Pediatric Dosing Principles — MCQs
Pseudotumor Cerebri in Infants is seen with?
Which of the following drugs can cause cartilage damage in children?
What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?
A 70 kg man was given a drug with a dose of 100 mg/kg body weight, twice daily. The half-life (t1/2) is 10 hours, the plasma concentration is 1.9 mg/mL, and the clearance is unknown. What is the clearance of this drug?
A pediatric patient presents with a 45-minute history of continuous convulsions. The senior resident (SR) recommends IV lorazepam, but the junior resident (JR) is unable to secure IV access. What is the next best step in management?
EDD ( Expected Date of Delivery) is calculated by:
2 year old child with length 85cm and weight of 11kg was found to have serum urea of 49mg/dl, serum creatinine 2mg/dl What is the estimated GFR of this child, as per Schwartz formula?
For the treatment of kala-azar, the daily dose of miltefosine in a 3-year-old child who weighs 15 kg is
One year old male child with cat's reflex and raised IOP. What is the most likely diagnosis?
Treatment of choice for antrochoanal polyp in a 10-year-old child-
Pediatric Dosing Principles Indian Medical PG Practice Questions and MCQs
Question 1: Pseudotumor Cerebri in Infants is seen with?
- A. Aminoglycosides
- B. Tetracyclines (Correct Answer)
- C. Macrolides
- D. NSAIDs
Explanation: ***Tetracyclines***- **Tetracyclines**, particularly in infants, are a known cause of **pseudotumor cerebri**, also known as **idiopathic intracranial hypertension (IIH)**. - This condition involves increased **intracranial pressure (ICP)**, leading to symptoms like **headache**, **visual disturbances**, and **papilledema**. *Aminoglycosides*- **Aminoglycosides** are primarily associated with **ototoxicity** (hearing loss) and **nephrotoxicity** (kidney damage) [1]. - They are not typically linked to the development of **pseudotumor cerebri**. *NSAIDS*- **NSAIDs** (Nonsteroidal Anti-inflammatory Drugs) are more commonly associated with **gastrointestinal ulcers** and **renal impairment**. - While they can have neurological side effects in some cases, **pseudotumor cerebri** is not a characteristic or common adverse effect. *Macrolides*- **Macrolides** like erythromycin or azithromycin are generally well-tolerated and are primarily associated with **gastrointestinal upset** and **QT prolongation**. - There is no significant evidence linking **macrolide use** to the development of **pseudotumor cerebri**.
Question 2: Which of the following drugs can cause cartilage damage in children?
- A. Cotrimoxazole and other sulfonamides
- B. Penicillin and other beta-lactams
- C. Metronidazole and other nitroimidazoles
- D. Ciprofloxacin and other fluoroquinolones (Correct Answer)
Explanation: ***Ciprofloxacin and other fluoroquinolones*** - Fluoroquinolones, including ciprofloxacin, are known to cause **arthropathy** (joint disease) and **cartilage damage** in growing children and adolescents [1]. - This adverse effect has limited their use in pediatric populations, typically reserved for severe infections where other effective and safer alternatives are unavailable [1]. *Cotrimoxazole and other sulfonamides* - Sulfonamides are primarily associated with adverse effects like **hypersensitivity reactions** (e.g., Stevens-Johnson syndrome), **bone marrow suppression**, and **crystalluria**. - They are not typically linked to cartilage damage in children. *Penicillin and other beta-lactams* - Penicillins and other beta-lactam antibiotics are generally considered **safe in children** and are a common choice for pediatric infections. - Their primary adverse effects are hypersensitivity reactions, such as **rashes** or **anaphylaxis**, and gastrointestinal disturbances, not cartilage damage. *Metronidazole and other nitroimidazoles* - Metronidazole's main adverse effects include **gastrointestinal upset**, **metallic taste**, and **neurological symptoms** (e.g., peripheral neuropathy, seizures with high doses). - There is no known association between metronidazole and cartilage damage in children.
