A 42-year-old woman who has taken clonazepam daily for panic disorder for 6 years is brought to casualty drowsy after swallowing 20 of her tablets. She rouses to voice, with a respiratory rate of 14/min, SpO2 96% on room air and a normal ECG. The intern wants to give IV flumazenil to wake her. What is the main danger of doing so?

Precipitated withdrawal with seizures

Toxicology antidotes, pharmacovigilance and drugs in pregnancy

23 NEET-PG practice questions on Toxicology antidotes, pharmacovigilance and drugs in pregnancy, part of Pharmacology. The first 23 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A 24-year-old woman with juvenile myoclonic epilepsy is brought to casualty in Jaipur 4 hours after swallowing 30 tablets of sodium valproate 500 mg after a family quarrel. She is drowsy but protecting her airway, BP is 110/70 mmHg, and her blood ammonia is 160 µmol/L (normal below 50 µmol/L). Liver enzymes and bilirubin are normal. Which specific treatment should be started?
1. AIntravenous fomepizole
2. BIntravenous flumazenil
3. CIntravenous L-carnitine
4. DIntravenous acetylcysteine
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Answer: C · Intravenous L-carnitine
Valproate overdose causes CNS depression, and valproate-induced hyperammonaemia can cause encephalopathy even when liver function is normal. Valproate depletes carnitine, which carries long-chain fatty acids into mitochondria, and its metabolites impair the urea cycle, so ammonia rises. IV L-carnitine replaces carnitine and is advised in valproate overdose with hyperammonaemia, encephalopathy or liver injury, along with supportive care. Haemodialysis is considered for very high levels with coma or shock.
- A: Fomepizole blocks alcohol dehydrogenase in methanol and ethylene glycol poisoning.
- B: Flumazenil reverses benzodiazepines and may provoke seizures in a person with epilepsy.
- D: Acetylcysteine is the antidote for paracetamol poisoning.
Question 2 · Medium
A district hospital drug and therapeutics committee in Tamil Nadu is revising its formulary in line with the National List of Essential Medicines (NLEM). The pharmacologist presents four statements: 1. Medicines are chosen mainly because they are the cheapest available. 2. The essential medicines concept comes from WHO, which issued its first Model List in 1977. 3. Medicines on the NLEM are price-controlled by the NPPA under the Drugs (Prices Control) Order. 4. Medicines on the list are named by their generic names. Which statements are correct?
1. A2, 3 and 4 only
2. B2 and 3 only
3. C1, 2 and 4 only
4. D1 and 4 only
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Answer: A · 2, 3 and 4 only
Statements 2, 3 and 4 are correct. Essential medicines are those that meet the priority health needs of the population, and they are chosen for public health relevance, evidence of efficacy and safety, and comparative cost-effectiveness, not simply the lowest price. WHO published its first Model List of Essential Medicines in 1977, and India's NLEM, listed by generic name, forms the schedule of medicines whose ceiling prices the National Pharmaceutical Pricing Authority fixes under the Drugs (Prices Control) Order. Hospitals use the list to guide procurement and rational prescribing.
- B: Leaves out generic naming, which is correct.
- C: Includes cost alone as the basis for selection and leaves out price control.
- D: Includes cost alone and leaves out WHO's model list and price control.
Question 3 · Medium
A 42-year-old woman who has taken clonazepam daily for panic disorder for 6 years is brought to casualty drowsy after swallowing 20 of her tablets. She rouses to voice, with a respiratory rate of 14/min, SpO2 96% on room air and a normal ECG. The intern wants to give IV flumazenil to wake her. What is the main danger of doing so?
1. APrecipitated withdrawal with seizures
2. BSerotonin syndrome
3. CAcute dystonic reaction
4. DMalignant hyperthermia
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Answer: A · Precipitated withdrawal with seizures
Flumazenil is a competitive antagonist at the benzodiazepine site of the GABA-A receptor. In someone dependent on long-term benzodiazepines it can precipitate abrupt withdrawal with agitation and seizures, and it can unmask seizures when a proconvulsant such as a tricyclic antidepressant has also been taken. A pure benzodiazepine overdose with protected breathing rarely kills, so supportive care and observation are enough here. Flumazenil is mainly used to reverse sedation given for procedures in benzodiazepine-naive patients, and because it is short-acting, sedation may return.
