These types of calculations are mostly done on the basis of common sense. Oramorph® is a controlled drug and therefore has a couple of extra requirements with its prescription, which are covered in more detail in the next section.

Prescribing Controlled Drugs

These drugs often cause the most confusion but, if you follow the simple rules below and are sensible, you should not go wrong!

When prescribing controlled drugs, the prescription must state:

The name and address of the patient

The form and strength of the drug (as appropriate)

Either the total quantity or the number of dosage units of drug written in both words and figures

The dose of the drug

The prescription must then be signed, dated, and also contain the prescriber’s hospital address. Without such information, the pharmacy will not prescribe the controlled drug.

For example, if a patient has been receiving morphine sulfate MR modified-release 5 mg oral BD in the hospital, you would prescribe it as shown in Table 10.3.

Table 10.3

Prescription for morphine sulfate modified release 5 mg BD

Station 10.2: Analgesia

Mr Smith is a 45-year-old surgical inpatient who has been diagnosed with appendicitis and is awaiting theatre. He has severe right iliac fossa pain and has not yet received any analgesia. Please prescribe appropriate medication, and indicate how you might proceed if the pain were to persist despite initial treatment.

Pain can be difficult to manage. Furthermore, the side effects of analgesics can be more damaging than the pain itself. A simple, structured approach to analgesia will help address these issues in the majority of cases.

Analgesia should be prescribed using the World Health Organization (WHO) analgesic ladder (Fig. 10.1) as a guide. Two general rules to note when using the WHO analgesic ladder are:

1. Start at the step most appropriate for the patient’s pain, e.g. if the patient has suffered a fractured femur and is complaining of severe pain, you should move straight to step 3, rather than trying step 1 and waiting to see if the pain settles

2. If the pain is not controlled, avoid changing one drug for another of equal potency in the same class, e.g. do not change codeine to dihydrocodeine. Instead move up the ladder until adequate analgesia is reached.

Figure 10.1

Non-Opioids

Paracetamol (1 g oral QDS) is an effective pain killer, and should be prescribed regularly to every patient who has pain.

Weak Opioids

If the pain is not controlled with regular paracetamol alone, a weak opioid should be added. Options include codeine phosphate (30–60 mg up to 4 hourly oral, max 240 mg/24 hours) and dihydrocodeine (30 mg up to 4 hourly oral/SC/IM).

Strong Opioids

If pain continues despite maximum doses of non- and weak opioids, the weak opioid should be stopped and a trial of strong opioids (e.g. morphine, oxycodone, fentanyl) commenced. Morphine has serious side effects and needs to be prescribed with care.

Adjuvants

These include non-steroidal anti-inflammatory drugs (for bony metastases, liver pain), corticosteroids (for nerve compression, liver pain, raised intracranial pressure), gabapentin and amitriptyline (for neuropathic pain). The nature of the pain will determine which adjuvant is appropriate and these should be considered with any step in the analgesic ladder. It is best to discuss the use of these drugs with a senior and/or the pain team.

Prescribing Morphine

Morphine can be either a standard (immediate-release) form acting for around 4 hours or a modified-release form acting for between 12 and 24 hours

It can be administered orally, IV, IM, SC or PR

In most acute scenarios, the oral route is the most appropriate. If this is not available other routes such as IM, IV, SC can be considered

One should be aware of the dosing differences when using these different routes (see below)

Most patients with continuous, acute, severe pain should initially be prescribed immediate release morphine (Oramorph®/Sevredol®)

This takes about 20 minutes to work and acts for approximately 4 hours

It is difficult to know how much morphine a patient will need. Therefore, it is best to prescribe it initially as an ‘as required’ medication (e.g. morphine, 5 mg oral PRN, maximum frequency 4 hourly)

The dose and frequency of the morphine can be adjusted according to the pain and degree of side effects (e.g. increasing to 5 mg oral PRN, maximum frequency 2 hourly, if the patient continues to be in pain)

Modified release morphine (MST Continus®/Zomorph®/Morphgesic SR®) takes longer to have an effect but lasts 12 hours

It is prescribed twice a day, after titration with immediate release morphine has achieved adequate analgesia

The dose of modified release morphine is calculated by taking the total amount of immediate release morphine used in 24 hours and dividing by 2

‘Break through’ immediate release morphine will also be required and is one-sixth of the total amount of immediate release morphine used in 24 hours

For example, if a patient had used 6×10 mg PRN doses of Oramorph® in 24 hours (i.e. 60 mg), 30 mg (60/2=30) of modified release morphine, such as MST, could be prescribed BD as well as Oramorph® 10 mg PRN 4 hourly (60/6=10)

It should be noted that MST should be used when Oramorph® is the PRN opioid, whereas Oxycontin® should be prescribed when Oxynorm® is the ‘break through’ opioid.

