20.6f Elimination (start checking here)

excreted

Whether they are unchanged or metabolized before elimination, most medications (toxins and metabolites) are (?) in the urine.

expired air

Some are excreted in the feces or in (?).

renal excretion

Renal (?) occurs through two major processes: glomerular filtration and tubular secretion.

glomerular filtration pressure

Glomerular filtration is a function of (?), which in turn results from blood pressure and blood flow through the kidneys.

blood pressure and blood flow

Conditions that affect (?) can affect renal elimination.

proximal kidney tubules

Specialized transport systems in the walls of the (?) secrete medications into the urine.

active transport systems

These “pumps” are (?) and require energy in the form of adenosine triphosphate (ATP) to function.

specific chemicals

Some are specialized and transport only (?) whereas others can transport a range of similar chemicals.

toxicity

When medications compete for the same pump, (?) or other unwanted effects can result; however, combinations of some medications can take advantage of this specialization to prolong their circulation.

probenecid

For example, (?) blocks renal tubular pumps and competes for them with many antibiotics, among them penicillin, ampicillin, and oxacillin.

increase and prolong

Thus, probenecid is sometimes given with those antibiotics to (?) medication blood levels.

absorption

The same factors that affect (?) at any other site also affect reabsorption in the renal tubules.

urine pH

Of particular concern is the (?).

Lipid-soluble and non-ionized molecules

(?) are readily reabsorbed.

sodium bicarbonate

Changing the urine pH (usually by administering (?) to make it more alkaline) can affect the reabsorption in the renal tubules.

ionized

For example, if a medication becomes (?) in a more alkaline environment, making the urine more alkaline, interferes with reabsorption and causes more of the medication to be excreted.

expired air

Some medications and their metabolites can be eliminated in the (?).

breath test

This is the basis of the (?) that police use to determine a driver’s blood alcohol level.

Ethanol

(?) is released in the expired air in proportion to its concentration in the bloodstream.

exhalation

Although the liver degrades most ingested ethanol, (?) releases a measurable quantity.

feces

Medications also can be excreted in the (?).

enterohepatic circulation

In (?), if a medication (or its metabolites) is excreted into the intestines from bile, the body can reabsorb the medication and experience a sustained effect.

sweat, saliva, and breast milk

Additionally, medications can be excreted through (?).

sweat glands

Excretion through (?) is not commonly a significant mechanism for elimination.

mammary glands

Excretion through (?) becomes a concern when nursing mothers take medications.