Pediatric and Geriatric Pharmacology

Pediatric and Geriatric Pharmacology Indian Medical PG Question 1: Pharmacodynamics deals with:-

• A. Latency of onset
• B. Mechanism of action of a drug (Correct Answer)
• C. Transport of drug across the biological membranes
• D. Mode of excretion of a drug

Pediatric and Geriatric Pharmacology Explanation: Detailed study of the **Mechanism of action of a drug** [1][2] - **Pharmacodynamics** describes what the **drug does to the body**, including its **molecular targets** and biochemical effects [3]. - This involves the study of the drug's mechanisms to produce its therapeutic or toxic effects [2]. *Latency of onset* - **Latency of onset** refers to the time it takes for a drug to start producing its effects, which is a pharmacokinetic rather than a pharmacodynamic parameter. - It deals with the drug's absorption and distribution rather than its interaction with the body once it reaches its site of action. *Transport of drug across the biological membranes* - The **transport of drugs across biological membranes** is a key aspect of **pharmacokinetics**, specifically absorption and distribution [1]. - This process determines how much drug reaches its target site, not how it interacts with the target. *Mode of excretion of a drug* - The **mode of excretion** of a drug (e.g., renal, hepatic) falls under **pharmacokinetics**, addressing how the body gets rid of the drug. - This process influences the drug's duration of action and elimination half-life, not its mechanism of action.

Pediatric and Geriatric Pharmacology Indian Medical PG Question 2: Which of the following medications is a first-line antitubercular drug used routinely in children of all age groups without significant monitoring limitations?

• A. Ethambutol
• B. Streptomycin
• C. Pyrazinamide (Correct Answer)
• D. Combination of all first-line ATT agents

Pediatric and Geriatric Pharmacology Explanation: ***Pyrazinamide*** - **Pyrazinamide** is one of the four core first-line antitubercular drugs (along with isoniazid, rifampicin, and ethambutol) [2, 4] and is used **routinely in children of all age groups** without significant monitoring limitations. - It is highly effective against **intracellular mycobacteria** in acidic environments, which are abundant in the early inflammatory stages of tuberculosis [1]. - Its inclusion is crucial for shortening the duration of treatment to 6 months and preventing the development of drug-resistant strains, especially in the initial intensive phase [3, 4]. *Ethambutol* - **Ethambutol** is indeed a first-line antitubercular drug, but its use in **children under 5 years** is often avoided or given with caution due to difficulty in monitoring for **optic neuritis** [1]. - Young children may not be able to reliably report visual changes (color vision defects, decreased visual acuity), making its safe administration challenging [1]. - WHO guidelines recommend avoiding ethambutol in children who cannot reliably report visual symptoms. *Streptomycin* - **Streptomycin** is an **aminoglycoside antibiotic** and is classified as a **second-line** (or alternative first-line) injectable antitubercular drug [3]. - It is primarily used for drug-resistant tuberculosis or in special circumstances where oral first-line regimens cannot be used. - It requires intramuscular injection and is associated with significant toxicities including **ototoxicity** (vestibular and auditory damage) and **nephrotoxicity**, making it unsuitable as a routine first-line option in children. *Combination of all first-line ATT agents* - While the standard treatment involves a **combination of four first-line drugs** (isoniazid, rifampicin, pyrazinamide, and ethambutol), this option describes a treatment regimen rather than answering which individual medication is a first-line drug [3]. - The question specifically asks for "which medication" (singular), making this option inappropriate as an answer.

Pediatric and Geriatric Pharmacology Indian Medical PG Question 3: Pseudotumor Cerebri in Infants is seen with?

• A. Aminoglycosides
• B. Tetracyclines (Correct Answer)
• C. Macrolides
• D. NSAIDs

Pediatric and Geriatric Pharmacology 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**.