Table 10.4

Side effects of analgesics

Table 10.5

Equivalent doses of opioids

Oral morphine 5 mg	≈ oral codeine 60 mg
	≈ oral dihydrocodeine 60 mg
	≈ SC morphine 2.5 mg
	≈ oral oxycodone 2.5 mg

Side effects and cautions of commonly prescribed analgesics are shown in Table 10.4.

In those with renal impairment, instead of morphine or oxycodone®, consider alternatives such as alfentanil®, or fentanyl®.

For the majority of patients, the WHO analgesic ladder will provide sufficient analgesia. However, it will not be possible to control every patient’s pain with the above strategy. In these cases, discussion with your seniors and the pain team would be a useful next step.

Station 10.3: Dealing with a medication error

Mr Sanderson was admitted to the cardiology ward last night, and you are reviewing him on the ward round. You are asked to review him because he is noted to have a new rash. You find out that he is penicillin allergic, and yet was started on penicillin for a presumed chest infection. Please explain how you would go about managing the situation.

1. Ensure patient safety
Assess the patient using the ABCDE approach outlined in this book. Medication errors can potentially make patients critically unwell, so your first priority is ensuring no harm has been done

2. Verify the information
Check the prescription chart to see what medications have been prescribed and what has been given. Check for any documented allergies (a) on the drug chart, (b) in the medical notes and (c) with the patient, e.g. a wrist band, GP letter and verbally

3. Escalate to senior colleagues
Any medication errors like this need to be discussed with the consultant and the nurse in charge. It should not happen, and therefore needs to be looked into

4. Admit error to patient
The patient needs to be told early and directly that an error has been made due to a mistake made by the hospital and is the responsibility of the hospital. Emphasize that you have assessed them, and tell them if any direct harm has come of it. Emphasize as well that you take the error very seriously and that you and the hospital will thoroughly investigate why it happened. It should generally be the case that the consultant looking after the patient will want to meet with the patient and discuss what has happened as well

5. Identify why the error may have happened (root cause analysis)
There are two aspects to this. First, identify the circumstances of this specific case. Who was the doctor that prescribed the drug? In what circumstance was it prescribed? Were they working beyond their hours? Were they following direct instructions from a consultant/registrar on a ward round without double checking allergies? Had they had adequate prescribing training? Had the original drug chart been filled out correctly: was the drug allergy clearly documented? Which nursing staff gave the medication? What checks were taken to ensure the medication was safe to give?
Second, what could be done generally to reduce the likelihood of such an event happening again? This can be done by you and the team looking after the patient. In the above scenario, it became apparent that the ward did not use allergy bracelets for patients, and therefore this was changed. However, it must be escalated higher, and a critical incident form would need to be filled in to investigate this at the hospital level

6. Report the error
All hospitals have reporting systems to capture and analyze common errors so that lessons can be learned by staff, to provide a safer environment for all patients. These efforts are thwarted if the errors that occur go unreported. Most hospitals now operate a ‘no blame’ culture that encourages more frequent reporting

Station 10.4: Reporting an adverse drug reaction

Mr McMillan was started on a new antiplatelet agent, ‘sementy’, and within one week, was noted to have a reduced neutrophil count. He has been reviewed by the haematologists who felt the low neutrophil count was due to the new drug and, after discussion with cardiology, sementy was changed to clopidogrel, and the neutrophil count recovered. Your consultant has asked you to fill in a Yellow Card to report this error.

Suspected adverse drug reactions a common cause of hospital admission (7% of acute admissions) and affect up to 15% of inpatients. It is the duty of hospital prescribers to report them to a national agency that can pool the reports from around the country and begin to identify signals of previously unrecognized reactions. Reports are required not just for medicines but also for blood products, vaccines, herbal or complementary medicine products.

The more information provided the better, but this should not significantly delay the reporting of the reaction (or error).

