory depression are seen in over dose.
METHADONE
This is an opioid with structure similar to propoxyphene. In over dose it causes CNS and respiratory depression, miosis, bradycardia, hypotension, circulatory collapse, hypothermia, coma, seizures, pulmonary edema,
PHENCYCLIDINE (PCP) AND KETAMINE
Phencyclidine and ketamine share same properties structurally and pharmacologically. It is used because it causes alteration of the mind, it was called “peace pill” in the 1960’s. it adverse effects include, euphoria, dysphoria, ataxia, nystagmus, agitation, anxiety, paranoia, amnesia, seizures, muscle rigidity, hostility, delirium, delusions of grandeur and hallucinations. A sense of superhuman strength coupled with lack of pain perception may lead to excessive physical exertion and accidental or intentional self-induced trauma.
REFERENCES
CURRENT Medical Diagnosis and Treatment 2013 Papadakis et. al.
TIETZ Fundamentals of Clinical Chemistry Burtis et. al.
Turacos Medical Laboratory