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  • Question 1 - Which of the following physical findings is least typical on a patient with...

    Incorrect

    • Which of the following physical findings is least typical on a patient with multiple sclerosis?

      Your Answer: Patellar clonus

      Correct Answer: Decreased tone

      Explanation:

      Attacks or exacerbations of multiple sclerosis (MS) are characterized by symptoms that reflect central nervous system (CNS) involvement, hence upper motor neuron symptoms are seen.

    • This question is part of the following fields:

      • Nervous System
      14.6
      Seconds

  • Question 2 - A gentleman arrives at the renal clinic for review. He has long standing...

    Correct

    • A gentleman arrives at the renal clinic for review. He has long standing chronic renal failure and is unfortunately suffering from metabolic bone disease. His GP has asked for an explanation of the causes and features of metabolic bone disease.

      Which of the following best describes the biochemical changes involved?

      Your Answer: Phosphate excretion is decreased, parathyroid hormone levels are increased and 1,25-OH vitamin D levels are decreased

      Explanation:

      The patient’s chronic renal failure causes decreased renal hydroxylation of vitamin D which leads to decreased calcium absorption in the gut. Simultaneously, there is also decreased renal excretion of phosphate, and this combination of factors results in increased PTH levels.

    • This question is part of the following fields:

      • Renal System
      21.8
      Seconds

  • Question 3 - A 34-year-old diabetic male is undergoing contrast radiography. What should you do to...

    Correct

    • A 34-year-old diabetic male is undergoing contrast radiography. What should you do to make sure that renal damage due to the contrast dye is prevented?

      Your Answer: Plenty of fluids

      Explanation:

      The risk of kidney damage during this procedure is greatly increased for a diabetic patient. It is therefore important that plenty of fluids are given to prevent dehydration and therefore damage to the kidneys.

    • This question is part of the following fields:

      • Renal System
      13.9
      Seconds

  • Question 4 - A 22 year-old university graduate presented with progressive unsteadiness during walking over the...

    Correct

    • A 22 year-old university graduate presented with progressive unsteadiness during walking over the last year. She had been otherwise healthy apart from recent difficulty hearing her lecturer in classes. She took no prescription medication but had occasionally taken cocaine during her first year of college. She also admits to drinking up to 30 units of alcohol per week and smoked 10 cigarettes per day. Her parents were both well, but her father's sister had problems with walking before she died. Examination reveals normal tone and power throughout all four limbs. Reflexes were normal in the upper limbs but decreased at the knees and absent at the ankles. Coordination was normal in all four limbs but her gait was ataxic. Sensation in the upper limbs was normal but decreased vibratory sensation and proprioception was noted to the ankles bilaterally. What is the most likely diagnosis?

      Your Answer: Friedreich's ataxia

      Explanation:

      Friedreich’s ataxia is an autosomal recessive disorder that usually begins before the end of the teens. It has an estimated prevalence in Europe of 1 in 50,000 and life expectancy is around 40-50 years. Neurological features include a progressive ataxia, cerebellar dysarthria, lower limb areflexia, decreased vibratory sensation and proprioception, and pyramidal weakness. Pes cavus and scoliosis are also both seen. Cardiomyopathy occurs in over 70% of cases. Less common features include optic atrophic, diabetes mellitus, and deafness.

    • This question is part of the following fields:

      • Nervous System
      2030
      Seconds

  • Question 5 - A 72-year-old male presents complaining of having intermittent trouble with swallowing. He has...

    Incorrect

    • A 72-year-old male presents complaining of having intermittent trouble with swallowing. He has also been regurgitating stale food material. He sometimes wakes up in the middle of the night feeling like he is suffocating. Choose the most likely diagnosis.

      Your Answer:

      Correct Answer: Pharyngeal pouch

      Explanation:

      In benign stricture, oesophageal carcinoma, and systemic sclerosis, there is persistent dysphagia (rather than intermittent). In oesophageal spasm, there is no regurgitation of stale food material. The symptoms described are consistent with pharyngeal pouch.

    • This question is part of the following fields:

      • Gastrointestinal System
      0
      Seconds

  • Question 6 - What is the mechanism of action of sildenafil citrate? ...

    Incorrect

    • What is the mechanism of action of sildenafil citrate?

