Drugs dissolved

Litholytic agents in current use are classified as direct or indirect. Indirect type drugs decrease the C.P. of urine, thus inhibiting calculus formation. An example is citrate which helps prevent insoluble salts from crystallizing in the urinary tract. Potassium citrate is administered in pill form as a preventive drug. Direct type drugs dissolve renal calculi which have already formed. 

Although not directly related to aqueous solubility, the state of the drug dissolved in another solvent, most notably in 1-octanol, has been used often in the computa-hon of aqueous solubility. Hansch [9] introduced the simple linear relahonship of... 

The last state in Fig. 11.1 that has not yet been discussed is the state of the neat liquid compound X. For liquid compounds this is the relevant initial state for solubility, but almost aU drug-Uke compounds are solid at room temperature. In this case the neat liquid is a virtual state of a supercooled liquid which can hardly be accessed experimentally. However, it is an interesting intermediate state because it allows us to split the calculation of solubility into two separate steps, which are conceptually and for some methods computationally easier to handle than the complete step from the crystaUine state of the drug to the liquid state of the drug dissolved in water. In the first step we only have to transfer the compound from its neat crystalline state to its neat liquid state. The free energy of this fusion transfer is usually called AG s (or if considered in the opposite direction). 

This chapter presents research on electrical potential oscillation across a liquid membrane from pharmaceutical and bioelectrochemical viewpoints. The mode of potential oscillation was found to change in response to drugs dissolved in one aqueous phase of this membrane and to be related to pharmacological activity. 

To explore the feasibility of these polymers as a pendant delivery drug delivery system, 5-fluorouracil activated by 1,1,1,3,3,3-hexamethyl disilazane was coupled to the phosphite via the Todd reaction as shown in Scheme 2. Briefly, the polymer (PPU-7) solution in dimethylacetamide was mixed with a 1 1 v/v solution of carbon tetrachloride and methylene chloride containing 0.5 volume percent of triethylamine (TEA) as catalyst. The activated drug dissolved in methylene chloride was added slowly into the mixture and allowed to react for 48 hours at room temperature. The product was isolated by precipitation into carbon tetrachloride. 

In deriving this equation, it was assumed that the drug dissolved uniformly from all surfaces of the... 

Figure 7 Rotating disk to evaluate the intrinsic dissolution rate of compounds. The amount of drug dissolving per unit area is the same everywhere on the disk surface. This simplification makes the disk a powerful experimental tool in drug discovery and development. 

This method can, in principle, be used to determine the transport characteristics of drugs dissolved or suspended in pharmaceutical gels. A potential problem with this method is the possibility for the gel to dissolve into the aqueous phase, with resulting disruption of the free boundary. These changing experimental conditions would lead to lack of precision for the experimental results and difficulty in interpreting them. 

In the first sections of the chapter, we begin with discussions of simpler systems, wherein typically only pure solid drug dissolves and then reacts with... 

The convective diffusion approach for weak basic drugs dissolving in acidic media was previously derived by Litt and Serad [9] and, as shown by McNamara and Amidon, could be applied to dissolution of the free base of papaverine. 

Moles of drug dissolved in the artificial membrane divided by total moles of drug (usually expressed as a percentage)... 

Intramuscular Route. The IM route is frequently used for drugs dissolved in oily vehicles or for those in a microcrystalline formulation that are poorly soluble in water (e.g., procaine or penicillin G). Advantages include rapid absorption (often in under 30 min), the opportunity to inject a relatively large amount of solution, and a reduction in pain and local irritation compared with SC injections. Potential comphcations include infections and nerve damage. The latter usually results from the choice of an incorrect site for injection. 

For soluble drugs, dissolve them in water and absorb into aquaphor base approximately double its quantity (for example, take 20 g of the base for a 10-mL liquid), and then mix in the intended base. 

The first difference is that non-cumulative data refer to amount of drug dissolved within a certain time period and not at a specific time point, i.e., in this case the observed variable is the amount dissolved, W(t, t2), between the time points t1 and t2 it2 > t ). Consequently, in contrast to their application to cumulative data (30) where the difference factor and the Rescigno index refer to area differences, for non-cumulative data these indices refer to the difference between the dissolved amount of the test and the reference product in a given time interval. 

The drug dissolved or dispersed in the melted lipid is poured into an aqueous emulsifier phase of the same temperature. By means of a rotor-stator homogenizer (e.g., an Ultra-Turrax), an o/w preemulsion is prepared and is then homogenized at high pressure and at a temperature at least 10°C above the melting point of the lipid. In most cases, nanoemulsion arises after only three to live homogenization cycles at 500 bar. Nanoparticles are formed by cooling the nanoemulsion to room temperature. 

Drug incorporation increases with type 1 and type 11 NLC because of a reduced or lacking crystalhnity, whereas drugs dissolve in oily nanocompartments located in the sohd matrix of type HI particles. The distinct advantage of NLC compared with SLN should be the higher drug loading capacity. 

Time Release/Sustained Release Capsules It is a useful solid dosage form of drug, where the particles of the drug dissolve at different time intervals. 

Unit/small dose Single dose drug dissolved in an aqueous solution, oral liquids Needs to be robust, easy to open and swallow. 

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