The Medicines Control Council (MCC) recommends that substitution should not occur when prescribing and dispensing medicines which:
a) Have a narrow therapeutic range;
b) Have been known to show erratic intra- and inter-patient responses;
c) Are contained in dosage forms that are likely to give rise to a clinically significant bioavailability problem, e.g. extended or delayed release preparations, as well as those known to be super bioavailable*;
d) Are intended for the critically ill and/or geriatric and paediatric patients.
In terms of the above-mentioned factors, the following medicines have, on occasion, been known to present bioequivalence problems and should ideally not be interchanged with a generic:
- Alendronate tablets or capsules
- Atenolol tablets or capules
- Carbamazepine tablets
- Chlorpromazine tablets
- Dexamethasone tablets
- Diethystilboestrol tablets
- Digoxin tablets
- Disulfiram tablets
- Ethinyl Oestradiol tablets
- Fluoxymesterone tablets
- Furosemide tablets
- Glibenclamide tablets
- Hydralazine, hydrochlorothiazide and Reserpine combination tablets
- Hydralazine & Hydrochlorothiazide combination tablets
- Hydrocortisone tablets
- Hydrocortisone Acetate injection
- Isoproterenol Metered dose inhaler
- Isoethrane Metered dose inhaler
- Isorbide Dinitrate sustained release tablets and capsules
- Itraconazole tablets or capsules
- Levodopa Capsules and tablets
- Nfedipine: all extended/delayed release formulations
- Oestrogens, Conjugated tablets
- Oestrogens Esterifies tablets
- Penicillin G Benzathine injections
- Phenytoin tablets and capsules
- Phytomenadion injection
- Prazosin Hydrochloride tablets 5mg*
- Prednisolone tablets
- Prednisolone Acetate injections
- Prednisolone Tebutate injection
- Prednisone tablets
- Promethazine tablets
- Propylthiouracil tablets
- Reserpine tablets
- Reserpine and Chlorothiazide combination tablets
- Reserpine & Trichloromethiazide combination tablets
- Tamoxifen tablets or capsules
- Theophylline controlled release tablets/capsules
- Triamcinolone tablets
- Trichloromethiazide tablets
- Warfarin Sodium tablets
Non-inclusion of any particular medicine does not necessarily mean it is substitutable. The list is periodically reviewed, and alterations are made at the discretion and recommendation of the MCC.
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