Good day everyone. This is week 4 of your pharmacology class. We'll have pharmacokinetics phase. In pharmacokinetics phase, we're talking about medications.
They are given to achieve desirable effects in the body and to produce this effect, the drug must reach its target cells. For some medications, such as tropical agents used to treat superficial skin conditions, this is a relatively simple task. For others, however, the process of reaching target cells in sufficient quantities to produce a physiological change may be challenging. Drugs are exposed to a myriad of different barriers and destructive. processes after they enter the body.
For your learning outcomes, after reading this chapter or this chapter of lesson, the student should be able to explain the application of pharmacokinetics to clinical practice, identify the four components of your pharmacokinetics, explain how substances travel across Plasma membranes. Discuss also factors affecting drug absorption. Explain the metabolism of drugs and its applications to pharmacotherapy.
Students must be able to discuss how drugs are distributed throughout the body and how the plasma proteins affect drug distribution. Also, the major processes by which drugs are excreted and the applications of drugs onset peak and plasma half-life or t and one half two duration of pharmacotherapy we also have the differentiation of loading and maintenance doses. Now, pharmacokinetics, the term is derived from the root word pharmako, which means medicine, and kinetics, which means movement or motion. Pharmakokinetics is thus the study of drug movement throughout the body. In practical terms, it describes how the body deals with medications.
Pharmacokinetics is a core subject in pharmacology and a firm grasp of this topic allows the nurse to better understand and predict the actions and side effects of medications in patients. Drugs face numerous obstacles in reaching their target cells. For most medications, the greatest barrier is crossing the many membranes.
that separate the drug from its target cells. A drug taken by mouth, for example, must cross the plasma membranes of the mucosal cells of the gastrointestinal tract and the capillary endothelial cells to enter the bloodstream. To leave the bloodstream, the drug must again cross capillary cells, travel through the interstitial fluid, And depending on the mechanism of action, the drug may also need to enter target cells and cellular organelles such as the nucleus, which are surrounded by additional membranes.
These are examples of just some of the barriers that a drug must successfully penetrate before it can produce a response. While moving toward target cells, and passing through the various membranes, drugs are subjected to numerous physiological processes. For medications given by the enteral route, stomach acid and digestive enzymes often act to break down the drug molecules. Enzymes in the liver and other organs may chemically change the drug molecule to make it less active.
Now, if the drug is seen as a foreign object by the body, phagocytes may attempt to remove it or an immune response may be triggered. The kidneys, the large intestine, and other organs attempt to excrete the medications from the body. Now, these examples will illustrate pharmacokinetic processes, how the body handles medications.
Now, the many processes of... Pharmacokinetics are grouped into four categories. We have your absorption, distribution, metabolism, and excretion. For your pharmacokinetics phase, we have your actual medication.
It is a solid form, either tablet or capsule, which must be dissolved and changed into its liquid form. Wherein in the pharmacokinetic phase, you'll have the absorption or the first pass effect. Distribution, wherein they are connected to protein binding receptors. Then you have your metabolism, wherein there will be the onset, the peak, and the duration.
Excretion will depend on the half-life of the medication. The pharmacodynamic phase will then be the part wherein the receptors will either be the agonist or the antagonist. Pharmacokinetics is the movement and modification of a drug.
Again, once it is administered, it will be absorbed by the body, distributed in the different parts that would need it. It will be metabolized and used by the cells and then eliminated once they have reached their destination and have done their job. Dissolution is the process in which a substance forms. A solution. This solution testing measures the extent and rate of the solution formation from a dosage form such as tablet, capsule, and ointment.
Now, the dissolution is an important part for its bioavailability and therapeutic effectiveness of the drug. For your pharmacokinetics, we're talking about the four stages. Again, the absorption, distribution, metabolism, and excretion. Remember, drugs are needed by the body physiologically and both as a substance also to have its effect when it is administered to the body. Pharmacodynamics will be the actual processes of your medications, how the body would handle the medications and how they would react on the administered medications in the body.
Now we have the first phase of drug action which is dissolution wherein it is the ability and the responsibility of the gastrointestinal tract or other parts of our body that would change the solid types of oral medications from tablet will be disintegrated and form into a dissolution. They will be changed into small particles to dissolve into its liquid form. Second phase of dissolution, again, we have your breaking down disintegrated into fine particles.