Pediatric and Geriatric Pharmacology Indian Medical PG Question 4: The recommended dose of cotrimoxazole for treatment of pneumonia in a child weighing 16 kg is

• A. Four paediatric tablets twice a day
• B. Two paediatric tablets twice a day
• C. One paediatric tablet twice a day
• D. Three paediatric tablets twice a day (Correct Answer)

Pediatric and Geriatric Pharmacology Explanation: ***Three paediatric tablets twice a day*** - A paediatric cotrimoxazole tablet contains **20 mg trimethoprim + 100 mg sulfamethoxazole**. - The recommended dose for pneumonia is **4 mg/kg trimethoprim + 20 mg/kg sulfamethoxazole** twice daily. - For a 16 kg child: Required dose = **64 mg trimethoprim + 320 mg sulfamethoxazole** per dose. - Three tablets provide **60 mg trimethoprim + 300 mg sulfamethoxazole**, which is the closest appropriate dose to the calculated requirement. *One paediatric tablet twice a day* - This provides only **20 mg trimethoprim + 100 mg sulfamethoxazole** per dose. - This is **grossly inadequate** for a 16 kg child, providing less than one-third of the required dose. - Such underdosing risks treatment failure and antibiotic resistance. *Two paediatric tablets twice a day* - This provides **40 mg trimethoprim + 200 mg sulfamethoxazole** per dose. - While better than one tablet, this is still **subtherapeutic** for a 16 kg child with pneumonia. - This represents only about 60% of the recommended dose. *Four paediatric tablets twice a day* - This provides **80 mg trimethoprim + 400 mg sulfamethoxazole** per dose. - This is **slightly higher** than required but would risk unnecessary adverse effects. - Three tablets is the more appropriate choice for this weight range.

Pediatric and Geriatric Pharmacology Indian Medical PG Question 5: Which of the following drugs should be given in a sustained-release oral dosage form?

• A. An anti-arrhythmic drug with a plasma half life of 10 seconds used for acute treatment of PSVT
• B. Anti inflammatory drugs with the plasma half life of 24 hours
• C. Hypnotic drugs with a plasma half life of 2 hours
• D. An antihypertensive with a plasma half-life of 3 hours (Correct Answer)

Pediatric and Geriatric Pharmacology Explanation: *An anti-arrhythmic drug with a plasma half life of 10 seconds used for acute treatment of PSVT* - An extremely short **half-life** (10 seconds) indicates a drug suitable for **rapid-onset, acute interventions**, where the effect is needed immediately and for a very brief duration, making sustained release impractical. - Drugs like **adenosine**, used for acute PSVT, are given intravenously as a rapid bolus due to their ultra-short half-life, not in an oral sustained-release form. *Anti inflammatory drugs with the plasma half life of 24 hours* - A long **half-life** (24 hours) typically means the drug can be administered **once daily** to maintain therapeutic concentrations, rendering a sustained-release formulation unnecessary. - Such drugs already provide **prolonged action** and do not benefit significantly from further extension of release. *Hypnotic drugs with a plasma half life of 2 hours* - While a 2-hour half-life for a hypnotic might suggest potential for sustained release to prolong sleep, the goal of hypnotics is often a **rapid onset and relatively short duration** to avoid hangover effects. - Sustained release might cause **daytime sedation** and interfere with normal wakefulness, which is generally undesirable for this class of drugs. ***An antihypertensive with a plasma half-life of 3 hours*** - A short **half-life** (e.g., 3 hours) often necessitates frequent dosing to maintain therapeutic levels, making a **sustained-release formulation desirable** for patient compliance and consistent drug exposure. - Sustained-release dosage forms are particularly useful for drugs requiring **long-term, stable plasma concentrations**, such as antihypertensives, to manage chronic conditions effectively.

Pediatric and Geriatric Pharmacology Flashcard 1 of 5

Question: _____ is the most common adverse effect of phenytoin in children and young adolescents on chronic use.

Answer: Gum hyperplasia

Pediatric and Geriatric Pharmacology Flashcard 2 of 5

Question: An infant weighing 2-2.5kgs should recieve _____ daily dose of Nevirapine post-partum

Answer: 10mg

Pediatric and Geriatric Pharmacology Flashcard 3 of 5

Question: Which antithyroid drug in kids has been associated with fatal hepatotoxicity?_____

Answer: Propylthiouracil

Pediatric and Geriatric Pharmacology Flashcard 4 of 5

Question: Compared to other hypnotics, ramelteon has relatively _____ side effects and is safe to use in geriatric patients

Answer: few

Pediatric and Geriatric Pharmacology Flashcard 5 of 5

Question: An infant weighing less than 2kgs should recieve _____ daily dose of Nevirapine post-partum

Answer: 2mg/kg