The Yellow Card system is a voluntary reporting system in the UK, used to make reports to the Medicines and Healthcare Products Regulatory Agency (MHRA). Reports can be sent by healthcare professionals as well as patients and carers. Most reports are provided online at http://yellowcard.mhra.gov.uk. Similar pharmacovigilance schemes exist in other countries.

Medicines and Healthcare Products Regulatory Agency

The minimum information required for a Yellow Card is:

Patient information should ideally include age, sex, weight, initials, height, or local identification number

The name of the drug(s) suspected of causing the reaction, as well as any other drugs that the patient may be taking

A brief description of the adverse drug reaction

Contact details of the reporter (which should be your work contact information).

‘MM, a 60-kg, 52-year-old male, 5 foot 10 inches, has had a reported adverse reaction to sementy, 1 week after it being started. The neutrophil count significantly dropped, with other parameters remaining normal.’

Further information (though not essential) is of considerable value about:

The drug:

Start and stop date

Route of administration

Dose

Indication

Batch number

The adverse reaction:

Start and stop date

The outcome

Any treatment required

The patient:

Additional medications being taken (including over-the-counter medication, and any medication stopped in the preceding 3 months). Should include dose, route of administration and indication

Relevant medical history

Relevant recent blood test

Information on the outcome of any re-challenge with the suspect drug(s)

Indication of the seriousness of the reaction

‘He was started on sementry 30 mg orally once daily on 01/12/2014, for ischaemic heart disease, after having had a STEMI with single vessel disease, treated with percutaneous coronary intervention. The batch number of his first packet was 23839273. It was stopped on 07/12/2014, due to the low neutrophil count. No treatment was necessary. He has been on aspirin 75 mg orally once daily, bisoprolol 1.25 mg orally once daily, and ramipril 2.5 mg orally once daily since 01/12/14 for ischaemic heart disease. He has no other medical history.

On 07/12/14, he was noted to have a neutrophil count of 0.9×10⁹/L, having had bloods done because his GP was concerned that he looked anaemic. The haemoglobin, platelet, lymphocyte, clotting, renal and liver function were all normal. Two weeks later, (after stopping sementy) on 21/12/14 the neutrophil count was 7×10⁹/L.’

Table 10.6

Mr McMillan’s blood results 07/12/14

Parameter	Value	Normal range (Units)
Haemoglobin	140 g/L	Men: 135–177 (g/L) Women: 115–155 (g/L)
Neutrophil	0.9×10⁹/L	2.0–7.5 (×10⁹/L)
WCC	8.2×10⁹/L	3.2–11 (×10⁹/L)
Platelet	270×10⁹/L	150–400 (×10⁹/L)
PT	12 seconds	11.5–13.5 seconds
APTT	35 seconds	26–37 seconds
Urea	4.5 mmol/L	2.5–6.7 (mmol/L)
Creatinine	95 μmol/L	79–118 (μmol/L)
eGFR	>60 mL/min	>60 (mL/min)
Sodium	140 mmol/L	135–146 (mmol/L)
Potassium	4.2 mmol/L	3.5–5.0 (mmol/L)
CRP	2 mg/L	0–5 (mg/L)
Bilirubin	10 μmol/L	<17 (μmol/L)
ALT	27 IU/L	<40 (IU/L)
ALP	84 IU/L	39–117 (IU/L)

If no further information is available, it is best to say this, rather than omit anything, since that way the person reading the report will not need to follow it up.

Station 10.5: Blood product prescribing

As an orthopaedic junior doctor, you see Mr McDonald, a 67-year-old gentleman, with a past medical history of ischaemic heart disease, and peptic ulcer disease, who is day-1 postop for a left total hemiarthroplasty for a left neck of femur fracture. Intraoperative blood loss was estimated at 1500 mL. His preoperative Hb was 101 g/L and platelets 60×10⁹/L. He feels lethargic, dizzy and short of breath, and reports indigestion but no PR bleeding.

Patient Details

Initial Assessment

Airway, breathing, circulation, disability, exposure

Assess patency of the airway. Check respiratory rate, oximetry, auscultate chest. Assess BP and HR, capillary refill time. Assess conscious level, and blood glucose. Expose the patient, where appropriate to reveal clues (melaena, haematoma)

‘The airway is patent. RR 22/min, sats 97%, chest clear. HR 80 bpm, BP 123/72 mmHg lying and 120/65 mmHg standing. There is conjunctival pallor, heart sounds are normal. Patient alert, orientated. Blood sugar is 5.5 mol/L.

