Liquid dosage formulation

Although fish oils are used for human consumption, vegetable oils are more typically used in oral liquid dosage formulations. 

Importantly, barbiturates posed certain serious hydrolytic problems with regard to their incorporation in the liquid dosage formulations, such as parenterals and elixirs. It has been duly observed... 

Liquid Dosage Forms. Simple aqueous solutions, symps, elixirs, and tinctures are prepared by dissolution of solutes in the appropriate solvent systems. Adjunct formulation ingredients include certified dyes, flavors, sweeteners, and antimicrobial preservatives. These solutions are filtered under pressure, often using selected filtering aid materials. The products are stored in large tanks, ready for filling into containers. QuaUty control analysis is then performed. 

As mentioned earlier in this chapter, penicillins are very unstable in aqueous solution by virtue of hydrolysis of the p-lactam ring. A successful method of stabilizing penicillins in liquid dosage forms is to prepare their insoluble salts and formulate them in suspensions. The reduced solubility of the drug in a suspension decreases the amount of drug available for hydrolysis. An example of improved stability of a... 

It should again be emphasized that at the onset of a new drug program, there are only small amounts of drug substance at hand. One of the first tasks for the preformulation scientist is to establish the framework within which the first clinical batches can be formulated. To this end it is important to know with which common excipients the drug is compatible. Below, the distinction will be made between solid and liquid dosage forms. 

Extemporaneous production of pediatric dosage forms is commonly undertaken in hospitals. Without the sophisticated formulation capabilities of pharmaceutical manufacturers, alcohol-based vehicles have been recommended for extemporaneous preparation of liquid dosage forms [73]. There is a critical need to conduct research studies to assist the pharmacist in replacing current formulations with stable, alcohol-free preparations [74]. 

Oral Administration. Oral administration is the preferred route of administration. There is a general consensus among pediatricians and parents that children younger that 5 years of age have great difficulty with, or are unable to swallow, a solid oral dosage form. Manufacturers, therefore, have developed liquid formulations for many of the commonly used pediatric products. The liquid dosage form, however, is not free of problems. Liquid products are often unstable and have short expiration dates accurate measurement and administration of the prescribed dose is also a problem, especially in infants. 

Numerous reports concerning the stability of neomycin in various dosage forms have been published. Simone and Popino298 studied the stability of neomycin in liquid dosage forms such as nasal drops, mouth washes and tinctures. The antibiotic was stable in all the formulations tested, except Dobells solution (a mouth wash), for at least 6 months at 20°C. Some formulations were stable for considerably longer. 

Posaconazole is the newest triazole to be licensed in the USA. It is available only in a liquid oral formulation and is used at a dosage of 800 mg/d, divided into two or three doses. Absorption is improved when taken with meals high in fat. Posaconazole is rapidly distributed to the tissues, resulting in high tissue levels but relatively low blood levels. Visual changes have not been reported, but drug interactions with increased levels of CYP3A4 substrates such as tacrolimus and cyclosporine have been documented. 

A variety of different artificial sweeteners have been approved for use in oral liquid dosage forms by the FDA. One general characteristic for artificial sweeteners is their very high sweetness compare to sucrose. This also results in a much lower concentration needed in the formulation, which can lower the cost and/or risk of incompatibility with the drug or other excipients. Additionally, a sugar-free formulation... 

It is essential to understand how and when the polymorphs of drug substance in oral liquid dosage forms and suspensions can be controlled. One approach to study this phenomenon is to seed the formulation with a small amount of a known polymorphic crystal (other than what is used for the product), which is a common practice to rapidly determine what effect this may have on long-term storage. From these types of studies, the appropriate excipients can be used to preserve the specific polymorphic form desired. However, even when the drug in its crystalline form is studied extensively, there are cases when a previously unknown polymorph may be formed in solution and lead to precipitation (14). 

Use of these semisolid and solid approaches can potentially alleviate the chemical stability problems sometimes observed for liquid-Llled formulations, and may eventually offer the possibility of development of a tablet dosage form using conventional equipment. Liquid lipid-based formulations, however, generally afford the greatest enhancement of bioavailability for water-insoluble drugs, as well as affording more rapid development for First-in-Human studies. Any decisions on the best formulation route would have to be evaluated on a case-by-case basis. 

Stewart and Tucker assert that hydrolysis is affected by pH, buffer salts, ionic strength, solvent, and other additives such as complexing agents, surfactants, and excipients, and each of these factors is discussed in some detail. Waterman et al. (31) provide a comprehensive treatment of hydrolysis as it relates to pharmaceuticals, with thorough discussions of mechanisms, formulation considerations, pH, ionic strength, buffers, solid-state considerations, hydrolysis of lyophiles, liquid dosage forms, packaging, etc. 

Multiple dosage formulations (oral tablet, oral liquid, rectal gel, injectable) allow more flexibility of administration compared to most other benzodiazepines... 

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