Omotically active compounds (osmotics) are used widely in pharmacy and medicine. For example, osmotics are used to adjust the tonicity of drugs, in particular parenteral medications, where the osmotic pressure of a drug is adjusted to be hypotonic, hypertonic or isotonic, depending on how it is administered. For example, the osmotic pressure of a parenteral drug solution may be adjusted to match the osmotic pressure of human blood by adding an osmotic agent (isosmotic solutions).
Furthermore, osmotics are used in dialysis therapy, in particular in peritoneal dialysis, to withdraw excess water from the dialysis patient.
The peritoneal dialysis method is based on the fact that a solution containing osmotically active compounds is introduced into the abdominal cavity of a dialysis patient through a catheter. The solution is left in the patient's abdominal cavity, where it manifests its osmotic effect for a certain period of time (usually a few hours). In other words, endogenous water is withdrawn from the patient into the abdominal cavity. After a certain dwell time, the peritoneal dialysis solution, which is then dilute, is drained out through a catheter.
This principle is employed in various methods of peritoneal dialysis therapy. For example, the methods of intermittent peritoneal dialysis (IPD), nocturnal intermittent peritoneal dialysis (NIPD), continuous cyclic peritoneal dialysis (CCPD) or continuous ambulant peritoneal dialysis (CAPD) may be employed as needed. In IPD, NIPD and CCPD, instruments which support the patient in performing the peritoneal dialysis method are used. CAPD is a manual method.
By adding osmotically active compounds, it should be ensured in particular that the osmotic pressure of the peritoneal dialysis solution is high enough during the entire dwell time in the abdominal cavity to withdraw water from the patient. In other words, water goes from the patient's circulation into the abdominal cavity (ultrafiltration).
However, because of the transfer of water into the abdominal cavity, dilution of the peritoneal dialysis solution introduced there necessarily occurs. As a result of this dilution, there is a decline in the concentration of the osmotically active compound and thus also the osmotic pressure of this solution.
If the osmotic pressure of the peritoneal dialysis solution drops because of this dilution, this in turn results in a decrease in or even a complete standstill of the transfer of water into the abdominal cavity per unit of time. In these cases, there is no longer an effective withdrawal of water with advancing dwell time of the peritoneal dialysis solution in the patient's abdominal cavity.
Through absorption of osmotically active compounds into the patient's bloodstream, the direction of the transfer of water may even be reversed, i.e., water goes from the abdominal cavity into the patient's bloodstream (negative ultrafiltration). This is the case when the dilute peritoneal dialysis solution in the abdominal cavity has a lower osmotic pressure than the patient's endogenous water (e.g., blood).
By adding suitable osmotically active compounds to the peritoneal dialysis solution, the osmotic pressure may be maintained for a treatment time, which is suitable for peritoneal dialysis, so that there is no excessive decline in ultrafiltration within the dwell time of the solution in the abdominal cavity. A negative ultrafiltration is thus also largely prevented.
The solutions used in the peritoneal dialysis therapy usually contain sugar monomers or polymers, for example, glucose or polyglucose (e.g., starch derivatives) as osmotically active compounds.
U.S. Pat. No. 4,889,634 relates to a peritoneal dialysis solution containing hydroxypropyl-β-cyclodextrin.
JP 8071146 relates to a peritoneal dialysis solution containing α- or γ-cyclodextrin, 2-hydroxyethyl ether, 2-hydroxypropyl ether, 6-O-α-glucosyl or 6-O-α-maltosyl derivatives of α-, β- and γ-cyclodextrin.
However, the state of the art describes cyclodextrin compounds which are not selectively substituted. Instead these cyclodextrin derivatives are mixtures of a wide variety of compounds (different degrees of substitution, different positional isomers) because the substitution of cyclodextrins takes place selectively on certain hydroxyl groups of the cyclodextrins only to a very limited extent.