Which of the receptors is implicated in the respiratory depressant action of opioids?
A. Mu (MOP) receptors are found in the brain in the cortex, thalamus, striosomes, and periaqueductal grey. The Mu1 subtype is responsible for supraspinal analgesia and physical dependence. The Mu 2 subtype is responsible for respiratory depression, euphoria, constipation, physical dependence, and miosis. Kappa (KOP) receptors are found in the hypothalamus, claustrum, and periaqueductal grey regions of the brain and the substantia gelatinosa of the spinal cord. They are involved in spinal analgesia, sedation, miosis, and inhibition of ADH release. Delta (DOP) receptors are seen in the brain in the regions of the pons, amygdala, olfactory bulbs, and the deep cortex. Their function includes analgesia, euphoria, and physical dependence. Sigma receptors, which mediate the antitussive action, are no longer considered to be opioid receptors. A new receptor called ORL1 has recently been identified, with an endogenous ligand called nociceptin. The ORL1 receptors do not bind opioid peptides or opiate drugs. This system is widely distributed in the brain and spinal cord. Its activation produces hyperalgesia in most instances. Many do not consider ORL1 as an opiate receptor. The International Union of Basic and Clinical Pharmacology has recently agreed to rename mu, kappa, and delta to MOP, KOP and DOP receptors respectively.
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What is the equivalent dose of methadone for 0.5 g of street heroin?
C. Assessing the methadone dose equivalent of reported street heroin use is difficult because of the reliance on self-report and the variable purity of illicit heroin. Broadly speaking, 30–40 mL of 1 mg/mL mixture is approximately equivalent to 0.5 g of street heroin.
Amotivational syndrome has been described with the use of which of the following substance?
C. A controversial cannabis-related syndrome is amotivational syndrome. Whether the syndrome is related to cannabis use or refl ects characterological traits in a subgroup of people regardless of cannabis use is under debate. Traditionally, amotivational syndrome has been associated with long-term heavy use and has been characterized by a person’s unwillingness to persist in a task. Persons are described as becoming apathetic and anergic, and appearing indolent. Field studies of chronic heavy cannabis users in societies with a tradition of such use have not produced consistent evidence to demonstrate the existence of amotivational syndrome. Critics have questioned the methodological issues of the study. However, the possibility has been kept alive by reports that regular cannabis users experience a loss of ambition and impaired school and occupational performance.
Maternal smoking during pregnancy has been best associated with which of the following?
C. Maternal smoking during pregnancy has been consistently associated with conduct disorder and delinquency and attention-deficit hyperactivity disorder (ADHD) in offspring during childhood and adolescence. This association has been found even after controlling for confounding variables such as socioeconomic status, maternal age, birth weight, and maternal psychopathology. This may be due to the effect of nicotine or may be genetically mediated. There may be other environmental risks that play a part in its development. More recent research has shown that the behavioural problems may not be a direct risk of smoking itself, but the presence of other genetic factors that may mediate the association between maternal smoking and conduct problems in children.
Following recent consumption of LSD, it can be detected in urine for up to:
B. LSD and its metabolites are detectable in human urine for as long as 4 days after the ingestion of 0.2 mg of the drug. Amphetamines can be detected for 2–4 days; cocaine can be present for up to 3 days. Marijuana users may test positive in urine samples for up to 3 days after casual use; this can extend to up to 30 days for regular high-dose users.
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