      Your Answer:

      Correct Answer: Inhibition of phosphodiesterase V

      Explanation:

      Sildenafil citrate (Viagra) is the first oral drug to be widely approved for the treatment of erectile dysfunction.
      It is a potent and selective inhibitor of type-V phosphodiesterase, the primary form of the enzyme found in human penile erectile tissue, thereby preventing the breakdown of cyclic guanosine monophosphate (cGMP), the intracellular second messenger of nitric oxide.

      Uses:
      It is used for the treatment of erectile dysfunction, idiopathic pulmonary hypertension, premature ejaculation, high altitude illness, penile rehabilitation after radical prostatectomy, angina pectoris, and lower urinary tract symptoms.

      Adverse effects:
      Mild headache, flushing, dyspepsia, cyanopsia, back pain, and myalgias – due to a high concentration of PDE11 enzyme in skeletal muscle, which shows significant cross-reactivity with the use of tadalafil.
      It can also cause hypotension, dizziness, and rhinitis.

    • This question is part of the following fields:

      • Pharmacology
      0
      Seconds

  • Question 7 - Which of the following is most consistent with achondroplasia? ...

    Incorrect

    • Which of the following is most consistent with achondroplasia?

      Your Answer:

      Correct Answer: May be diagnosed radiologically at birth

      Explanation:

      Achondroplasia is the most common type of short-limb disproportionate dwarfism. A single gene mapped to the short arm of chromosome 4 (band 4p16.3) is responsible for achondroplasia and is transmitted as an autosomal dominant trait. All people with achondroplasia have a short stature.
      Characteristic features of achondroplasia include an average-size trunk, short arms and legs with particularly short upper arms and thighs, limited range of motion at the elbows, and an enlarged head (macrocephaly) with a prominent forehead. Fingers are typically short and the ring finger and middle finger may diverge, giving the hand a three-pronged (trident) appearance. People with achondroplasia are generally of normal intelligence.
      Examination of the infant after birth shows increased front-to-back head size. There may be signs of hydrocephalus. It may be diagnosed radiographically at birth, or becomes obvious within the first year with disparity between a large skull, normal trunk length and short limbs.

    • This question is part of the following fields:

      • Endocrine System & Metabolism
      0
      Seconds

  • Question 8 - A 30-year-old woman who works in a pharmacy comes to the clinic for...

    Incorrect

    • A 30-year-old woman who works in a pharmacy comes to the clinic for review. Over the past few months, she has lost increasing amounts of weight and has become increasingly anxious about palpitations, which occur mostly at night. Her TSH is <0.1 IU/l (0.5-4.5).
      On examination, her BP is 122/72 mmHg, her pulse is 92 and regular. You cannot palpate a goitre or any nodules on examination of her neck.
      Which of the following investigations can differentiate between self-administration of thyroid hormone and endogenous causes of thyrotoxicosis?

      Your Answer:

      Correct Answer: Radioactive uptake thyroid scan

      Explanation:

      Once thyrotoxicosis has been identified by laboratory values, the thyroid radio-iodine uptake and scan may be used to help distinguish the underlying aetiology. Thyroid radioiodine uptake is raised in Graves’ disease. It may be normal or raised in patients with a toxic multinodular goitre. It is very low or undetectable in thyrotoxicosis resulting from exogenous administration of thyroid hormone or the thyrotoxic phase of thyroiditis.

    • This question is part of the following fields:

      • Endocrine System & Metabolism
      0
      Seconds

  • Question 9 - A 46-year-old gentleman diagnosed with type 2 diabetes, hypertension, and proteinuria is started...

    Incorrect

    • A 46-year-old gentleman diagnosed with type 2 diabetes, hypertension, and proteinuria is started on Ramipril to prevent development of renal disease. He reports to his GP that he has developed a troublesome cough since starting the medication. He has no symptoms of lip swelling, wheeze and has no history of underlying respiratory disease.
       
      What increased chemical is thought to be the cause of his cough?

      Your Answer:

      Correct Answer: Bradykinin

      Explanation:

      Ramipril is an ACE inhibitor that blocks the conversion of angiotensin I to angiotensin II as well as preventing the breakdown of bradykinin, leading to blood vessel dilatation and decreased blood pressure. However, bradykinin also causes smooth muscles in the lungs to contract, so the build-up of bradykinin is thought to cause the dry cough that is a common side-effect in patients that are on ACE inhibitors.

    • This question is part of the following fields:

      • Renal System
      0
      Seconds

  • Question 10 - A 40-year-old lady who underwent a recent subtotal gastrectomy for peptic ulcer disease...

