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Questions and Answers
Caffeine is not commonly found in tea and chocolate.
Caffeine is not commonly found in tea and chocolate.
False
Theobromine has the strongest pharmacological activity among methylxanthines.
Theobromine has the strongest pharmacological activity among methylxanthines.
False
Theophylline has a narrow therapeutic margin of 10 to 20 μg/mL.
Theophylline has a narrow therapeutic margin of 10 to 20 μg/mL.
True
Diazepam is the first-line therapy for managing theophylline-induced seizures.
Diazepam is the first-line therapy for managing theophylline-induced seizures.
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Theophylline can stimulate the CNS, but it does not cause diuresis.
Theophylline can stimulate the CNS, but it does not cause diuresis.
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Accumulation of cyclic AMP can occur due to the action of phosphodiesterase inhibitors.
Accumulation of cyclic AMP can occur due to the action of phosphodiesterase inhibitors.
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Propranolol is effective in managing theophylline-induced cardiac arrhythmias.
Propranolol is effective in managing theophylline-induced cardiac arrhythmias.
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Rapid intravenous administration of theophylline can lead to death due to respiratory failure.
Rapid intravenous administration of theophylline can lead to death due to respiratory failure.
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Severe restlessness is not a symptom associated with theophylline overdose.
Severe restlessness is not a symptom associated with theophylline overdose.
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Caffeine enhances the analgesic properties of salicylates in multiple products.
Caffeine enhances the analgesic properties of salicylates in multiple products.
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Camphor is typically considered toxic by laypeople.
Camphor is typically considered toxic by laypeople.
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Camphor can produce symptoms of poisoning within a timeframe of 5 to 15 minutes after ingestion.
Camphor can produce symptoms of poisoning within a timeframe of 5 to 15 minutes after ingestion.
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Barbiturates are preferred over diazepam for controlling convulsions due to less respiratory depression.
Barbiturates are preferred over diazepam for controlling convulsions due to less respiratory depression.
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Camphor must be removed from the stomach using activated charcoal only.
Camphor must be removed from the stomach using activated charcoal only.
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Hemodialysis is effective in accelerating the removal of camphor from the blood.
Hemodialysis is effective in accelerating the removal of camphor from the blood.
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The effects of camphor poisoning may be delayed several hours if the stomach is full.
The effects of camphor poisoning may be delayed several hours if the stomach is full.
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Camphorated oil is commonly mistaken for sesame oil leading to poisonings.
Camphorated oil is commonly mistaken for sesame oil leading to poisonings.
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Sodium bicarbonate is recommended for the management of camphor poisoning.
Sodium bicarbonate is recommended for the management of camphor poisoning.
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The recommended treatment assumes the quantity of camphor ingested is less than 1 gram if unknown.
The recommended treatment assumes the quantity of camphor ingested is less than 1 gram if unknown.
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Patients with camphor poisoning should be kept in an environment with minimum sensory input.
Patients with camphor poisoning should be kept in an environment with minimum sensory input.
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Amphetamine is primarily used to treat chronic pain conditions.
Amphetamine is primarily used to treat chronic pain conditions.
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Chlorpromazine can reverse the effects of hyperthermia caused by amphetamine toxicity.
Chlorpromazine can reverse the effects of hyperthermia caused by amphetamine toxicity.
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Amphetamines work by inhibiting the release of catecholamines in the central nervous system.
Amphetamines work by inhibiting the release of catecholamines in the central nervous system.
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Visual hallucinations from amphetamine use are common after a single large dose.
Visual hallucinations from amphetamine use are common after a single large dose.
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Tolerance to the euphoric actions of amphetamines means that users often need to decrease their dosage.
Tolerance to the euphoric actions of amphetamines means that users often need to decrease their dosage.
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Amphetamine-induced psychosis can lead to tactile hallucinations that are more common than auditory ones.
Amphetamine-induced psychosis can lead to tactile hallucinations that are more common than auditory ones.
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A significant hyperpyrexia related to amphetamine toxicity can result in body temperatures exceeding 109 oF.
A significant hyperpyrexia related to amphetamine toxicity can result in body temperatures exceeding 109 oF.
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The management of amphetamine poisoning involves the use of salicylates and the administration of a cooling blanket.
The management of amphetamine poisoning involves the use of salicylates and the administration of a cooling blanket.
