Metoprolol tartrate is very soluble
in water and appears to be very stable in aqueous solution.1,2
Peterson et al1 investigated the
stability of metoprolol oral liquid but this was formulated with tragacanth
and chloroform water. Metoprolol 10mg per mL prepared from tablets
in a 1:1 mixture of Ora-Sweet and Ora-Plus, or a 1:1 mixture of Ora-Sweet
SF and Ora-Plus, or Cherry Syrup was stable for up to 60 days at 5°C
or 25°C, protected from light.2
The final pH of these formulations ranged from 3.4 - 5.4.1,2 The
following formula is based on a review of the literature and is suggested
if the commercial bases are not available.
Formula
Metoprolol Tartrate Oral Liquid |
| |
| Metoprolol
tablets (not modified release) |
qs |
|
| Glycerol |
40 |
mL |
| Parabens |
0.1 |
% |
| Water |
to 100 |
mL |
| |
| Expiry: 30
days (suggested). |
| |
| Storage: Refrigerate. Protect
from light. |
| |
Shake
before administration |
|
|
|
NOTE
- Methylcellulose could be added as a suspending agent but is not necessary as the drug should be in solution. The glycerol content can be increased, or syrup added, to increase viscosity.
REFERENCES
- Peterson G.M., Meaney M.F., Reid C.A., Taylor G.R. Stability of
extemporaneously prepared mixtures of metoprolol and spironolactone. Aust J Hosp Pharm
1989; 19 (6): 344-46.
- Allen L.V., Erickson M.A. Stability of labetalol hydrochloride,
metoprolol tartrate, verapamil hydrochloride and spironolactone with
hydrochlorothiazide in extemporaneously compounded oral liquids. Am
J Health-Syst Pharm 1996; 53: 2304-9.
|