Temp 36.9°C. Exposure reveals a clean left hip wound, rosy urine in catheter, and soft non-tender abdomen. PR exam revealed mild haemorrhoids with no melaena, and gum bleeding. Fecal occult blood (FOB) is negative.’

The patient has clinical symptoms and signs of anaemia, with evidence of external bleeding from haematuria and gum bleeding. He is haemodynamically stable.

Tip: Where possible, anticipate when patients need blood transfusion samples, e.g. preoperatively in potential surgical cases (acute abdomen, hip fractures, etc.).

Initial Investigations

Bloods: Group and save, FBC. Check anaemia severity by measuring haemoglobin and, at the same time, a platelet count will help assess if thrombocytopaenia is contributory. In this case, the reduced haemoglobin is most likely due to operative and postoperative blood loss, so additional tests may not be necessary

Blood transfusion samples

Sample and request forms MUST comply with Mandatory Data Set requirements, including hospital ID number, surname, first name, DOB, signatures (prescriber, taking sample). Any missing/mismatching information means samples will NOT be accepted.

Tip 1: Always HANDWRITTEN (no sticky labels)

Tip 2: NEVER write on sample tube BEFORE drawing sample

Tip 3: Seek POSITIVE identification of patients at bedside. LABEL tubes immediately.

Indications for red cell transfusion

Symptomatic anaemia, which would generally be a Hb<100 g/L (dyspnoea, angina, syncope, ST depression on ECG)

Hb<80 g/L, or potentially lower if cardiovascular disease is present

However in general:

Check MCV, to determine whether it is a microcytic, macrocytic, or normocytic anaemia

Check B₁₂, folate, iron levels, and TFTs, as deficiency in all of the above may cause anaemia

Check LFTs including clotting, to ensure a coagulation disorder is not contributory

Check urea, as this is raised acutely in a GI bleed

If haemolysis suspected, LDH, and haptoglobin are useful markers of the degree of red blood cell break down. Reticulocyte count will allow a measure of how quickly red cells are being reproduced. Coombs’ test will help determine if there are antibodies to red cells in the blood stream causing haemolysis.

‘Hb 77 g/L, MCV 63 fl, platelets 15×10⁹/L, normal LFTs and coagulation screen, eGFR>60 mL/min. Your differential diagnosis is symptomatic postoperative microcytic anaemia secondary to ≈1500 mL intraoperative blood loss, with also peptic ulcer disease, haematuria and haemorrhoids as contributors. The cause of the low platelets is unclear, but it may be related to heparin.’

Table 10.7

Mr McDonald’s blood results

Parameter	Value	Normal range (Units)
Haemoglobin	77 g/L	Men: 135–177 (g/L) Women: 115–155 (g/L)
MCV	63 fL	80–96 (fL)
WCC	7.2×10⁹/L	3.2–11 (×10⁹/L)
Neutrophil	4×10⁹/L	2–7.5 (×10⁹/L)
Lymphocyte	2×10⁹/L	1.4–4 (×10⁹/L)
Platelet	15×10⁹/L	120–400 (×10⁹/L)
Urea	3.7 mmol/L	2.5–6.7 (mmol/L)
Creatinine	90 μmol/L	70–130 (μmol/L)
Sodium	142 mmol/L	135–145 (mmol/L)
Potassium	3.9 mmol/L	3.5–5.0 (mmol/L)
eGFR	>60 mL/min	>60 (mL/min)
ALT	23 IU/L	5–35 (IU/L)
ALP	45 IU/L	39–117 (IU/L)
Bilirubin	13 μmol/L	3–17 (μmol/L)
PT	12 seconds	11.5–13.5 seconds
APTT	30 seconds	26–37 seconds

You arrange a blood transfusion and, after discussion with haematology, a platelet transfusion. You give furosemide cover due to the history of ischaemic heart disease. You stop heparin and aspirin since they may be causing the low platelet count, and they are also increasing the risk of bleeding directly. The next dose of bisoprolol is due in the morning so you ask the morning team to review this. As well as anaemia, hypotension (exacerbated by bisoprolol) could be contributory to the initial symptoms of light headedness and shortness of breath, especially given active bleeding.

Types of red cell concentrates