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Amphetamine toxicity can lead to sympathetic effects such as bradycardia and hypotension.
Amphetamine toxicity can lead to sympathetic effects such as bradycardia and hypotension.
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The release of dopamine into the synaptic spaces is a minor effect of amphetamines.
The release of dopamine into the synaptic spaces is a minor effect of amphetamines.
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Study Notes
Clinical Toxicology: Central Nervous System Stimulants (Amphetamines)
- Amphetamines are used to modify various medical conditions
- Approved for narcolepsy, hyperkinesia (hyperactivity) in children, and short-term obesity treatment
- Numerous amphetamine derivatives exist
- Amphetamines cause CNS stimulation via catecholamine release and inhibiting reuptake
- Amphetamine users often experience tolerance, needing increasing doses
- Prolonged use can significantly lower the convulsive threshold, leading to higher fatality risk
Mechanism of Toxicity
- Amphetamine primarily stimulates the CNS by releasing epinephrine, norepinephrine, and dopamine into synaptic spaces.
- It blocks their reuptake into nerve endings.
- Tolerance to the central effects (like anorexia and euphoria) is a common issue.
- Continued use can lower the convulsive (seizure) threshold, increasing fatality risk.
Characteristics of Poisoning
- Amphetamine poisoning presents various dose-related signs and symptoms.
- Toxic effects extend pharmacological actions, including CNS effects.
- Amphetamine-induced psychosis is common, with euphoria and hallucinations (auditory, visual & tactile).
- Respiratory functions are stimulated.
- Cardiovascular functions are stimulated (tachycardia, hypertension).
- Sympathomimetic effects include flushing, diaphoresis.
- Hyperpyrexia (high temperatures; above 109°F/ 42.8°C) is a serious risk and can result in death.
Management of Amphetamine Poisoning
- Phenothiazines are used to treat amphetamine-induced psychosis due to excess dopamine.
- Chlorpromazine reverses hyperthermia, convulsions, and hypertension.
- Salicylates, hypothermic blankets, or cool, quiet environments help reduce temperature.
Methylxanthine Derivatives
- Theobromine, theophylline, and caffeine are methylxanthine alkaloids found naturally.
- These are commonly present in chocolate, tea, and cola drinks.
- Used in drug therapy (e.g., theophylline) and in analgesic products
Methylxanthines: Mechanism of Toxicity
- Methylxanthines stimulate the CNS and cause diuresis (increased urination).
- They relax smooth muscles (bronchial and cardiac).
- Caffeine strengthens the analgesic effects of salicylates.
- Theobromine exhibits similar (but weaker) effects on the CNS compared to caffeine.
- Increased calcium release from intracellular sites.
- Accumulation of cyclic nucleotides (particularly cyclic AMP) due to phosphodiesterase inhibitors.
- Adenosine receptor blockade causes increased norepinephrine, dopamine, and serotonin release.
Theophylline Poisoning
- Theophylline has a narrow therapeutic margin (10-20 µg/mL).
- Maintaining therapeutic blood levels can be challenging as many factors influence clearance.
- Rapid intravenous administration can lead to fatal cardiac arrhythmias.
- Excessive theophylline can cause nausea, headache, dizziness, tachycardia, hypotension, and precordial pain.
- Severe restlessness and agitation may occur.
- Seizures (focal or generalized) can also occur
Camphor Poisoning
- Camphor quickly enters the CNS due to high lipid solubility.
- Signs and symptoms appear within 5-15 minutes (or delayed hours).
- Management: Remove camphor quickly.
- Immediate emesis or gastric lavage to clear stomach.
- Activated charcoal; lavage until odor is gone.
- Unknown ingestion quantity is assumed to be more than 1g, hence requires vigorous treatment.
Management of Camphor Poisoning
- Barbiturates are no longer the first-line treatment for seizures
- Diazepam is preferred for treating seizures due to its lower respiratory depression risk.
- Hemodialysis can hasten camphor removal.
- Succinylcholine can help manage muscle rigidity and spasms.
- The patient should be kept quiet with minimal sensory input.
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Description
This quiz explores the clinical aspects of amphetamines, including their medical uses, mechanisms of toxicity, and characteristics of poisoning. Understand the effects on the central nervous system and the risks associated with prolonged use and tolerance. Test your knowledge on these critical aspects of toxicology related to CNS stimulants.