    Incorrect

    • A 40-year-old lady who underwent a recent subtotal gastrectomy for peptic ulcer disease has now developed anaemia with a haemoglobin of 6.4, tiredness, fatigue and loss of vibration sensation in both legs. What is the underlying cause of her symptoms?

      Your Answer:

      Correct Answer: B12 deficiency

      Explanation:

      Vit B12 needs intrinsic factor to be absorbed, which is secreted in the stomach. Its deficiency is characterised by macrocytic anaemia with peripheral neuropathy.

    • This question is part of the following fields:

      • Gastrointestinal System
      0
      Seconds

  • Question 11 - A 40-year-old female is suffering from chronic cough. Which of the following additional...

    Incorrect

    • A 40-year-old female is suffering from chronic cough. Which of the following additional symptoms will strongly indicate that she has asthma?

      Your Answer:

      Correct Answer: Symptoms in response to exercise

      Explanation:

      An attack of asthma is characterized by severe dyspnoea accompanied by wheezing. During an attack, the person experiences breathing difficulty during inspiration and expiration, but might feel completely well between attacks. An attack can be triggered by factors like cold, dry air, tobacco smoke, pollen, pet dander, as well as stressful situations like exercise. Dizziness, voice disturbances, and coryzal illness are not features of asthma.

    • This question is part of the following fields:

      • Respiratory System
      0
      Seconds

  • Question 12 - A 17-year-old girl presented with fever, headache and photophobia. Cerebrospinal fluid examination reveals:

    Opening...

    Incorrect

    • A 17-year-old girl presented with fever, headache and photophobia. Cerebrospinal fluid examination reveals:

      Opening pressure 260 mm H20 (50-180)
      Total protein 0.8 g/l (0.15-0.45)
      Glucose 4.2 mmol/l (3.3-4.4)
      White cell count 60 per ml (<5)
      Lymphocytes 90%
      Plasma glucose 6.4 mmol/l (3.0-6.0)

      Which of the following is the most likely diagnosis?

      Your Answer:

      Correct Answer: Viral meningitis

      Explanation:

      Normal cerebrospinal fluid (CSF) glucose together with lymphocytosis, an increased opening pressure and raised CSF protein are typical of a viral meningitis.

    • This question is part of the following fields:

      • Nervous System
      0
      Seconds

  • Question 13 - A 35-year-old female presented with complaints of earache and a high-grade fever. During...

    Incorrect

    • A 35-year-old female presented with complaints of earache and a high-grade fever. During examination, numerous small vesicles were found within the ear canal and her ear is very tender. Which one of the following organisms is most likely to be responsible for such a condition?

      Your Answer:

      Correct Answer: Herpes zoster

      Explanation:

      Herpes zoster is a viral disorder in which painful vesicular lesions are present in a specific dermatome area. High-grade fever may present as well due to infection. Varicella zoster, measles, herpes simplex and HIV do not present with tender lesions of a limited area.

    • This question is part of the following fields:

      • Infectious Diseases
      0
      Seconds

  • Question 14 - A 62-year-old male presented with loss of weight and tenesmus. Colonoscopy revealed rectal...

    Incorrect

    • A 62-year-old male presented with loss of weight and tenesmus. Colonoscopy revealed rectal carcinoma. All of the following are risk factors except:

      Your Answer:

      Correct Answer: High fibre diet

      Explanation:

    • This question is part of the following fields:

      • Emergency & Critical Care
      0
      Seconds

  • Question 15 - A 45-year-old male presents to the clinic complaining of vomiting and early morning...

    Incorrect

    • A 45-year-old male presents to the clinic complaining of vomiting and early morning headaches. CT scan of the brain shows multiple ring enhancing lesions. Which of the following is the cause of this finding?

      Your Answer:

      Correct Answer: Toxoplasmosis

      Explanation:

      Toxoplasmosis is a disease caused by the obligate intracellular parasite Toxoplasma gondii. Transmission occurs either through ingestion of cysts found, for example, in raw meat or cat faeces, or from mother to foetus through the placenta.
      The clinical presentation depends on the patient’s immune status: In immunocompetent individuals, 90% of cases are harmless and asymptomatic, with the remaining 10% displaying mild mononucleosis-like symptoms. In immunosuppressed patients (e.g., those who are HIV-positive), infection may result in cerebral toxoplasmosis (headache, confusion, focal neurologic deficits) or toxoplasma chorioretinitis (eye pain, reduced vision).
      Treatment is indicated for immunosuppressed patients, infected mothers, congenital toxoplasmosis, and immunocompetent patients with more severe symptoms. The treatment of choice is usually a combination of pyrimethamine, sulfadiazine, and leucovorin (folinic acid), with the exception of new infections during pregnancy, which are treated with spiramycin.

