INCOMPATIBILITIES IN PRESCRIPTION (PART 2)

 

INCOMPATIBILITIES IN PRESCRIPTION

PART 2

INCOMPATIBILITIES IN PRESCRIPTION (PART 1)

Hey guys, this is Sarang More here with another blog. Please have a look on this blog as it will help you to clear your concept. Share it to your friends and family and other pharma family.

·     THERAPUETIC INCOMPATIBILITY: -

Therapeutic incompatibility may be as a result of prescribing certain drugs to a patient with intention of producing the certain degree of pharmacological action, but the nature and intensity of action produced is different from that intended by the prescriber.

These occur due to following reasons-

a) Error in dosage.

b) Wrong dose or dosage form

c)  Contraindicated drugs

d) Synergistic drugs and antagonistic drugs

e) Drugs interaction

f)   Prescribing drugs with wrong dosage form

 

a)  Error in dosage: -

Many therapeutic incompatibilities result from error in writing or interpreting the prescription order. The most serious dosage error in the dispensing is the overdosing of the medication.

It becomes the duty of the pharmacist to check the prescription before dispensing it. Pharmacist is often in position to detect such errors and help to avoid such problems.

Example 1:

Rx

Atropine sulphate         0.006g

Phenobarbitone             0.015g

Aspirin                              0.300g

Prepare 10 capsules

In this prescription the quantity of atropine sulphate in each capsule is more than its maximum recommended dose. So the prescription is referred back to the prescriber to correct the dose of atropine sulphate.

Example 2:

Rx

Codeine phosphate          0.5g

Prepare 10 powder

Direction: one powder to be taken at the bed time.

This is an example of an overdose. The intention of the prescriber may be to prescribe 5 mg and yet to be prescribed 500mg in the prescription

So, the prescription is referred back to the prescriber.

 

b). wrong drug or dosage form: -

There are certain drugs which have quite similar names and there is always a danger of dispensing the wrong drug.

For example: prednisone and prednisolone, digoxin and digitoxin.

Sometimes many drugs are available in different dosage form and hence if dosage form are not clearly mentioned on the prescription, it becomes necessary to seek the clarification from the prescriber.

 

c). Contraindicated drugs: -

There are certain drugs which may be contraindicated in a particular disease or for a particular patient who is allergic to it.

For example: corticosteroids are contraindicated in the patients having active peptic ulcer. The penicillin and sulfa drugs are contraindicated to the patient who are allergic to it. Barbiturates and morphine must be contraindicated to the patient having asthma.

 

d). Synergistic drugs and antagonistic drugs: -

Many drugs exhibit synergism and antagonism when administered in combination. When two drugs are prescribed together, they tend to increase the activity of each other. This is known as synergism.

Synergism is intentional used to increase to the activity of drugs.

For example: a combination of aspirin and paracetamol increase the analgesic activity.

Similarly, the activity of aspirin and streptomycin increase the antibacterial properties of antibiotics.

There are certain drugs which when prescribed may lead to disastrous consequences. This prescription should refer back to the prescriber.

Example 1: -

Rx

Amphetamine sulphate         20mg

Ephedrine sulphate                100mg

Syrup up to                                 100ml

Make a mixture

In this prescription, there is combination of two sympathomimetic drugs with additive effect. So, there is need to reduce the dose of each drug.

The prescription should refer back to the prescriber.

When two drugs having the opposing pharmacological effects are prescribed together antagonism occurs.

Example 2: -

Rx

Acetyl salicylic acid        0.6g

Probenecid                       0.5g

Acetyl salicylic acid and probenecid are used in treatment of gout.

However, these combination leads to neutralization. Refer back the prescription to the prescriber.

 

e). Drug interaction: -

The effect of one drug is altered by the prior or simultaneous administration of another drug.

The drug interaction can usually correct by proper adjustment of dosage if the suspected interaction is occurred.

Example: -

Rx

Acetophenetidin                    150mg

Acetyl salicylic acid                 200mg

Caffeine                                     30mg

Send 10 capsules

Acetophenetidin and acetyl salicylic acid are analgesics. Acetophenetidin are CNS depressant has undesirable side effects.

Caffeine is CNS stimulant to neutralize the action of acetophenetidin. The incompatibility is intentional so dispense as it is.

 

f). Prescribing drugs with wrong dosage form : -

In certain prescriptions, the directions written by the prescriber makes it extremely difficult for the pharmacist as well as patient to understand and execute the prescription. Such prescriptions are deemed as wrong prescriptions.

Examples:

§  In case of tetracycline capsules

 Direction: One capsule needs to be taken for every six hours along with milk.

 Calcium present in the milk inactivates the tetracycline present in the capsule leading to therapeutic incompatibility.

§  In case of ointment

 Direction: To be applied two to three times in a day to eyes.

 Skin ointments are not sterilized, which is taken as prime consideration for eye ointments leading to therapeutic incompatibility.

§  In case of non-sterile solutions

 Direction: Inject 5 ml intra muscularly (i.m). Maintenance of sterility and isotonicity is taken as the foremost requirement for injectable formulations.

So, the given examples show therapeutic incompatibility, which can be traced out easily by the pharmacists if they had gone through the prescription thoroughly and can avoid occurrence of therapeutic hazards.