Question 3: What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?
- A. First pass kinetics
- B. First order kinetics
- C. Zero order kinetics (Correct Answer)
- D. Second order kinetics
Explanation: ***Zero order kinetics*** - This mechanism occurs when the **metabolic enzymes become saturated at high drug concentrations**, leading to a constant amount (not a constant percentage) of drug being eliminated per unit time. - Alcohol, aspirin, and phenytoin are examples of drugs that exhibit **saturable metabolism**, transitioning from first-order to zero-order kinetics at higher doses. *First pass kinetics* - This describes the **metabolism of a drug by the liver or gut wall enzymes before it reaches systemic circulation** after oral administration. - While relevant to the oral bioavailability of these drugs, it does not describe the specific mechanism of elimination at high doses. *First order kinetics* - In this mechanism, a **constant fraction or percentage of the drug is eliminated per unit of time**, meaning the rate of elimination is directly proportional to the drug concentration. - Most drugs follow first-order kinetics at therapeutic doses because metabolizing enzymes are not saturated. *Second order kinetics* - This is a **less common pharmacokinetic model** where the rate of elimination is proportional to the square of the drug concentration or involves two reactants. - It does not typically describe the common elimination patterns of most drugs, including alcohol, aspirin, and phenytoin.
Question 4: A 70 kg man was given a drug with a dose of 100 mg/kg body weight, twice daily. The half-life (t1/2) is 10 hours, the plasma concentration is 1.9 mg/mL, and the clearance is unknown. What is the clearance of this drug?
- A. 20 liter/hr
- B. K is 0.0693
- C. 0.22 L/hr (Correct Answer)
- D. 0.02 L/hr
Explanation: ***0.22 L/hr*** - To calculate clearance at steady state, we use the formula: **Clearance (Cl) = Dose Rate / Css** (steady-state plasma concentration). - **Dose rate calculation**: 100 mg/kg × 70 kg × 2 doses/day = 14,000 mg/day = 583.33 mg/hr - **Converting plasma concentration**: 1.9 mg/mL = 1900 mg/L - **Clearance calculation**: Cl = 583.33 mg/hr ÷ 1900 mg/L = **0.307 L/hr** - **Note**: The calculated value (0.307 L/hr) does not exactly match any option. The marked answer (0.22 L/hr) is the closest approximation among the given choices. This discrepancy may arise from rounding in the original question parameters or implicit assumptions about bioavailability/volume of distribution. *0.02 L/hr* - This value is approximately 15 times lower than the calculated clearance. - Such low clearance would result in much higher plasma concentrations or require significantly lower dosing. *20 liter/hr* - This clearance is approximately 65 times higher than calculated, representing an unrealistically high value for this scenario. - Such high clearance would result in very low plasma concentrations unless extremely high doses were administered. *K is 0.0693* - This represents the **elimination rate constant (k)**, calculated as k = 0.693/t1/2 = 0.693/10 hr = 0.0693 hr⁻¹. - While mathematically correct for k, the question specifically asks for **clearance**, not the elimination rate constant. - Clearance is related to k by: Cl = k × Vd (volume of distribution).
Question 5: A pediatric patient presents with a 45-minute history of continuous convulsions. The senior resident (SR) recommends IV lorazepam, but the junior resident (JR) is unable to secure IV access. What is the next best step in management?
