Which of the following is a recently developed antiepileptic drug used mainly as add-on therapy of refractory partial seizures?

Correct Answer: B

Rationale: The correct answer is B) Lamotrigine. Lamotrigine is a recently developed antiepileptic drug that is commonly used as add-on therapy for refractory partial seizures. It has been found to be effective in reducing seizure frequency and is well-tolerated by many patients. Option A) Viloxazine is not an antiepileptic drug but rather a selective norepinephrine reuptake inhibitor used in the treatment of depression and anxiety disorders. Option C) Bupropion is primarily used as an antidepressant and for smoking cessation. It is not indicated for the treatment of epilepsy. Option D) Clozapine is an atypical antipsychotic used in the treatment of schizophrenia and treatment-resistant bipolar disorder. It is not an antiepileptic drug. Understanding the differences between these drugs is crucial in clinical practice to ensure appropriate treatment selection based on the patient's condition. Pharmacology of CNS drugs is a fundamental component of medical education, particularly in fields like neurology and psychiatry. It is essential for healthcare providers to have a strong grasp of the mechanisms of action, indications, and side effects of these drugs to make informed decisions in patient care.

Correct Answer: B

Rationale: In the context of the pharmacology of CNS drugs, understanding the adverse effects associated with neuroleptic medications is crucial. The correct answer to the question is B) Extrapyramidal motor disturbances. This adverse effect is positively correlated to the antipsychotic potency of the different compounds. Extrapyramidal motor disturbances encompass a range of movement disorders such as dystonia, akathisia, parkinsonism, and tardive dyskinesia. These side effects are more prominent in high-potency neuroleptic drugs due to their strong blockade of dopamine receptors in the brain, particularly the D2 receptors. This blockade leads to an imbalance in dopamine levels, resulting in the development of extrapyramidal symptoms. Option A) Sedation is a common side effect of many CNS drugs but is not directly correlated with antipsychotic potency. Option C) Postural hypotension is more commonly associated with alpha-adrenergic blockade seen in some antipsychotic medications rather than antipsychotic potency. Option D) Lowering of seizure threshold is not a direct indicator of antipsychotic potency but rather a potential side effect seen with certain medications affecting GABAergic or glutamatergic neurotransmission. Educationally, understanding the relationship between antipsychotic potency and adverse effects helps healthcare professionals make informed decisions when prescribing CNS drugs. By recognizing the side effect profile associated with different compounds, clinicians can tailor treatment plans to minimize adverse effects and improve patient outcomes.

Correct Answer: C

Rationale: The correct answer is C) Fluoxetine. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI), which means it selectively blocks the reuptake of serotonin (5-hydroxytryptamine) in the brain. This action leads to increased levels of serotonin in the synaptic cleft, which is beneficial in treating depression. Desipramine (option A) is a tricyclic antidepressant that primarily acts by blocking the reuptake of norepinephrine and to a lesser extent serotonin. Amoxapine (option B) is a tetracyclic antidepressant with mixed effects on various neurotransmitters including serotonin. Dothiepin (option D) is another tricyclic antidepressant that primarily inhibits the reuptake of norepinephrine. Understanding the mechanisms of action of different classes of antidepressants is crucial for healthcare professionals, especially pharmacists and physicians, when making treatment decisions for patients with depression. Knowing the specific actions of each drug helps in selecting the most appropriate medication based on the patient's symptoms, medical history, and potential side effects. This knowledge also aids in monitoring for efficacy and adverse reactions during treatment.

Correct Answer: D

Rationale: In understanding why strychnine produces convulsions by blocking the inhibitory transmitter glycine, it is crucial to delve into the pharmacological mechanism of action. Glycine is an inhibitory neurotransmitter in the central nervous system that binds to glycine receptors, causing hyperpolarization of the postsynaptic neuron and thus inhibiting its activity. By blocking glycine receptors, strychnine prevents this inhibitory effect, leading to excessive excitatory neuronal activity and ultimately convulsions. Looking at the other options: A) Stimulating NMDA receptors: NMDA receptors are associated with excitatory neurotransmission, but strychnine does not act by directly stimulating these receptors. B) Facilitating the excitatory transmitter glutamate: While glutamate is the primary excitatory neurotransmitter in the CNS, strychnine's mechanism of action does not involve facilitating its effects. C) Blocking the inhibitory transmitter GABA: While GABA is another major inhibitory neurotransmitter in the CNS, strychnine specifically acts by blocking glycine receptors, not GABA receptors. In an educational context, understanding how different drugs interact with specific neurotransmitter systems is foundational in pharmacology. This knowledge is essential for healthcare professionals to predict and explain the effects and side effects of various drugs on the central nervous system, enabling them to make informed decisions in clinical practice. Understanding the specific effects of strychnine on glycine receptors also provides insights into the broader principles of neurotransmission and synaptic modulation in the CNS.

Correct Answer: C

Rationale: In the context of treating congestive heart failure (CHF), the correct answer is C) Enalapril. Enalapril is an angiotensin-converting enzyme (ACE) inhibitor, which helps to improve cardiac function and reduce the workload on the heart by dilating blood vessels and reducing blood volume. This is especially beneficial in CHF where the heart is struggling to pump effectively. Option A) Digoxin is a cardiac glycoside often used to treat heart failure, but it primarily helps to increase the strength of the heart's contractions rather than addressing the underlying causes of CHF. Option B) Furosemide is a loop diuretic that helps to reduce fluid overload in the body by increasing urine output. While it can alleviate symptoms of fluid retention in CHF, it does not address the primary cause of the condition. Option D) Amrinone is a phosphodiesterase inhibitor that increases the force of cardiac contractions. While it can be used in some cases of CHF, it is not as commonly prescribed as ACE inhibitors like enalapril. In an educational context, understanding the rationale behind choosing the most appropriate medication for CHF is crucial for healthcare professionals to provide optimal care for patients. By knowing the mechanism of action and the specific benefits of each medication, practitioners can make informed decisions based on the underlying pathophysiology of the condition. This knowledge helps to improve patient outcomes and minimize potential adverse effects.