Classified as a Central Nervous System (CNS) stimulator and was first used as a treatment of narcolepsy and depression; this class of drugs includes amphetamine, methamphetamine, phenmetrazine, methylphenidate, diethylpropion, and propylhexedrine. Methamphetamine is currently the most frequently encountered clandestinely produced controlled substance in the US. Brand names include Dexedrine, Benzedrine Desoxyn, and Methedrine. Amphetamines are used in the treatment of narcolepsy, ADD or Hyperactivity Disorder and some forms of depression. Many OTC cold remedies contain amines which are similarly structured compounds. Pseudophedrine (Sudafed, Actifed, Contac and Drixoral), Phenylephedrine (Dristan, Neosynepherine) and ephedrine (Primatene and Bronkaid) are a few OTC that may be detected. Using a cut-off level of 1000 ng/ml may help differentiate the detection of patients who periodically use OTC as opposed to actual abusers. Amphetamines may be detected for up to four days. Up to 30% of the drug is excreted in the urine.
Barbiturates are one of the oldest classes of CNS depressants dating back to the early 1900’s. Widely used today they are primarily indicated for use as a sedative-hypnotic, as anticonvulsants, in migraine therapy, and for the reduction of cerebral edema secondary to head injury. They are often classified according to their duration of action—ultra short acting to long acting. Brand names include secobarbital, amobarbital, pentobarbital, butabarbital, butalbital and phenobarbital. Screening is done for the class of drug. Cross-reaction is almost non-existent. Detection time is up to 10 days. Phenobarbital may be detected for up to 30 days.
As a class, benzodiazepines are some of the most widely prescribed drugs in the world and have largely replaced barbiturates as the major class of CNS depressant drugs. These are structurally related drugs all of which have the ability to act as sedatives and hypnotics. They have a wide therapeutic index or a wide margin between medical benefits and toxicity. Common benzodiazepines include Librium (chlordiazepoxide), Valium (Diazepam), Dalmane (Flurazepam), Serax (oxazepam), Ativan (lorazapam), Temazepam, Bromazepam, clonazepam (Clonopin), and alprazolam (Xanax) Benzodiazepines are used in the treatment of anxiety and insomnia. When abused it is almost always in conjunction with another drug or alcohol. Screening is done for the class of drug with very little cross-reactivity to other drugs. Zoloft (sertraline) will cross-react with this class. Detection may be as soon as one (1) hour after ingestion for fast acting benzodiazepines and may remain detectable for up to14 days for some of the long acting varieties. This group of drugs contains over 2,000 drugs.
Muscle relaxants are drugs that act to reduce tension in muscles. The mechanism through which this is accomplished depends on the type of muscle relaxant. “Neuromuscular blockers” function by blocking neuromuscular transmission at the end plate of the neuromuscular junction. This results in temporary paralysis, as the muscle is unable to contract. Neuromuscular blockers are often used during anesthesia. “Spasmolytics” (often referred to as “centrally acting muscle relaxants”) function by either inhibiting the delivery of signals that excite the motor neuron or enhancing the delivery of signals that inhibit excitement of the motor neuron. The end result is the prevention of muscle spasms. Spasmolytics are often used to treat lower back pain, muscle spasms and Fibromyalgia. Commonly prescribed muscle relaxants include: Carisoprodol (Soma), Cyclobenzaprine (Flexeril) Metaxalone (Skelaxin), Baclofen (Lioresal, Liofen) and Diazepam (Valium) to name a few. Long-term users of muscle relaxants can become physically dependent and suffer withdrawal symptoms. Abuse is common especially in patients who have a history of drug or alcohol abuse.
Opiates are a naturally occurring alkaloid obtained from the opium poppy. These drugs have been used for more than 2000 years. There are several pharmacological active compounds derived from the poppy including morphine and codeine. Opiates are broadly classified into three groups depending on their mode of action. Agonists which include Morphine, Heroin, Hydrocodone, Oxycodone, Propoxyphene and Codeine produce euphoria, analgesia and increased tolerance to pain. Antagonists such as Naloxone inhibit agonist binding for the receptor sites making theses drugs effective in countering overdoses of agonists. Detection time is up to three days following therapeutic use of Codeine or Morphine, longer with Heroin High doses of Morphine can result in the formation of Hydromorphone from a reaction with E. coli in the intestine. Hydrocodone brand names – Lortab, Lorcet, Norco, Vicodin, Vicoprofen and Zydone. Hydromorphone brand names – Dilaudid and Palladone. Oxycodone brand names – Oxycodone, Oxycontin, M-OXY, Roxicodone, Endocet, Percocet, Tylox, Roxicet and Percodan. Morphine brand names – Astramor, Avinza, Duramorph, Kadian, Morphine Sulfate, MS Contin, MSIR, Oramorph, Roxanol, MS/L, MS/S, OMS and RMS.
Tricyclic antidepressants emerged on the market with the synthesis of Chlorpromazine in 1950 by French Chemist, Paul Charpentier. This drug was initially used as an antipsychotic. Imipramine was the first TCA used to treat depression. TCAs combat depression by acting as a Serotonin-norepinephrine inhibitor (SNRI), which effectively increases norepinephrine and serotonin concentrations in the brain. For many years, TCAs served as the primary means of treating clinical depression until newer antidepressants emerged that had less severe side effects. Despite the emergence of these newer drugs, TCAs remain an effective means of treating depression and other mood disorders. TCAs are often used successfully when patients are non-responsive to the newer forms of antidepressants. Cytochrome P450 inhibitors such as Fluoxetine, Methylphenidate and various antipsychotics, act to decrease the metabolism of TCAs resulting in higher drug concentrations when testing. These higher concentrations can potentially lead to toxicity and overdose. Ingestion of TCAs will intensify the effects of central nervous system depressants such as alcohol and barbiturates. Common TCAs sold in the United States include: Clomipramine (Anafranil), Imipramine (Tofranil, Janimine, Praminil), Nortriptyline (Pamelor, Aventyl, Norpress), Amitriptyline (Tryptomer, Elavil, endep), Doxepin (Adapin, Sinequan) and Trimipramine (Surmontil).
Methadone was synthesized during WWII as a substitute for Morphine. It differs from Morphine in that its oral activity is similar to its intravenous potency and that it has a long terminal elimination half-life. It is prescribed in drug treatment programs in liquid form. Brand names include Dolophine and Methadose. Absorption and excretion are influenced by an individual’s metabolism, urinary pH, diet, pregnancy and other medications. Ingesting large quantities of Vitamin C may decrease the effects of morphine. Grapefruit juice may increase effects and result in higher than expected levels. Barbiturates may decrease effects and results in patients requesting higher dosage. Buprenorphine, Naltrexone and Naloxone used in conjunction with methadone may result in withdrawal symptoms.
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