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THE EASY GUIDE
INTRODUCTION
A prescription should be considered a carefully monitored experiment designed to maximise benefit & reduce
risk in an individual patient. As a consequence, safe and rational prescribing requires an understanding of the
processes contributing to drug use as well as acquiring the essential skills & attitudes required for good
prescribing. These include
♦ assessing the presenting problem & making a diagnosis
♦ assessing the need for drug therapy, including consideration of non-drug treatment
♦ establishing therapeutic endpoints in association with the patient
♦ choosing a preferred drug & a corresponding dosage schedule
♦ assessing the suitability of the chosen drug for the individual patient
♦ writing the prescription
♦ establishing the need & method for drug therapy monitoring & patient follow-up, including when to STOP
♦ verbally communicating this information & additional warnings to the patient or carer♦ providing written information to support the verbal communication Authors: Dr S Shakib, Dr N Buckley, Dr G Misan INTRODUCTION CONTINUED….
In addition doctors should make a commitment to lifelong self-education in therapeutics including: ♦ the use of unbiased sources of drug & therapeutic information,♦ the evidence base which supports the decision to prescribe a particular drug in a particular patient♦ an awareness of the cost and effectiveness of drug treatments The following pages provide a guide to some of these processes & principles.
, which students areencouraged to read and refer to regularly as part of this curriculum.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan PRESENTING PROBLEM
This is the patient’s diagnosis.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan THERAPEUTIC GOAL
This is what you want your therapy to achieve put in terms of what it means to the patient. A useful way ofthinking of it is that the therapeutic goal is the answer to the patient’s question of “why am I taking thismedication?” .
Hence, in the management of hypertension, the therapeutic goal is to prevent cardiovascular events rather thanreduce the blood pressure. In the management of heart failure, the therapeutic goals may be the management ofsymptoms, prevention of mortality, and prevention of hospitalization, rather than control of neurohormonalactivation.
The important issue is that the therapeutic goal will be different for different patients, and different drugs mayachieve some therapeutic goals but not others e.g. all treatments for acute migraine help with the headache , butif a patients has the therapeutic goal of being able to carry on with their normal activities, opiate analgesics areunlikely to allow them to achieve this whereas a 5HT1 agonist such as sumatriptan will.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan IDENTIFYING DRUG AND NON-DRUG OPTIONS
For many conditions non-drug options are as efficacious (e.g. salt restriction and weight loss with hypertension),
or are a useful adjunct to pharmacological therapy (e.g. salt restriction with cardiac failure, relaxation therapy for
pain disorders, hip protectors to prevent hip fractures in patients with osteoporosis). For other conditions, non-
drug therapy represents another modality for achieving the therapeutic goal e.g. cognitive behavioral therapy to
prevent recurrence of depression, smoking cessation to reduce risk of cardiovascular events with hypertension,
implantable defibrillators for ventricular arrhythmias. For other conditions, non-drug therapy may represent a
effective way of preventing acute exacerbations of an illness e.g. avoidance of precipitating factors for asthma
and migraine.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan USE OF SOURCES OF OBJECTIVE INFORMATION
Objective sources of drug information include the Australian Medicine’s Handbook, Therapeutic Guidelines and
the Australian Prescriber. These references contain information derived independently of the pharmaceutical
industry and include comparisons between drugs and drug groups.
Other sources of information include the medical literature and the Cochrane database. All health professionalsshould develop skills in literature appraisal.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan CHOOSE P-DRUGS FOR THE CONDITION UNDER CONSIDERATION USING THE
CRITERIA OF COMPARATIVE EFFICACY, SAFETY, COST AND CONVENIENCE
The P drugs are the drugs which you have chosen to prescribe regularly, and with which you will become
familiar. The P in P-drug can mean Preferred drug or Personal or Priority choice. They are your priority choice
for a given indication.
The P-drug concept is more than just the name of a pharmacological substance, it also includes the dosageform, dosage schedule and duration of treatment. P-drugs will differ from country to country, and betweendoctors, because of varying availability and cost of drugs, different national formularies and essential drugs lists,medical culture, and individual interpretation of information. However, the principle is universally valid. P-drugsenable you to avoid repeated searches for a good drug in daily practice. And, as you use your P-drugs regularly,you will get to know their effects and side effects thoroughly, with obvious benefits to the patient.
The choice of which you chose as the P-drugs will be based on their comparative efficacy, safety, cost and
convenience.
All drugs have to prove their efficacy in order to be registered in Australia, hence it is their efficacy compared to
other drugs that is the relevant issue. Also, some drugs may have proven efficacy in affecting a surrogate
endpoint e.g. blood pressure, bone mineral density, or HIV viral load, compared to other drugs for which patient
outcomes may be available e.g. cardiovascular events, hip fractures, survival, respectively. As already stated, a
drugs may have efficacy for some but not all of the therapeutic goals for a patient e.g. benzodiazepines may
provide symptomatic relief in patients with panic disorder, but some serotonin reuptake inhibitors have been
shown to treat the underlying depression as well.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan P-DRUGS CONTINUED….