    • This question is part of the following fields:

      • Infectious Diseases
      0
      Seconds

  • Question 16 - A 35-year-old soldier presented with a painless, erythematous crusted plaque over the dorsum...

    Incorrect

    • A 35-year-old soldier presented with a painless, erythematous crusted plaque over the dorsum of his hand, after serving in a hilly area of Columbia for 2 months. The most likely diagnosis will be?

      Your Answer:

      Correct Answer: Leishmaniasis

      Explanation:

      The chief presentation in Leishmaniasis is a non healing, ulcerated, painless and non pruritic plaque, which does not respond to oral antibiotics. It can be classified into cutaneous and visceral forms and is caused by the sand fly. It is more prevalent in the hilly areas. Fusobacterium causes a tropical ulcer which is painful and shallow, while Troanasomiasis causes sleeping sickness.

    • This question is part of the following fields:

      • The Skin
      0
      Seconds

  • Question 17 - A baby is born to a mother who is known to have chronic...

    Incorrect

    • A baby is born to a mother who is known to have chronic hepatitis B. The mothers latest results are as follows:


      HBsAg Positive
      HBeAg Positive

      What is the most appropriate strategy for reducing the vertical transmission rate?

      Your Answer:

      Correct Answer: Give the newborn hepatitis B vaccine + hepatitis B immunoglobulin

      Explanation:

      The Green Book guidelines report in an active infection (HBeAg+ and HBsAg+) to give the vaccine as well as immunoglobulin. If antibodies are present it is not active infection (anti-Hbe) and then in that case only the vaccine, and no immunoglobulin, would be given. The presence of HBeAg means a person is infectious and can transmit to other people.

    • This question is part of the following fields:

      • Infectious Diseases
      0
      Seconds

  • Question 18 - Which of the following is not a recognised feature of methemoglobinemia? ...

    Incorrect

    • Which of the following is not a recognised feature of methemoglobinemia?

      Your Answer:

      Correct Answer: Decreased pO2 but normal oxygen saturation

      Explanation:

      Normal pO2 but decreased oxygen saturation is characteristic of methemoglobinemia.

      Methemoglobinemia is a rare condition in which the haemoglobin iron is in oxidized or ferric state (Fe3+) and cannot reversibly bind oxygen. Normally, the conversion of ferrous form of iron (Fe2+) to its ferric form (Fe3+) is regulated by NADH methaemoglobin reductase, which results in the reduction of methaemoglobin to haemoglobin. Disruption in the enzyme leads to increased methaemoglobin in the blood. There is tissue hypoxia as Fe3+ cannot bind oxygen, and hence the oxygen-haemoglobin dissociation curve is shifted to the left.

      Methemoglobinemia can occur due to congenital or acquired causes. Congenital causes include haemoglobin variants such as HbM and HbH, and deficiency of NADH methaemoglobin reductase. Acquired causes are drugs (e.g. sulphonamides, nitrates, dapsone, sodium nitroprusside, and primaquine) and chemicals (such as aniline dyes).

      The features of methemoglobinemia are cyanosis, dyspnoea, anxiety, headache, severe acidosis, arrhythmias, seizures, and loss of consciousness. Patients have normal pO2 but oxygen saturation is decreased. Moreover, presence of chocolate-brown coloured arterial blood (colour does not change with addition of O2) and brown urine also point towards the diagnosis of methemoglobinemia.

    • This question is part of the following fields:

      • Haematology & Oncology
      0
      Seconds

  • Question 19 - A 32-year-old complains of pain in her hands bilaterally. Which of the following...

    Incorrect

    • A 32-year-old complains of pain in her hands bilaterally. Which of the following symptoms would point towards an inflammatory joint disease such as rheumatoid arthritis?

      Your Answer:

      Correct Answer: Marked stiffness for more than an hour in the mornings

      Explanation:

      In rheumatoid arthritis (RA), clinical symptoms of joint stiffness, pain, and functional disability are commonly most severe in the early morning. These symptoms closely follow the circadian rhythm of the pro-inflammatory cytokine, interleukin (IL)-6. In RA, the increase in nocturnal anti-inflammatory cortisol secretion is insufficient to suppress ongoing inflammation, resulting in the morning symptoms characteristic of RA. Established diagnostic criteria for RA include prolonged morning stiffness that could last up to an hour. Loss of joint mobility, pain, malaise and swelling of finger joints are features that are not specific to rheumatoid arthritis, and are found in many other conditions.

