Liquid oral solutions drug concentration

Concentrated oral solution - Mix with liquid or semi-solid food such as water, juices, soda or soda-like beverages, applesauce, and puddings. Draw into the dropper the amount prescribed for a single dose. Then squeeze the dropper contents into a liquid or semi-solid food. Stir the liquid or food gently for a few seconds. The entire amount of the mixture, of drug and liquid or drug and food, should be consumed immediately. Do not store for future use. 

S5 ps are the liquid oral preparation made in concentrated sugar solution, mainly for paediatric use and for drugs which are unpleasant in taste. 

The maximum volume of liquid that can be administered orally at one time depends on the size of the test animal. For instance, in rodents, the volume should not exceed 1 mL/100 g body weight. In cases of aqueous solutions, the concentration must be adjusted to ensure a constant volume at all dose levels. If a dose of at least 5,000 mg/kg body weight using the above procedure produces no chemical or drug-related mortality, a full study using three dose levels may not be necessary. 

The delivery of freeze-dried preparations can be performed by different routes oral, nasal, anal, pulmonary, transdermal and parenteral. Of these routes, some do not require any treatment of the drug before it is administered, e.g. in the form of powders or tablets or in inhaling devices. For parenteral administration, however, whether by injection or infusion, the freeze-dried cake must be returned to a liquid state, a process referred to as reconstitution . The main vehicle will normally consist of water for injection or a solution, the concentration of which will establish isotonicity. The time required for the complete dissolution of the cake may in some cases be critical and should therefore be known. 

The pharmacist should have anticipated the bio-pharmaceutical consequences of the physico-chemical properties of oxcarbazepine. The drug is classified as a Class II substance for oral application. Logically, lack of adequate solubility is even more evident for the rectal administration as the volume of rectal fluid is limited (see Table 17.1). With an aqueous solubility of approximately 300 mg/L, the solubUity of the substance in the lipophilic base of the suppositories would certainly not be higher than 9.5 mg/mL (being a direct consequence of the value of the log P = 1.5 of oxcarbamazepine). This means that oxcarbazepine is not dissolved in the lipid but dispersed as crystals, which settle from the molten suppository once introduced in the rectal cavity. The amount of rectal liquid is limited and therefore a saturated solution will exist which involves only less than 1 mg dissolved oxcarbamazepine. Low solubility yields a low concentration and hence a low driving force for diffusion to occur. As a consequence, the rate of absorption is relatively low. This slow release may lead to hardly any uptake, due to defecation within several hours after insertion. 

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