When considering the safety of a drug it is important to consider the incidence as well as the severity of adverse
reactions. It is also important to appreciate special groups who may be particularly at risk of adverse reactions
e.g. the incidence of adverse reactions with serotonin reuptake inhibitors is only slightly less than that of tricyclic
antidepressants. However, whereas the former tends to cause predominantly mild gastrointestinal and CNS
side-effects the adverse reactions with the latter are more serious including postural hypotension, sedation,
seizures, and cardiac effects. These reactions can also be particularly troublesome in elderly patients. Similarly,
tricyclic antidepressants are more dangerous in overdose, hence they are less safe than the SSRI’s in patients
at risk of this.
The cost of a drug includes consideration of the cost to the patient as well as to the community in the case of
subsidised drugs. Cost also needs to include consideration of cost associated with monitoring, treatment failure,
and side effects.
The convenience of a drug is a broad issue that has to do with the drug’s formulation, frequency of dosing, as
well as other issues. The formulation of a drug is an important consideration for many patients. Although, most
drugs are administered orally, this may not be possible for many patients e.g. those who cannot swallow or are
vomiting, and parenteral administration may be required. Alternatively, PR dosing may not be acceptable for
some patients and the oral route may be preferred. The leukotriene antagonists are another example of where
drug convenience is an issue, because as they are administered orally, they may be more convenient for
patients with mild asthma than inhaled corticosteroids.
The other common area of convenience has to do with the frequency with which the medication needs to beadministered, once daily medications being more convenient than drugs dosed more frequently.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan P-DRUGS CONTINUED….
Convenience is also pertinent to combination tablets. Although they are more convenient from the point of viewof compliance, they do not allow dosage modification, and are not convenient for patients who require frequentdosage adjustment e.g. asthma patients needing frequent alteration in inhaled steroid dosage.
There are also other broader issues to do with drug convenience. The drug perhexiline, although, an effectiveanti-anginal requires regular monitoring of its drug levels in order to prevent toxicity. Similarly, warfarin is aneffective anticoagulant for atrial fibrillation, but requires regular measurements of INR, and some understandingon the part of the patient about interacting drugs.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan YOUR PERSONAL FORMULARY OF P-DRUGS
On the basis of the above criteria, chose drugs that you would prescribe for different indications, and these
together make up your Personal Formulary. These represent drugs that you will prescribe commonly and
become most familiar with.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan VERIFY SUITABILITY
Not all drugs may be suitable for all patients, so although you may have chosen to put a drug into your P-formulary on the basis of the above criteria, there may be reasons why you may not chose to prescribe it for anindividual patient. Most suitability issues have to do with safety and the fact that most drugs have acontraindication to their use. Drug allergies, or previous adverse drug reaction is a common example, and otherexamples include β-blockers in asthmatics, metformin in patients with renal failure, warfarin in patient with ahistory of falls and many others.
As well as contraindications, a patient may have a co-indication which may make a particular drug more suitablefor their treatment. A good example of this is seen in the management of hypertension where any of four (4)major drug classes may be chosen, but β-blockers and calcium channel blockers have a co-indication of anginaas they treat both, and ACE-inhibitors have the co-indication of heart failure.
Cost may present suitability issue for some patients e.g. the use of 5HT1 agonists for the treatment of migraine,or the use of neuraminidase inhibitors for influenza compared to symptomatic management alone.
There are other reasons why a drug may not be suitable as well. For some cancer patients with chronic pain theinitiation of morphine represents the end, and so morphine may not be suitable for them psychologically, butthey may be quite happy with other opiates or other types of analgesia.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan WRITE THE PRESCRIPTION
This should include the generic name of the drug, the dose, frequency, mode of administration, and ideally the
duration of the course if this is known. The prescription should also take into account of various legal and
regulatory requirements that may apply in different prescribing environments, eg narcotics or PBS items.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan INFORMATION TO THE PATIENT
This should include the therapeutic goal and how it will be achieved, as well as instructions regarding theadministration of the medication. This should also include the likely expected effects, and side-effects of themedication, as well as any other relevant instructions, e.g. common food/drug interactions. The informationshould be written down, as well as explained verbally. Consumer medicines information leaflets are an excellentway of communicating much of the information that a patient requires about a particular drug.
In certain circumstances it will be necessary to provide information to parents or carers and to arrange forinterpreters when individuals do not speak English well.
Remember too that some people have difficulty reading or hearing or understanding so tailor the informationaccordingly.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan INFORMATION TO OTHER PROFESSIONALS
Patients can receive care from different health professionals so it is important to ensure that adequate
information about changes to treatment or about treatment objectives is provided to others who may see the
patient after you. The General practitioner, pharmacist and specialists should be advised of treatment plans and
objectives.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan MONITORING THE EFFECTS OF TREATMENT
This is to monitor the effects and side effects of treatment in order to determine if the dosage of the medicationshould be adjusted or the treatment stopped. This will include checks of laboratory results (eg drugconcentrations, renal and liver function) as well as monitoring the impact of therapy on signs and symptoms.
Authors: Dr S Shakib, Dr N Buckley, Dr G Misan

Source: http://www.nswhealth.moodle.com.au/DOH/Child_Prescribing/EasyGuide.pdf