- B: Serotonin syndrome follows combinations of serotonergic drugs.
- C: Acute dystonia follows dopamine blockers such as metoclopramide.
- D: Malignant hyperthermia follows volatile anaesthetics or succinylcholine.
Question 4 · Medium
A 4-year-old girl whose family recycles old car batteries at home in a Delhi slum has abdominal colic, constipation, irritability and poor appetite. Hb is 8.9 g/dL with microcytic red cells showing basophilic stippling, and her blood lead level is 58 µg/dL. She is alert with no signs of encephalopathy. Besides removing her from exposure, which treatment is most appropriate?
1. AOral deferiprone
2. BOral succimer (DMSA)
3. CIntravenous desferrioxamine
4. DRepeat blood lead in 3 months
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Answer: B · Oral succimer (DMSA)
Lead inhibits delta-aminolevulinic acid dehydratase and ferrochelatase, causing anaemia with basophilic stippling, and damages the developing brain even at low levels. A child with a blood lead of 45-69 µg/dL and no encephalopathy is chelated with oral succimer (dimercaptosuccinic acid), whereas encephalopathy or a level of 70 µg/dL or more calls for dimercaprol followed by calcium disodium EDTA in hospital. Removing the source, correcting iron deficiency and testing her siblings matter as much as the chelator.
- A: Deferiprone is an oral iron chelator, not a lead antidote.
- C: Desferrioxamine chelates iron and aluminium, not lead.
- D: A level of 58 µg/dL with symptoms needs chelation now, not observation.
Question 5 · Medium
A 25-year-old woman at 20 weeks of pregnancy has a mucopurulent cervical discharge at her antenatal visit, and a nucleic acid amplification test on the cervical swab is positive for Chlamydia trachomatis. Which drug is preferred for her?
1. AMetronidazole
2. BLevofloxacin
3. CDoxycycline
4. DAzithromycin
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Answer: D · Azithromycin
Azithromycin as a single oral dose is the preferred treatment for chlamydial infection in pregnancy; amoxicillin is an alternative. Tetracyclines such as doxycycline are avoided because they cross the placenta and bind calcium in developing teeth and bones, causing permanent yellow-brown staining, enamel hypoplasia and impaired bone growth. Fluoroquinolones are also avoided in pregnancy. Her partner must be treated, and a test of cure is advised in pregnancy because untreated infection can cause neonatal conjunctivitis and pneumonia.
- A: Metronidazole treats trichomonas and bacterial vaginosis, not chlamydia.
- B: Fluoroquinolones are avoided in pregnancy.
- C: Doxycycline is avoided in pregnancy because it stains fetal teeth and affects bone.
Question 6 · Easy
Thalidomide is still prescribed in India for erythema nodosum leprosum and multiple myeloma, under strict pregnancy prevention. Taken in early pregnancy, which characteristic birth defect does it cause?
1. ACleft lip and palate
2. BEbstein anomaly
3. CSpina bifida
4. DPhocomelia
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Question 7 · Hard
A 34-year-old man is pulled out of a fire in a closed godown full of plastic goods and foam furniture. He is confused and then has a seizure. BP is 80/50 mmHg, SpO2 on the pulse oximeter is 97% on high-flow oxygen, serum lactate is 11 mmol/L and carboxyhaemoglobin is 18%. Besides 100% oxygen, which antidote is most appropriate?
1. AInhaled amyl nitrite
2. BIntravenous sodium nitrite
3. CIntravenous methylene blue
4. DIntravenous hydroxocobalamin
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Question 8 · Easy
A junior resident in a medical college in Lucknow sees a man who developed a widespread rash with fever two weeks after starting carbamazepine. She fills in the Suspected Adverse Drug Reaction Reporting Form and sends it to the college's ADR monitoring centre. Under the Pharmacovigilance Programme of India, which body houses the National Coordination Centre?
1. ANational Pharmaceutical Pricing Authority
2. BIndian Council of Medical Research
3. CNational Centre for Disease Control
4. DIndian Pharmacopoeia Commission
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Question 9 · Medium
A 19-year-old girl on treatment for pulmonary TB is brought to casualty an hour after swallowing 25 tablets of isoniazid 300 mg after a quarrel. She has had three generalised seizures that did not stop with two doses of IV lorazepam. ABG: pH 7.06, HCO3- 8 mmol/L, lactate 9 mmol/L. Which specific antidote should be given?
