THERAPEUTIC AND PHYSICAL INCOMPATABILITIES

Definition

            When two or more ingredients of  a prescription are mixed together the undesired change that may take place in the physical, chemical or therapeutic properties of the medicament is termed as incompatibility.

Classification

Incompatibilities are of three types:

1.      Therapeutic incompatibility

2.      Physical incompatibility

3.      Chemical incompatibility

THERAPEUTIC INCOMPATIBILITY

            Usually this incompatibility arises when one or more drugs produces response or intensity different from that intended in the patients.

Classification

A)    Over doses

B)    Under doses

C)    Improper consumption by the patient

D)    Contra-indicated drugs

A) Over doses: This can be subgrouped as follows:

Excessive single dose

            Sometimes a single dose may become overdose depending on the health of the patient e.g. a normal dose (taking body weight as 70 kg for an adult male) may be overdose for a lowly built person. However it should not be more than 2 to 3 normal dose.

Remedy: The pharmacist should consult the physician and clarify the dose.

e.g. 1   Rx

                        Atropine sulphate                    6 mg

                        Phenobarbital                          360 mg

            Make capsules.

            Label: One capsule to be taken three times a day before meals.

Comments: In this prescription the doses of both atropine sulphate and phenobarbital are 12 times the normal doses. The physician intended for 12 capsules to be dispensed but he has mistaken or may be it is an incomplete prescription. Hence, before dispensing the pharmacist should consult the physician again.

Correct prescription

            Rx

                        Atropine sulphate                    6 mg

                        Phenobarbital                          360 mg

            Make capsules. Supply 12 capsules.

            Label: One capsule to be taken three times a day before meals.

e.g. 2   Rx

                        Strychnine sulphate                 20 mg

                        Iron and ammonium citrate     500 mg

Prepare capsules. Supply 12 capsules.

Label: One capsule to be taken three times a day after meals.

Comment: 10 times overdose of strychnine hydrochloride than that of normal. The pharmacist should consult the physician and obtain the permission to change the dose.

Corrected prescription

                        Strychnine sulphate                 2 mg

                        Iron and ammonium citrate     500 mg

            Prepare capsules. Supply 12 capsules.

            Label: One capsule to be taken three times a day after meals.

Excessive daily dose

            In this case the daily dose of drug is excee