Gastrointestinal retentive

Technologies to increase gastrointestinal retention time Technologies to improve drug release mechanisms of oral preparations Adjuvants to enhance absorption Methods of increasing bioavailability of drugs Penetration enhancement Improved dissolution rate... 

The Class I agents have many similar side effects and toxicities. The anticholinergic side effects include dry mouth, constipation, and urinary hesitancy and retention. Common gastrointestinal (GI) side effects include nausea, vomiting, diarrhea, and anorexia. Cardiovascular adverse effects are hypotension, tachycardia, arrhythmias, and myocardial depression, especially in patients with congestive heart failure. Common central nervous system (CNS) side effects are headache, dizziness, mental confusion, hallucinations, CNS stimulation, paraesthesias, and convulsions. 

Adverse reactions of amantadine include gastrointestinal upset with nausea and vomiting, anorexia, asthenia (weakness, loss of strength), constipation, depression, visual disturbances, psychosis, urinary retention, and orthostatic hypotension. 

These dragp are used with caution in patients with tachycardia, cardiac arrhythmias, hypertension, hypotension, those with a tendency toward urinary retention, those with decreased liver or kidney function, and those with obstructive disease of the urinary system or gastrointestinal tract. The anticholinergic drugp are given with caution to the older adult. 

Symptoms of left-sided heart failure include dyspnea, orthopnea, and paroxysmal nocturnal dyspnea (PND), whereas symptoms of right-sided heart failure include fluid retention, gastrointestinal bloating, and fatigue. 

Patients at increased risk of NSAID-induced gastrointestinal adverse effects (e.g., dyspepsia, peptic ulcer formation, and bleeding) include the elderly, those with peptic ulcer disease, coagulopathy, and patients receiving high doses of concurrent corticosteroids. Nephrotoxicity is more common in the elderly, patients with creatinine clearance values less than 50 mL/minute, and those with volume depletion or on diuretic therapy. NSAIDs should be used with caution in patients with reduced cardiac output due to sodium retention and in patients receiving antihypertensives, warfarin, and lithium. 

Fig. 17. Biological model recommended for describing the uptake and retention of cerium by humans after inhalation or ingestion. Numbers in parentheses give the fractions of the material in the originating compartments which are cleared to the indicated sites of deposition. Clearance from the pulmonary region results from competition between mechanical clearances to the lymph nodes and gastrointestinal tract and absorption of soluble material into the systemic circulation. The fractions included in parentheses by the pulmonary compartment indicate the distribution of material subject to the two clearance rates however, these amounts will not be cleared in this manner if the material is previously absorbed into blood. Transfer rate constants or functions, S(t), are given in fractions per unit time. Dashed lines indicate clearance pathways which exist but occur at such slow rates as to be considered insignificant compared to radioactive decay of the cerium isotopes.

Sagan, C. E. and Lengemann, F. W. (1973). The retention and movement of cerium-141 in the gastrointestinal tract of adult rats irradiated with 800 R and fed grain-based or milk diets, Radiat. Res. 53,480. 

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