1. AIntravenous pyridoxine
2. BIntravenous thiamine
3. CIntravenous phenytoin
4. DIntravenous flumazenil
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Question 10 · Hard
A 30-year-old man develops a generalised itchy maculopapular rash on the fifth day of amoxicillin for sinusitis. He takes no other medicine, has no fever, lymph nodes or other features of a viral illness, and has had no previous drug reactions. The rash fades within a week of stopping amoxicillin, and he is not given the drug again. Using the WHO-UMC causality system, how should this reaction be graded when it is reported to PvPI?
1. AUnlikely
2. BCertain
3. CProbable/likely
4. DPossible
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Question 11 · Medium
A 30-year-old paddy farmer in Tamil Nadu is bitten on the foot by a snake that his companions identify as a cobra. Two hours later he has bilateral ptosis, difficulty swallowing and a weak voice, with no bleeding and a normal 20-minute whole blood clotting test. Polyvalent anti-snake venom has been started. Which drug is given with it to improve neuromuscular transmission?
1. ANeostigmine with atropine
2. BIntravenous magnesium sulphate
3. CPralidoxime with atropine
4. DIntravenous calcium gluconate
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Question 12 · Easy
A newborn has a flat, underdeveloped nasal bridge and stippled epiphyses on X-ray. Which drug taken by the mother in early pregnancy most likely caused this?
1. AEnoxaparin
2. BWarfarin
3. CPhenytoin
4. DMethyldopa
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Question 13 · Hard
Platelet count fell from 2.6 lakh to 85,000/µL on the seventh day of unfractionated heparin given for deep vein thrombosis after hip surgery, and the leg swelling has extended to the thigh. A 4T score is 7 and an anti-PF4 antibody assay is strongly positive. Heparin has been stopped. Which anticoagulant should be started now?
1. AArgatroban
2. BPlatelet transfusion with heparin
3. CWarfarin
4. DEnoxaparin
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Question 14 · Medium
During haemodialysis, an inadvertent extra bolus of unfractionated heparin is given to a patient, and he starts bleeding from the fistula site and gums; aPTT is more than three times the control. He weighs 70 kg and received 5,000 units extra about 20 minutes ago; his platelet count is normal. Which drug neutralises heparin, and how?
1. ATranexamic acid, which blocks plasminogen activation
2. BIdarucizumab, which binds the drug in plasma
3. CProtamine sulphate, a basic protein that binds acidic heparin
4. DVitamin K1, which restores clotting factor synthesis
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Question 15 · Medium
A resident in dermatology sees Stevens-Johnson syndrome three weeks after carbamazepine was started. Consider these statements about reporting it under PvPI: 1. Any healthcare professional may report it. 2. Certainty of causality is not needed before reporting. 3. Patients may also report reactions directly. 4. Only reactions not already listed in the package insert should be reported. Which statements are correct?
1. A1, 2, 3 and 4
2. B2, 3 and 4 only
3. C1 and 2 only
4. D1, 2 and 3 only
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Question 16 · Hard
Three weeks into multibacillary leprosy treatment with dapsone, rifampicin and clofazimine, a man from Odisha has breathlessness, headache and slate-grey cyanosis. SpO2 reads 85% despite oxygen, but PaO2 is 98 mmHg; methaemoglobin is 24%. His haemoglobin has also fallen from 12.8 to 9.1 g/dL with bite cells on the smear, and a G6PD screen is deficient. Dapsone has been stopped. He weighs 48 kg, takes dapsone 100 mg daily, and comes from a community where G6PD deficiency is common. He is alert, with BP 110/70 mmHg and a pulse of 112/min. What is the most appropriate further treatment?
1. AIntravenous methylene blue 1-2 mg/kg
2. BHigh-dose ascorbic acid, with exchange transfusion if severe
3. CIntravenous sodium thiosulphate
4. DHyperbaric oxygen as the first measure
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Question 17 · Easy
Paracetamol level at 4 hours lies above the treatment line in a student who swallowed 40 tablets of 500 mg. Which antidote should be started?
1. AOral activated charcoal alone
2. BIntravenous flumazenil
3. CIntravenous fomepizole
4. DIntravenous N-acetylcysteine
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Question 18 · Medium
