Intravenous injection disadvantage

Subcutaneous injections usually have a lower rate of absorption and slower onset of action than intramuscular or intravenous injections. The rate of absorption may be enhanced by infiltration with the enzyme hyaluronidase. Disadvantages of subcutaneous injection are as follows ... 

Review the advantages and disadvantages of oral administration and intravenous injection of drugs. 

A serious practical disadvantage is the need to administer the DTPA intravenously by slow injection, or by infusion for maximum effectiveness. This requirement may delay the start of treatment if no qualified person is immediately available to give an intravenous injection. Further, experience has shown that the treatment needs to be continued for many months or years long-term intravenous treatment may be unpleasant for the patient, and is quite demanding on medical resources. Thus there has been considerable interest in the possibilities of the other routes of treatment. For continuation therapy, after the first few weeks, oral treatment would be very useful. The... 

The most commonly used chelation therapy agents in the United States today are EDTA and DMSA (or succimer). In addition, penicillamine (PCA) and BAL are used to chelate lead. Each of these agents has numerous disadvantages, ranging from undesirable methods of delivery (intramuscular injection of BAL and intravenous delivery of EDTA), to unpleasant side effects (typically nausea and vomiting), to chelation and increased excretion of necessary metals (e.g., iron and zinc) (Table XIX) (17, 207, 525). 

Measurement of fecal excretion of isotopic bile acids (65) gives only the half-life of the labeled bile acid used. The isotope is injected intravenously, and the daily fecal excretion of radioactivity is measured. According to this procedure, the fractional excretion rate of cholic acid in man is normally about 12-13% per day (66,67). Disadvantages of the method are that the absolute values are not obtained, the cholic and chenodeoxycholic acid excretions must be measured separately or a double label method must be used, and the fecal flow should be regular, though an unabsorbable fecal marker can be used. The method appears to be suitable for screening of ileal dysfunction. 

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