A 70-year-old man is scheduled for circumcision due to phimosis and requires a penile block with local anaesthetic. He weighs 65 kg. The maximum safe dose of lidocaine is 3 mg/kg, and 7 mg/kg when combined with adrenaline. What is the safest option for local anaesthetic in this patient?
You are evaluating a new drug X, which follows a linear pharmacokinetic pattern. Peak plasma concentration is measured at 0.4 mg/ml. Twelve hours later, the plasma concentration is 0.1 mg/ml.
Which of the following best reflects the half-life of drug X?
A patient who is having an excision of a large squamous cell carcinoma (SCC) on his back has had 20 ml of lidocaine 0.5%, but is still able to feel pain. You know that the maximum safe dose of lidocaine is 3 mg/kg and he weighs 70 kg.
How much more lidocaine can you give?
You are the surgical foundation year 1 doctor and have been bleeped by the nurse on the surgical ward regarding a 66-year-old patient who had a laparotomy for large bowel obstruction 2 days ago. On attending the ward the nurse reports that she thinks the patient is becoming unconscious with a drop in respiratory rate to eight breaths per minute. You have tried to secure the patient’s airway and noted on the drug chart that patient has been using the patient controlled analgesia with morphine regularly.
Which of the following is the next appropriate treatment?
A new vaccine is being tested in healthy volunteers with normal immune function. It is distributed in the lymphatic system only and has limited renal excretion.
A subcutaneous injection of the vaccine is given at 9:00 am and a peak antibody response is reached at 10:00 am. The levels of antibodies in the blood serum at various time points are given below:
Time Antibody concentration
10:00 200 IU/mL
12:00 100 IU/mL
14:00 50 IU/mL
What is the half life of this vaccine?
What is the most suitable time to collect blood samples for therapeutic monitoring of lithium levels?
A GP registrar has diagnosed a urinary tract infection in a 3-year-old child.
Urine cultures and sensitivity show the organism is sensitive to amoxicillin.
The child weighs 12 kg. The dose of amoxicillin is 20 mg/kg three times daily in a pharmacological preparation which contains 125 mg/5 ml.
What is the appropriate dose to be prescribed?
Choose the correct dosing schedule:
An 83-year-old man comes to the Emergency Department complaining of increased pain from his metastatic prostate cancer. He has been taking morphine sulphate modified release tablets orally at a dose of 60 mg twice a day, but the registrar has recommended switching to subcutaneous administration due to his inability to tolerate oral tablets and vomiting.
What is the appropriate dosage of morphine for a continuous subcutaneous infusion over a 24-hour period?
A 48-year-old man is recovering on the ward after a cholecystectomy. Upon examination, there are no concerns, and it is decided to prescribe pain relief. However, he has been experiencing nausea and has been unable to keep down food or fluids for the past hour. His drug chart shows that he has taken eight 500 mg tablets of paracetamol today, and he weighs 75 kg. There are no recorded allergies. What is the most suitable form of analgesia to offer?
A 20-year-old woman is brought to the hospital due to an acute overdose of her lithium medication, which she takes for bipolar affective disorder and self-harming tendencies. Upon admission, she displayed symptoms of vomiting, tremors, and first-degree heart block. Her lithium levels were measured at 3.6 mmol/l and after eight hours, it decreased to 3.0 mmol/l.
What is the estimated time for the lithium levels to drop to an undetectable level in the serum from the initial value of <0.25 mmol/l?