As the pharmacy in-charge of a district hospital, you note that a commonly used antibiotic has just been added to the National List of Essential Medicines. The drug was previously sold at widely varying prices by different manufacturers. The hospital buys it through the state medical services corporation. What is the direct regulatory consequence of its inclusion in India?
1. AIt becomes available only on a specialist prescription
2. BIt is removed from over-the-counter sale
3. CNPPA fixes a ceiling price for its formulations
4. DIts manufacture moves to public sector units only
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Question 19 · Medium
In the casualty, a farmer who drank an organophosphate pesticide two hours ago has pinpoint pupils, profuse sweating, bronchorrhoea with crackles over both lungs and a pulse of 52/min. Doubling doses of IV atropine are being given every 5 minutes. Oxygen and pralidoxime have also been started, and an ICU bed is being arranged. Which finding best shows that enough atropine has been given?
1. AA clear chest on auscultation
2. BPulse above 140/min
3. CReturn of normal muscle power
4. DPupils dilated beyond 6 mm in both eyes
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Question 20 · Medium
Planning a pregnancy next year, a young woman with juvenile myoclonic epilepsy has been seizure-free for three years on sodium valproate 1,000 mg daily. She asks the neurology clinic what she should do. She has no other illness, takes no other drugs, and her last EEG was normal. What is the best advice?
1. AStop all antiepileptics once pregnant
2. BContinue valproate and start folic acid
3. CSwitch to carbamazepine before conception
4. DSwitch to levetiracetam before conception
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Question 21 · Medium
On digoxin 0.25 mg daily for atrial fibrillation, an elderly widow with worsening kidney function presents with vomiting, yellow-tinged vision and a pulse of 38/min with complete heart block. Serum potassium is 6.1 mmol/L (normal 3.5-5.0) and the digoxin level is 4.2 ng/mL (therapeutic 0.5-0.9). Atropine has not improved the rate. Which treatment is most appropriate?
1. AIntravenous potassium chloride
2. BIntravenous lignocaine infusion
3. CDigoxin-specific Fab fragments
4. DIntravenous calcium gluconate
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Question 22 · Medium
After an argument, a college student reaches the casualty 8 hours after swallowing paracetamol tablets; she is well except for nausea. Her vitals are stable, liver enzymes are normal and she is not pregnant. The plasma level is plotted on the chart shown. What is the next step?
Figure: MedExams
1. ARepeat the level after 4 hours
2. BStart intravenous acetylcysteine now
3. CDischarge with psychiatric follow-up
4. DGive activated charcoal alone
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Question 23 · Hard
Three weeks into MB-MDT for leprosy at a district hospital, a young man develops breathlessness and slate-grey cyanosis. Pulse oximetry reads 85% despite oxygen, while arterial PaO2 is 102 mm Hg; the blood is chocolate-brown and methaemoglobin is 32%. Hb has fallen from 12.8 to 9.6 g/dL with bite cells on the smear, and G6PD screening is deficient. Which treatment is most appropriate?
1. AHigh-dose intravenous ascorbic acid
2. BIntravenous sodium thiosulfate
3. CIntravenous methylene blue 1 mg/kg
4. DIntravenous hydroxocobalamin
Answer and explanation in LearnFree account

Toxicology antidotes, pharmacovigilance and drugs in pregnancy

A 25-year-old woman at 20 weeks of pregnancy has a mucopurulent cervical discharge at her antenatal visit, and a nucleic acid amplification test on the cervical swab is positive for Chlamydia trachomatis. Which drug is preferred for her?

Thalidomide is still prescribed in India for erythema nodosum leprosum and multiple myeloma, under strict pregnancy prevention. Taken in early pregnancy, which characteristic birth defect does it cause?

A newborn has a flat, underdeveloped nasal bridge and stippled epiphyses on X-ray. Which drug taken by the mother in early pregnancy most likely caused this?

Paracetamol level at 4 hours lies above the treatment line in a student who swallowed 40 tablets of 500 mg. Which antidote should be started?

After an argument, a college student reaches the casualty 8 hours after swallowing paracetamol tablets; she is well except for nausea. Her vitals are stable, liver enzymes are normal and she is not pregnant. The plasma level is plotted on the chart shown. What is the next step?