- A. Rectal diazepam (Correct Answer)
- B. Intramuscular phenobarbital
- C. Intramuscular midazolam
- D. IV phenytoin
Explanation: ***Rectal diazepam*** - Rectal diazepam is an **effective first-line alternative** when IV access cannot be obtained in status epilepticus - It has a **rapid onset of action** (within 2-5 minutes) and can be easily administered in emergency settings - **Widely available** and part of established pediatric seizure protocols globally - Both rectal diazepam and IM midazolam are acceptable alternatives per current guidelines *Intramuscular midazolam* - IM midazolam is **equally effective** and increasingly preferred in many modern protocols when IV access is unavailable - The RAMPART trial demonstrated **faster seizure cessation** with IM midazolam compared to rectal diazepam in prehospital settings - **Both IM midazolam and rectal diazepam** are considered first-line alternatives per WHO and major pediatric emergency guidelines - Either option is appropriate depending on local protocols and availability *Intramuscular phenobarbital* - Phenobarbital has a **slower onset of action** when given intramuscularly (15-30 minutes) - Typically reserved for **refractory status epilepticus** or as a second-line agent after benzodiazepines have failed - Not preferred as an immediate alternative to IV lorazepam *IV phenytoin* - IV phenytoin **requires IV access**, which is specifically unavailable in this scenario - It is a second-line antiepileptic for status epilepticus, used after benzodiazepines - Requires **cardiac monitoring** due to risk of hypotension and arrhythmias
Question 6: EDD ( Expected Date of Delivery) is calculated by:
- A. Cardiff Formula
- B. McDonald's rule
- C. Hadlock Formula
- D. Naegele's formula (Correct Answer)
Explanation: ***Naegele's formula*** - **Naegele's formula** is the most common and widely accepted method for calculating the estimated date of delivery (EDD). - It involves adding one year, subtracting three months, and adding seven days to the **first day of the last menstrual period (LMP)**. *Cardiff Formula* - The **Cardiff Formula** is a method used for assessing fetal movements, particularly for monitoring fetal well-being, not for calculating EDD. - It establishes a baseline of fetal movements over a specific period to detect any significant decrease. *McDonald's rule* - **McDonald's rule** is a clinical method used to estimate the gestational age based on fundal height measurements. - While it helps in estimating gestational age, it is not primarily used for calculating the precise EDD. *Hadlock Formula* - The **Hadlock Formula** refers to a set of widely used ultrasound-based formulas for estimating fetal weight and gestational age, typically involving biometry measurements like BPD, HC, AC, and FL. - While accurate for gestational age estimation, it's an imaging-based method, not a direct calculation of EDD from the LMP like Naegele's.
Question 7: 2 year old child with length 85cm and weight of 11kg was found to have serum urea of 49mg/dl, serum creatinine 2mg/dl What is the estimated GFR of this child, as per Schwartz formula?
- A. 48
- B. 9
- C. 19 (Correct Answer)
- D. 90
Explanation: ***19*** - The **Schwartz formula** for estimating GFR in children is: **GFR = k × (length in cm / serum creatinine in mg/dL)**. - For a 2-year-old child, the constant **k is typically 0.45**. Therefore, GFR = 0.45 × (85 cm / 2 mg/dL) = 0.45 × 42.5 = 19.125, which rounds to **19 mL/min/1.73m²**. - This GFR value indicates **moderate to severe chronic kidney disease** in a child. *48* - This value is likely obtained if an incorrect **k constant** was used (such as k = 0.55 for older children) or if there was a calculation error. - A GFR of 48 mL/min/1.73m² would indicate **moderate chronic kidney disease (Stage 3)**, but the calculation using the appropriate k value does not support this. *9* - This value would result from using an incorrect k value (possibly dividing 0.45 by 2) or making an **arithmetic error** in the calculation. - A GFR of 9 mL/min/1.73m² would suggest **severe kidney failure (Stage 5 CKD)**, which is inconsistent with the provided parameters when calculated correctly. *90* - A GFR of 90 mL/min/1.73m² or higher generally indicates **normal kidney function**. - This value is significantly higher than what would be calculated using the Schwartz formula with the given creatinine level of 2 mg/dL, which indicates significant kidney impairment in a child.