    • This question is part of the following fields:

      • Musculoskeletal System
      0
      Seconds

  • Question 20 - A 70-year-old male patient with hypertension complains of acute urinary retention. He provides...

    Incorrect

    • A 70-year-old male patient with hypertension complains of acute urinary retention. He provides a history of urinary frequency for the past 18 months and has been taking Nifedipine and Propranolol for blood pressure control. Which of the following is the most probable cause for his acute presentation?

      Your Answer:

      Correct Answer: Drug induced

      Explanation:

      Calcium channel blockers decrease smooth-muscle contractility in the bladder and this can cause urinary retention.
      An enlarged prostate gland could be the reason if he gave a history of obstructive symptoms.
      Diabetes presents with polyuria.
      Bladder cancer commonly presents with painless haematuria.

    • This question is part of the following fields:

      • Renal System
      0
      Seconds

  • Question 21 - The family of a 10-year-old boy was advised to take the boy to...

    Incorrect

    • The family of a 10-year-old boy was advised to take the boy to see an oncologist, for suspected lymphoma. The boy had lymphadenopathy on presentation. His mother says that he's had a fever, night sweats and has experienced weight loss. The boy underwent a lymph node biopsy at the oncologist which suggests Burkitt's lymphoma. Which oncogene are you expecting to see after molecular testing?

      Your Answer:

      Correct Answer: c-MYC

      Explanation:

      Burkitt lymphoma is a germinal centre B-cell-derived cancer that was instrumental in the identification of MYC as an important human oncogene more than three decades ago. Recently, new genomics technologies have uncovered several additional oncogenic mechanisms that cooperate with MYC to create this highly aggressive cancer.

    • This question is part of the following fields:

      • Haematology & Oncology
      0
      Seconds

  • Question 22 - In chemotherapy, what is the rationale behind using combinations of chemotherapeutic agents rather...

    Incorrect

    • In chemotherapy, what is the rationale behind using combinations of chemotherapeutic agents rather than single agents?

      Your Answer:

      Correct Answer: Combination therapy decreases the chances of drug resistance developing

      Explanation:

      There are two main reasons for using combinations of chemotherapeutic agents rather than single agents. First, different drugs exert their effects through different mechanisms, therefore, carefully combining them will increase the number of tumour cells killed in each cycle as well as decrease their chances of developing drug resistance. Second, there may be an even greater effect with drugs that are synergistic.

    • This question is part of the following fields:

      • Haematology & Oncology
      0
      Seconds

  • Question 23 - Osteopetrosis occurs as a result of a defect in: ...

    Incorrect

    • Osteopetrosis occurs as a result of a defect in:

      Your Answer:

      Correct Answer: Osteoclast function

      Explanation:

      It is a metabolic bone disease caused by defective osteoclastic resorption of immature bone. Osteopetrosis is also known as marble bone disease. Osteoclasts are unable to adequately acidify bone matrix. Impaired bone resorption leads to overly dense bone that is more likely to fracture. It is usually treated with bone marrow transplant and high dose calcitriol.

    • This question is part of the following fields:

      • Musculoskeletal System
      0
      Seconds

  • Question 24 - Which among these medications does NOT cause gastric ulceration? ...

    Incorrect

    • Which among these medications does NOT cause gastric ulceration?

      Your Answer:

      Correct Answer: Misoprostol

      Explanation:

      Misoprostol is effective in preventing gastric ulceration since it is a prostaglandin analogue. Celecoxib, being a selective COX-2 inhibitor only elevates risk of ulceration as well as NSAIDs. Renal failure on the other hand results in elevated gastric acid after reducing the breakdown of gastrin.

    • This question is part of the following fields:

      • Gastrointestinal System
      0
      Seconds

  • Question 25 - A 71-year-old male got trapped under a cupboard for 4 hours which accidentally...

    Incorrect

    • A 71-year-old male got trapped under a cupboard for 4 hours which accidentally fell on his leg while he was moving his house. Which enzyme activity would you measure in this patient?

      Your Answer:

      Correct Answer: Creatinine kinase

      Explanation:

      Creatine kinase (CK) is an enzyme found in the heart, brain, skeletal muscle, and other tissues. Increased amounts of CK are released into the blood when there is muscle damage. This test measures the amount of creatine kinase in the blood.

