Benzodiazepines act on which receptors?

Correct Answer: A

Rationale: Benzodiazepines act on GABAA receptors. This is the correct answer because benzodiazepines enhance the inhibitory effects of GABA (gamma-aminobutyric acid) at the GABAA receptors in the central nervous system. GABA is the main inhibitory neurotransmitter in the brain, and by enhancing its effects, benzodiazepines exert their anxiolytic, sedative, and muscle relaxant properties. Option B, GABAB receptors, is incorrect because benzodiazepines do not directly act on GABAB receptors. GABAB receptors are metabotropic receptors that are activated by GABA but do not play a direct role in the mechanism of action of benzodiazepines. Option C, both of the above, is incorrect because benzodiazepines specifically target and modulate the activity of GABAA receptors, not GABAB receptors. Selecting this option indicates a lack of understanding of the specific pharmacological targets of benzodiazepines. Option D, none of the above, is incorrect as benzodiazepines do act on GABAA receptors. Choosing this option would demonstrate a fundamental misunderstanding of the mechanism of action of benzodiazepines. Understanding the pharmacological targets of benzodiazepines is crucial for healthcare professionals, especially for those prescribing or administering these drugs. Knowledge of how benzodiazepines modulate GABA receptors helps in understanding their therapeutic effects and potential side effects, leading to safe and effective patient care.

Correct Answer: B

Rationale: In the treatment of seizures, maintaining therapeutic plasma levels of phenobarbital is crucial for optimal control of seizures while minimizing side effects. The correct answer, option B (10-20 µg/ml), is appropriate for seizure control because it falls within the therapeutic range for phenobarbital. Option A (2-5 µg/ml) is too low to effectively control seizures, while options C (50-60 µg/ml) and D (80-90 µg/ml) are too high and may increase the risk of toxicity without providing additional benefit in seizure control. Educationally, understanding the therapeutic range of CNS drugs like phenobarbital is essential for healthcare professionals, especially those involved in managing patients with epilepsy or other seizure disorders. Knowing the appropriate plasma levels helps in adjusting dosages, monitoring efficacy, and minimizing adverse effects. This knowledge ensures safe and effective pharmacological treatment for patients with neurological conditions.

Correct Answer: C

Rationale: In alcohol withdrawal syndrome, constricted pupils are not a typical feature. This is because alcohol withdrawal commonly presents with dilated (not constricted) pupils due to the hyperadrenergic state associated with withdrawal. A) Seizures can occur in alcohol withdrawal due to the imbalance of neurotransmitters in the brain as alcohol suppresses excitatory neurotransmitters. B) Hypertension is often seen in alcohol withdrawal due to increased sympathetic activity. D) Delirium tremens is a severe manifestation of alcohol withdrawal characterized by altered mental status, tremors, hallucinations, and autonomic hyperactivity. Educationally, understanding the symptoms of alcohol withdrawal is crucial for healthcare professionals, especially those working in addiction medicine or emergency settings. Recognizing these symptoms promptly can guide appropriate management and prevent potentially life-threatening complications associated with alcohol withdrawal. Understanding the nuances of alcohol withdrawal can improve patient outcomes and safety.

Correct Answer: C

Rationale: In pharmacology, nalorphine is a medication that acts as a mixed opioid agonist-antagonist. The correct answer is C) Pethidine (also known as meperidine). Nalorphine is not used as an antidote for pethidine poisoning because pethidine is a synthetic opioid analgesic, and nalorphine's antagonist effects are more effective against natural opioids like morphine and heroin. A) Morphine: Nalorphine is used as an antidote for morphine overdose due to its opioid antagonist properties. It can reverse the effects of morphine by blocking its actions at opioid receptors. B) Pentazocine: Nalorphine is used as an antidote for pentazocine overdose. Pentazocine is a mixed opioid agonist-antagonist similar to nalorphine, so nalorphine can effectively counteract its effects in cases of overdose. D) Heroin: Nalorphine is also used as an antidote for heroin overdose. Heroin is a natural opioid derivative, and nalorphine's antagonistic actions help reverse its effects in cases of overdose. In an educational context, understanding the specific antidote for opioid overdose is crucial for healthcare professionals, particularly in emergency situations. Knowing which opioids nalorphine is effective against helps in providing appropriate and timely interventions to manage opioid toxicity and prevent serious complications or fatalities. This knowledge is essential for healthcare providers working in settings where opioid use and overdose are prevalent.

Correct Answer: D

Rationale: Ephedrine is similar to adrenaline in respect to both α and β adrenergic effects. This is the correct answer because ephedrine, like adrenaline, acts on both α and β adrenergic receptors in the sympathetic nervous system. This similarity in receptor activity is important in understanding the pharmacological effects of ephedrine in the body. Option A) Duration of action is incorrect because ephedrine and adrenaline have different durations of action due to variations in metabolism and clearance rates. Option B) Potency is incorrect because ephedrine and adrenaline differ in their potency in activating adrenergic receptors. Option C) Penetration of blood-brain barrier is incorrect because while adrenaline does not easily cross the blood-brain barrier, ephedrine can penetrate the blood-brain barrier to some extent. In an educational context, understanding the similarities and differences between ephedrine and adrenaline in terms of their adrenergic effects is crucial for pharmacology students and healthcare professionals. This knowledge helps in predicting and managing the pharmacological effects and potential side effects of ephedrine in clinical practice, especially in conditions where adrenergic stimulation is required.