Chronic users

ACETAMINOPHEN. Acetaminophen is usually well tolerated, and few adverse reactions are seen if die drug is given in recommended amounts. It is important not to exceed die recommended dosage of acetaminophen. If die patient is an alcoholic or chronic user of alcohol, acetaminophen intake is limited to no more tiian 2 g/d. 

DSM-IV-TR (American Psychiatric Association 2000) criteria for hallucinogen intoxication are presented in Table 6-3. The normally used quantity of LSD ingested ranges from 30 to 400 pg, but doses as low as 20 pg may cause clinically detectable symptoms (Strassman 1984). However, tolerance to the effect of LSD develops relatively quickly, so that chronic users increase their dose over time. 

Given the low incidence of severe withdrawal symptoms and the modest effects on the mesolimbic dopamine (reward) system, most investigators have found that cannabis has a low abuse or addiction potential. However, it has been argued that if cannabis is a non-addictive substance, why is its use so widespread and why are there so many longterm and heavy users Finally, contrary to the evidence that cannabis can produce chronic tolerance, some regular users report that they require less drug to achieve the same high, or sensitisation (Chapter 3). Three possible explanations may account for this. First, chronic users may focus on the effects that they wish to achieve. Second, the... 

Acute physiological responses to opiate administration occur rapidly and include constricted pupils, decreased pulse rate, reduced body temperature, slowed respiration rate and impaired reflexes. In addition, there is a marked slowing of the digestive system through an altering of the tonus and motility of the stomach and intestines, allowing for greater water absorption. This last effect is not subject to tolerance, and constipation is a common side effect even for chronic users. Indeed, some report that this is the worst side effect of opiate use. 

THC is detectable on toxicologic screening for up to 4 to 5 weeks in chronic users. 

Flashbacks may occur, especially in chronic users. It produces tolerance but is not addictive. 

Route of administration alters the effectiveness of cannabinoids. Orally administered THC has a slower and more erratic absorption. THC was found to be 45 times more effective for analgesia after intravenous than after subcutaneous administration (Martin 1985). The pharmacokinetics of different chemical constituents of cannabis vary (Consroe et al. 1991). The elimination half-life of cannabidiol is estimated to be about 2-5 days, with no differences between genders. Comparably, the elimination half-life of Al-THC is approximately 4 days, and may be prolonged in chronic users (Johansson et al. 1988, 1989). 

The effects of cannabis on cognition is a complicated issue. Numerous studies have been conducted to measure the mental effects of cannabis, but many of these are fraught with methodological problems. Several variables must be controlled in this type of research, including the dosage and potency of cannabis used, route of administration (e.g., smoking, oral, etc.), chronicity of dose, and the subject population (nonusers, occasional users, chronic users) employed (table 10.7). Population makeup has a large effect on outcome because there have been differences demonstrated between naive and experienced cannabis users (Murray 1986). 

A study of experienced cannabis smokers tested them on cognitive measures using two doses (1.75% or 3.55%) and placebo (Wilson et al. 1994). The functions most sensitive to the effects of THC were mental processing speed (digit-symbol substitution) and reaction time. When compared with cannabis nonusers, chronic users of cannabis—with a mean duration of use of 6.76 years and an average daily intake of 150 mg of THC—were found to have slower reactions on perceptuo-motor tasks, but no differences on intelligence or memory tests (Varma et al. 1988). 

Auditory hallucinations consist typically of voices making derogatory personal statements may also occur. They are frightening and may prompt aggressive and violent behaviour (O Brien Woody, 1994). The hallucinations in these drug-induced states in chronic users occur in an otherwise clear consciousness, but similar hallucinations occur in the delirium which may follow acute intoxication with these drugs or in their withdrawal reactions. 

That a low dose was administered only once or a very few times in the Army research does not completely rule out the possibility that a vulnerable subject might have developed a delayed psychotic reatlon. The dose given by mouth In Edgewood experiments was up to 5 mg—a modest amount, but one that should produce some symptoms of Intoxication in most nontolerant subjects.1- Other subjects Inhaled unknown amounts In aerosol form. Table 3-4 lists the clinical effects of various doses of SNA. Doses of 250 mg and more have been Ingested by chronic users after the development of tolerance. In comparison, 5-10 mg intravenously can result in delirium, 20 mg In coma, and 50 mg In convulsions. 

Targownik LE et al The relative efficacies of gastroprotective strategies in chronic users of non-steroidal anti-inflammatory drugs. Gastroenterology 2008 134 937. [PMID 18294634]... 

In animals (particularly monkeys), cannabis depresses ovarian and testicular function. In man, chronic use has been associated with reduced serum FSH and LH concentrations in a few people, often accompanied by reduced serum testosterone, oligospermia, reduced sperm motility, and gynecomastia (235). There is no evidence of impairment of male fertility no studies have been carried out on female fertility. There is evidence of slightly shortened gestation periods in chronic users (236). There are variable non-specific effects on serum prolactin and growth hormone and a rise in plasma cortisol concentrations has been recorded in one study. 

Today, however, it is known that the manner in which absinthe was once prepared would have produced only very low levels of thujone in a typical serving. Therefore, the symptoms noted among chronic users of absinthe more likely resulted... 

Tolerance to the effects of marijuana clearly exist even though chronic users have described a reversed tolerance and claim that smaller doses of the drug are necessary to produce the desired effects. This effect is probably related to the manner of use and the expectations of the user. Chronic, high-dose cannabis users may experience an abstinence or withdrawal syndrome on abrupt discontinuation of use. Signs and symptoms include irritability, restlessness, nervousness, weight loss, insomnia, and rapid eye movement (REM) rebound. Onset of this syndrome is several hours after the last dose, and it lasts 4 to 5 d. Because withdrawal is not life-threatening, treatment involves little more than supportive therapy with short-term, low doses of benzodiazepines. 

Chronic constipation is also another troublesome side effect of prolonged methadone use. As discussed previously, methadone significantly slows the involuntary movements of the small and large intestines. By consuming a high-fiber diet and plenty of water, chronic users of methadone can reduce, but not eliminate, the occurrence of constipation. 

Methamphetamine is a white, odorless, bitter-tasting powder that dissolves easily in water or alcohol. Methamphetamine production begins with a common chemical known as ephedrine. After using several toxic chemicals, including hydriodic acid, chemical solvents, and heavy metals such as mercury and lead, methamphetamine is produced. Chronic users often combine... 

It is this oxygen deprivation that sometimes causes a bluish tinge on the lips of chronic nitrous abusers. After the initial high of nitrous wears off, chronic users may also experience such varied side effects as nausea, visual disturbances (seeing spots), feelings of claustrophobia, fatigue, and difficulty concentrating. 

Some people who take PCP experience symptoms very similar to those seen in people with schizophrenia, including delusions, paranoia, memory problems, confusion, disordered thinking, and impaired speech. This is called PCP organic mental disorder. Such schizophrenialike episodes usually last several days, but they may last weeks or months after taking the drug only once. Such a reaction is most common in chronic users, but it can... 

Even when taken at recommended dosages, Rohypnol can cause dependence and addiction among frequent users. Some people addicted to Rohypnol experience seizures when they attempt withdrawal from the drug. The U.S. Department of Justice says such seizures may occur among chronic users after as little as one week without Rohypnol. 

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