    • This question is part of the following fields:

      • Musculoskeletal System
      0
      Seconds

  • Question 26 - A 30-year-old woman is hypertensive and complains of painless haematuria. Other examination results...

    Incorrect

    • A 30-year-old woman is hypertensive and complains of painless haematuria. Other examination results are unremarkable. What is the most likely diagnosis?

      Your Answer:

      Correct Answer: Polycystic kidneys

      Explanation:

      Renal ultrasound is utilized to confirm this condition. Although at a younger age, hypertension and haematuria that is not painful is already suggestive to the disease.

    • This question is part of the following fields:

      • Renal System
      0
      Seconds

  • Question 27 - A 3-year-old girl is brought to the clinic by her mother due to...

    Incorrect

    • A 3-year-old girl is brought to the clinic by her mother due to burning micturition, frequency and urgency. She is also experiencing some suprapubic tenderness. Which of the following investigations should be done initially?

      Your Answer:

      Correct Answer: Clean catch of urine for Culture &Sensitivity

      Explanation:

      Urine culture and sensitivity is used to diagnose a urinary tract infection (UTI). A mid-stream clean catch urine sample is the most common type of sample collected. It is important to follow the clean catch process to have accurate results from an uncontaminated sample. Urine cultures can also check for infections of the bladder or kidney.

    • This question is part of the following fields:

      • Renal System
      0
      Seconds

  • Question 28 - A 55-year-old woman diagnosed with type 2 diabetes presents with vomiting and diarrhoea...

    Incorrect

    • A 55-year-old woman diagnosed with type 2 diabetes presents with vomiting and diarrhoea after eating a meal of chicken and chips. She said her stool had small amounts of blood in. Campylobacter Jejuni was found on her stool culture exam. Which of the following is the most appropriate therapy?

      Your Answer:

      Correct Answer: IV fluids

      Explanation:

      Campylobacter is the most likely cause of diarrheal illness often due to undercooked meat being ingested. It is also a major cause of traveller’s diarrhoea. Sufficient fluid replacement and anti-emetics are indicated first followed by the antibiotic, Erythromycin although antibiotic treatment in adults is still in question. Ciprofloxacin and Tetracycline may also be effective.

    • This question is part of the following fields:

      • Infectious Diseases
      0
      Seconds

  • Question 29 - Impaired glucose tolerance is indicated by what glucose venous plasma level 2 hours...

    Incorrect

    • Impaired glucose tolerance is indicated by what glucose venous plasma level 2 hours after taking the OGTT test?

      Your Answer:

      Correct Answer: Between 7.8-11.0mmol/l

      Explanation:

      According to the criteria of the World Health Organization and the American Diabetes Association, impaired glucose tolerance is defined as:
      two-hour glucose levels of 140 to 199 mg per dL (7.8 to 11.0 mmol/l) on the 75-g oral glucose tolerance test.

    • This question is part of the following fields:

      • Endocrine System & Metabolism
      0
      Seconds

  • Question 30 - A 50-year-old hypertensive male on phenytoin and clobazam for partial seizures is also...

    Incorrect

    • A 50-year-old hypertensive male on phenytoin and clobazam for partial seizures is also taking lisinopril, cimetidine, sucralfate, and allopurinol. The last few drugs were added recently. He now presents with ataxia, slurred speech, and blurred vision.
      Which recently added drug is most likely to be the cause of his latest symptoms?

      Your Answer:

      Correct Answer: Cimetidine

      Explanation:

      The symptoms of ataxia, slurred speech and blurred vision are all suggestive of phenytoin toxicity. Cimetidine increases the efficacy of phenytoin by reducing its hepatic metabolism.

      Phenytoin has a narrow therapeutic index (10-20 mg/L) and its levels are monitored by measuring the total phenytoin concentration.
      Cimetidine is an H2 receptor antagonist used in the treatment of peptic ulcers. It acts by decreasing gastric acid secretion.
      Cimetidine also has an inhibitory effect on several isoforms of the cytochrome enzyme system including the CYP450 enzymatic pathway. Phenytoin is metabolized by the same cytochrome P450 enzyme system in the liver.
      Thus, the simultaneous administration of both these medications leads to an inhibition of phenytoin metabolism and thus increases its circulating levels leading to phenytoin toxicity.

    • This question is part of the following fields:

      • Pharmacology
      0
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Nervous System (1/2) 50%
Renal System (2/2) 100%
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