The fine particles will then be changed into a solution. It will depend on the type of medication. It could be slow acting or slow rate of drug dissolution. It will be medium acting or has a moderate rate.
of drug dissolution and it could also be a fast rate of drug dissolution. It could be due to the increase in the surface area where it is processed by the body. Excipients, we're talking about tablets not being 100% as a drug. We're talking about certain fillers and certain substances that are inert that are are Provided so that the drug will have its particular size and shape.
And these fillers or excipients are useful in either enhancing the drug for your dissolution or it will help out with the shape of the drug so that it may be able to have its capability to have a form and shape. Now it could be and must be stable and reproducible. No unwished interaction with the drug or no negative effects with the drug.
It should be inert. It should have its desired functionality or uses. And of course, cost-effective, wherein not only do we need the actual medication, but these shape-formers would help us in having the actual medication have its shape. What are the factors that would affect the dissolution?
We have either liquid or solid form. Remember that liquids... are already in its fluid form wherein it will be readily absorbable by the body as compared to the solid form wherein they must be disintegrated and formed into a solution now for the gastric pH acidic media will faster will have faster disintegration and absorption.
Remember that for the normal gastric pH in your stomach, it ranges from 1.5 to 3.5 pH. For your young and elderly, they will have increased pH but decreased absorption rate because of the hyperacidity that may happen during the time that they have taken in different forms of medications. Please remember the enteric coated drugs. They are not easily disintegrated in the acidic environment. however when they are in the intestine they'd be able to disintegrate wherein they would be able to react with the alkalinic environment please take note that they should not be crushed always check your medications as a nurse if the medications that you are administering to the different patients are either in dairy-coated or just regular drugs. Enteric coated are shiny in its form and shape and in its current state.
And always remember also the amount of food that is present in the stomach of the patient or currently present. interfere with the dissolution phase and absorption phase for it will stay longer in the stomach of the patient and it will take longer time to be able to be absorbed by the body after absorption of oral drugs from the gastrointestinal tract They pass from the intestinal lumen to the liver through the portal vein. In the liver, some drugs are metabolized to an inactive form and are excreted, therefore reducing the amount of active drug available to exert a pharmacological effect. This is referred to as the first pass or first pass metabolism.
Most oral drugs are affected to some degree by first pass metabolism. Lidocaine And some nitroglycerins, for example, are not given orally because they have extensive first-pass metabolism. And most of the drug is inactivated. Drugs that are delivered by other routes, either through intravenous or intramuscular or subcutaneous, They could be given through nasal.
Also, through sublingual and buccal, they do not enter the portal circulation and are not subjected to the first pass metabolism. When we talk about bioavailability, it refers to the percentage of administered drug available for activity. For orally administered drugs, bioavailability is affected by absorption and first-pass metabolism. The bioavailability of oral drugs is always less than 100% and it varies based on the rate of first-pass metabolism. The bioavailability, for example, of the medication.
Rosovastatin is 20%, whereas the bioavailability of digoxin ranges from 70% to 85%. Now, the bioavailability of intravenous drugs is 100%. Factors that could alter bioavailability would include, Number one. the drug form such as tablet, capsules, sustained release bids, liquid form, transdermal patch, suppository, or inhalation.
Number two, the route of administration. They could be enteral, topical, or parenteral in nature. Number three, the gastric mucosa and the motility.
Number four, talking about administration with food and other drugs. Number five would be changes in liver metabolism caused by liver dysfunction or inadequate hepatic blood flow. Now, a decrease in liver function or a decrease in the hepatic blood flow can increase the bioavailability of a drug.
but Only if the drug is metabolized by the liver. Less drug is destroyed by hepatic metabolism in the presence of a liver disorder. Now again, the processes of your body.
We are always talking about the absorption of the medication. Then, how it will be distributed, the metabolism entering the liver through the portal vein, and then excretion, the proper elimination of the medication. Absorption is a process involving the movement of a substance from its site of administration across body membranes to circulating fluids.
Drugs may be absorbed through the skin and associated mucous membranes or they may move across membranes that line the gastrointestinal or respiratory tract. Most drugs, with the exception of a few topical medications, intestinal anti-infectives, and some radiologic contrast agents, must be absorbed to produce an effect. