How do ion traps work?
The ion trap functions as a mass spectrometer when the trapping field is changed, so that the trajectories of simultaneously trapped ions of consecutive specific mass/charge ratio become sequentially unstable, and ions leave the trapping field in order of mass/charge ratio.
What does it mean when a drug is ionized?
Ionized (or charged) drugs are not absorbed as efficiently as un-ionized drugs are. Practically speaking, this means that if taken orally, a drug that is a weak acid will be absorbed primarily in the acidic environment; whereas, a drug that is a weak base will be absorbed in the alkaline environment small intestines.
Are ions trapped in plasma membrane?
The negatively charged macromolecules or ions, usually chloride ions, cannot pass through the plasma membrane as they are too large to be moved in or out of the cell via the chloride channels. This is due to the channels being too large and bulky, hence anions remain trapped inside the cell.
What is ionized and unionized drugs?
Most drugs are weak acids or bases that are present in solution as both the ionized and unionized forms. Ionized molecules are usually unable to penetrate lipid cell membranes because they are hydrophilic and poorly lipid soluble. Unionized molecules are usually lipid soluble and can diffuse across cell membranes.
What is an RF trap?
A quadrupole ion trap is a type of ion trap that uses dynamic electric fields to trap charged particles. They are also called radio frequency (RF) traps or Paul traps in honor of Wolfgang Paul, who invented the device and shared the Nobel Prize in Physics in 1989 for this work.
How does quadrupole ion trap work?
10.6—quadrupole ion trap). Various voltages are applied to the electrodes to trap and eject ions based on their m/z. The ring electrode RF potential produces a 3D quadrupolar potential field within the trapping cavity, which traps ions in a stable oscillating trajectory that is confined within the trapping cell.
How does ion trapping affect drug distribution?
Ion trapping is the reason why basic (alkaline) drugs are secreted into the stomach (for example morphine), where pH is acidic, and acidic drugs are excreted in urine where the conditions are alkaline.
What is ionized vs unionized?
Ionized molecules are usually unable to penetrate lipid cell membranes because they are hydrophilic and poorly lipid soluble. Unionized molecules are usually lipid soluble and can diffuse across cell membranes.
What causes ion trapping?
In cell biology, ion trapping is the build-up of a higher concentration of a chemical across a cell membrane due to the pKa value of the chemical and difference of pH across the cell membrane.
What is ion trapping in drug absorption?
Ion trapping alters the urine pH to inhibit reabsorption of toxins across the renal tubular membranes. The principle behind this approach is to “trap” the toxin in its ionized form in the urine where it can be excreted.
Is aspirin ionized in the stomach?
Aspirin was not absorbed by the stomach at pH 6.5. These experiments indicate that aspirin can be absorbed to an appreciable extent in its ionized form by the small intestine but not by the stomach.
Are ionized or unionized drugs absorbed?
The ionized portion is charged, which attracts water molecules, thus forming large complexes. These complexes cannot cross the membranes because they are less lipid soluble. This is why the ionized part of the drugs cannot cross the membrane. Drugs are better absorbed in unionized form.
Which is an ion trapping agent in urine?
Alkaline urine favors the ionization of acidic compounds, and acidic urine favors the ionization of alkaline compounds. Toxins that are amenable to ion trapping are mostly weak acids and weak bases. Ammonium chloride can be used to promote urinary acidification.
Why is ion trapping important in pharmacokinetics?
Pharmacokinetics. Ion trapping is also important outside of pharmacology. For example, it causes weakly acidic hormones to accumulate in the cytosol of cells. This is important in keeping the external concentration of the hormone low in the extracellular environment where many hormones are sensed.
When does ion trapping need to be contraindicated?
Ion trapping is contraindicated when the toxicant has a large volume of distribution, is strongly protein bound, is highly lipid soluble, and is cleared primarily by tissue or hepatic metabolism. Ion trapping alters the urine pH to inhibit reabsorption of toxins across the renal tubular membranes.
How does sodium bicarbonate and amphetamine affect ion trapping?
Similarly, ingesting sodium bicarbonate with amphetamine, a weak base, causes better absorption of amphetamine (in stomach) and its lesser excretion (in urine), thus prolonging its actions. Ion trapping can cause partial failure of certain anti-cancer chemotherapies. Ion trapping is also important outside of pharmacology.