Question 8: For the treatment of kala-azar, the daily dose of miltefosine in a 3-year-old child who weighs 15 kg is
- A. 20 mg
- B. 40 mg (Correct Answer)
- C. 10 mg
- D. 30 mg
Explanation: ***40 mg*** - Miltefosine dosage for children weighing 12 to 29 kg (including a 15 kg child) is typically **2.5 mg/kg body weight per day orally**. - For a 15 kg child, this translates to 2.5 mg/kg * 15 kg = **37.5 mg**, which is rounded to **40 mg** for practical dosing since miltefosine capsules come in 10 mg or 50 mg sizes. *20 mg* - This dose is lower than the recommended **2.5 mg/kg/day** for a 15 kg child, which would be 37.5 mg. - An underdose of miltefosine could lead to **treatment failure** and the development of drug resistance. *10 mg* - This dose is significantly lower than the recommended therapeutic dose for a 15 kg child, which requires approximately **37.5 mg daily**. - Such a low dose would be **ineffective** in treating kala-azar, risking worsening disease. *30 mg* - While closer than 10 mg or 20 mg, 30 mg is still below the calculated **37.5 mg/day** for a 15 kg child. - An insufficient dose may compromise the efficacy of treatment and lead to **suboptimal parasitic clearance**.
Question 9: One year old male child with cat's reflex and raised IOP. What is the most likely diagnosis?
- A. Toxocara canis
- B. Retinopathy of prematurity
- C. Retinoblastoma (Correct Answer)
- D. Toxoplasma gondii infection
Explanation: ***Retinoblastoma*** - A **cat's reflex (leukocoria)**, which is a white pupillary reflex, is the most common presenting sign of retinoblastoma in children. - **Raised intraocular pressure (IOP)** can occur in advanced retinoblastoma due to secondary glaucoma caused by tumor growth or neovascularization. *Toxocara canis* - Ocular **toxocariasis** can cause leukocoria and inflammation, but it's typically associated with **granuloma formation** and not usually primary elevated IOP. - This condition is caused by a **parasitic infection** from roundworms, often seen in children with exposure to contaminated soil or pets. *Retinopathy of prematurity* - Primarily affects **premature infants** exposed to high oxygen, leading to abnormal retinal vessel development. - While it can cause leukocoria in severe stages, it would be unusual for a **one-year-old** to present with this primary diagnosis especially with raised IOP. *Toxoplasma gondii infection* - Ocular **toxoplasmosis** typically presents with **chorioretinitis** and can cause inflammation, but **leukocoria** and **raised IOP** are not its primary or most characteristic features. - This is a parasitic infection, congenital or acquired, often presenting with **retinal scars**.
Question 10: Treatment of choice for antrochoanal polyp in a 10-year-old child-
- A. Caldwell luc's
- B. Exploratory rhinotomy
- C. Conservative treatment till 16 years
- D. Intranasal polypectomy (Correct Answer)
Explanation: ***Intranasal polypectomy*** - **Intranasal polypectomy**, particularly via **endoscopic sinus surgery**, is the preferred treatment for antrochoanal polyps in children due to its minimally invasive nature and ability to ensure complete removal of the polyp's antral component. - This approach allows for direct visualization and removal of the polyp, including its origin from the **maxillary sinus ostium**, which is crucial to prevent recurrence. *Caldwell luc's* - The Caldwell-Luc procedure is a more invasive technique that involves creating an antrostomy through the anterior wall of the maxillary sinus. - It is associated with higher morbidity, including potential for **facial swelling**, **nerve damage**, and **dental complications**, making it less favored, especially in children, for antrochoanal polyps. *Exploratory rhinotomy* - **Exploratory rhinotomy** is a highly invasive surgical approach typically reserved for extensive or malignant sinonasal tumors. - It is an overly aggressive and unnecessary procedure for a benign condition like an antrochoanal polyp. *Conservative treatment till 16 years* - Antrochoanal polyps cause symptoms like **nasal obstruction** and potential ostial blockage, leading to sinus infections. - Delaying treatment is not advisable as it can lead to chronic symptoms, impaired quality of life, and potential complications from untreated sinus disease.
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