MINI TEST PHARMACOLOGY

A 78-year-old male on long-term anticoagulation with dabigatran for non-valvular atrial fibrillation undergoes an emergency laparotomy for a perforated viscus. He experiences significant intraoperative bleeding that is difficult to control. Which of the following is the most appropriate agent for targeted reversal of his anticoagulation?

• Idarucizumab

• Andexanet alfa

• Protamine sulfate

• Fresh Frozen Plasma (FFP)

Answer explanation

Idarucizumab is a humanized monoclonal antibody fragment specifically designed to bind to dabigatran and its acylglucuronide metabolites with high affinity, rapidly neutralizing their anticoagulant effect.

Which of the following SSRIs has a pharmacologically active metabolite with a substantially long half-life, requiring a washout period of up to 5 weeks before safely initiating a monoamine oxidase inhibitor (MAOI)?

•  Fluoxetine

• Fluvoxamine

• Escitalopram

• Venlafaxine

Answer explanation

Fluoxetine's active metabolite, norfluoxetine, has an exceptionally long half-life (7–15 days), mandating a prolonged washout period to prevent the life-threatening risk of serotonin syndrome when switching to an MAOI.

Which of the following pharmacodynamic properties is the primary mechanism that differentiates aripiprazole’s side effect profile, particularly its lower incidence of extrapyramidal symptoms (EPS) and hyperprolactinemia, from other atypical antipsychotics?

• Partial agonism at dopamine D2 receptors

• High-affinity antagonism of serotonin 5-HT2A receptors

• Potent antagonism at histaminic H1 receptors

• Irreversible binding to muscarinic M1 receptors

Answer explanation

Aripiprazole’s unique mechanism as a D2 partial agonist allows it to act as a "dopamine stabilizer," reducing dopamine activity in hyperdopaminergic states and increasing it in hypodopaminergic states, minimizing EPS and hyperprolactinemia.

Among the extrapyramidal syndromes induced by dopamine receptor blocking agents, which of the following is considered the most frequently encountered clinical manifestation, and what is its indicated first-line treatment?

• Akathisia - Propranolol

• Acute Dystonia - Benztropine

  
  

• Tardive Dyskinesia - Valbenazine

• Neuroleptic Malignant Syndrome - Dantrolene

Answer explanation

Akathisia, a subjective feeling of inner restlessness and a compelling urge to move, is the most common extrapyramidal symptom. Propranolol is the established first-line therapy for managing this distressing side effect

A 42-year-old female with a history of bipolar I disorder presents for medication management. She is concerned about significant weight gain experienced with previous mood stabilizers. Her current BMI is 32 kg/m ². Which of the following agents offers a therapeutic advantage by addressing both her psychiatric condition and her metabolic concern?

• Topiramate

• Valproate

• Carbamazepine

• Gabapentin

Answer explanation

Topiramate is indicated for bipolar disorder and has a known side effect of weight loss. This makes it a uniquely suitable option for a patient with bipolar disorder and comorbid obesity or concerns about weight gain.

A 7-month-old infant diagnosed with infantile spasms was started on a new anti-epileptic drug. During a routine ophthalmologic follow-up several months later, significant bilateral concentric visual field constriction is noted. Which of the following medications is the most likely cause of this finding?

• Vigabatrin

• Cannabidiol

• Topiramate

• Lamotrigine

Answer explanation

Vigabatrin is a highly effective treatment for infantile spasms but is well-known for causing irreversible, bilateral concentric visual field constriction, requiring close ophthalmologic monitoring.

A 16-year-old female with a known history of juvenile myoclonic epilepsy (JME) is managed on monotherapy. Her generalized tonic-clonic seizures are well-controlled, but she continues to have several daily episodes of brief staring spells, confirmed as absence seizures on EEG. Which of the following mechanisms of her current medication is primarily responsible for targeting these absence seizures?

• Blockade of T-type calcium channels

•  Antagonism of NMDA receptors

• Inhibition of GABA transaminase

• Enhancement of slow inactivation of voltage-gated sodium channels

Answer explanation

Valproate is a first-line agent for JME. Its efficacy against absence seizures is primarily attributed to the inhibition of low-threshold T-type calcium channels in thalamic neurons, which disrupts the rhythmic discharges underlying these seizures

A 45-year-old male with refractory focal epilepsy is experiencing significant ataxia and diplopia on high-dose carbamazepine. An add-on therapy is considered that targets voltage-gated sodium channels via a distinct mechanism involving the enhancement of slow inactivation, rather than fast inactivation. Which of the following agents is the most appropriate choice?

•  Lacosamide

• Rufinamide

• Felbamate

• Ethosuximide

  
  

Answer explanation

 Lacosamide selectively enhances the slow inactivation of voltage-gated sodium channels, a mechanism distinct from traditional sodium channel blockers like carbamazepine, which primarily affect fast inactivation. This provides an alternative sodium channel-based therapeutic approach.

A 34-year-old female with a 5-year history of relapsing-remitting multiple sclerosis (RRMS), maintained on glatiramer acetate, presents to the emergency department with a 72-hour history of rapidly progressing vertigo, dysarthria, and new-onset ataxia, significantly impairing her ability to ambulate. An urgent MRI of the brain reveals a new, large, gadolinium-enhancing lesion in the cerebellum. Which of the following is the most appropriate immediate pharmacotherapeutic intervention?

• Intravenous methylprednisolone

• Initiation of subcutaneous interferon-beta

  
  

• Plasma exchange (PLEX)

• Oral baclofen

Answer explanation

High-dose intravenous corticosteroids, such as methylprednisolone, are the first-line treatment for acute MS relapses. They reduce inflammation and edema at the site of demyelination, accelerating functional recovery from the acute attack.

A 68-year-old male with a 10-year history of Parkinson's disease, managed effectively with Levodopa/Carbidopa, presents with new, distressing choreiform movements of his upper body and trunk. These movements are most pronounced approximately one hour after each dose. His neurologist identifies these as peak-dose dyskinesias. Which adjunctive medication would be most appropriate to specifically target this complication?

• Amantadine

• Selegiline

• Benztropine

• Entacapone

Answer explanation

Amantadine is the most appropriate choice as it possesses N-methyl-D-aspartate (NMDA) receptor antagonist properties. This mechanism is particularly effective in reducing the severity of levodopa-induced dyskinesias without compromising the antiparkinsonian effects of levodopa.