Reasons given for this low rate of screening include physicians', patients' and health care providers' reluctance to encourage, receive, or pay for these procedures.
These “preps”, consisting of 4 L of solution, are generally uncomfortable for the patient to complete.
They often complain of a sense of fullness,
nausea, cramping, and
vomiting, sometimes of such magnitude that they do not complete the prescribed
regimen.
What the patient perceives as the most comfortable preparation
regimen may not yield an adequately cleansed colon.
In many cases, patients do not comply with preparation regimens that the patients feel are too inconvenient or too uncomfortable.
In addition, many preparations may
pose a
health risk, as they cause fluid and
electrolyte disturbances in the body, which are known to be harmful, even deadly, in some patients.
The large volume required for effective use of this type of formulation for lavage is frequently associated with distention,
nausea, cramping,
vomiting, and significant patient discomfort.
Thus, while these formulations are generally effective, they are not well tolerated.
Without close supervision, many patients do not take the complete course of preparation.
However, because of their small volumes, when used in this fashion they do not sufficiently clean the colon for diagnostic or
surgical procedures.
Also these small volume preparations do not contain
polyethylene glycol.
Another drawback of these prior art preparations is their unpleasant, bitter,
saline taste.
It is difficult to overcome this unpleasant taste, even the most common natural sweeteners such as glucose,
fructose, saccharose, and
sorbitol could change the osmolarity of these orally administered solutions resulting in potentially dangerous
electrolyte imbalances.
Although, the formula for this
drug was modified to improve the
flavor of the solution, many patients have expressed a dislike for the large volumes that must be ingested.
Generally, these attempts produced improved patient symptoms but reduced the quality of the
colonoscopy below acceptable standards.
However, it is not clear how well these two treatments cleansed the bowel in comparison to the standard 4 liters of lavage solution alone.
However, patients who received the bisacodyl plus 2 liters of GoLYTELY, but were not restricted to liquids for more than 30 hours before examination, did not have satisfactory preparation.
Other studies have failed to find a good combination of physician and patient assessments when a laxative is used in conjunction with a reduced lavage volume.
Thus, despite others' attempts, improved patient symptoms do not necessarily follow the use of reduced volumes of lavage fluids with laxative pretreatment.
Nor does the combination reliably produce a colon preparation that is as good as that achieved when a large volume lavage solution is used.
Furthermore, the attempts to cleanse the colon with a smaller volume of a lavage solution in combination with a laxative have made the patients and physicians engage in protracted fasting and a cumbersome schedule for the preparation.
As noted above, what we have found is that prior attempts to obtain at the same time both an
adequate preparation and improved
patient comfort have failed because they overlooked key parameters in the dosing of the patients, namely, the duration of time between laxative and lavage
ingestion and the effect of the laxative prior to the lavage.
From the foregoing, it can be seen that the two approaches to colonic lavage that have been used in the past have significant drawbacks that have not been resolved by prior attempts.
The
isotonic solutions, while not causing clinically significant fluid or electrolyte shifts, are, of necessity, of large volume, and difficult for patient
ingestion.
The hypertonic solutions or concentrated non-aqueous formulations are sometimes inadequate to prepare the colon and more importantly, can cause clinically significant electrolyte and fluid shifts, which have been known to cause deaths.
In the nearly 20 years since the advent of large volume colonic lavage solutions, there has not been success in discovering an effective small volume gastrointestinal cleansing preparation that minimized fluid or electrolyte shifts.
Concentrating the large volume lavages into smaller volumes does not achieve the same effectiveness, and is not as safe.
This is because the components are not soluble in the small volumes necessary and because the concentrations are such that dangerous electrolyte shifts could occur.
Available methods for cleansing a colon are not optimally tolerated by patients, and have potentially dangerous side effects.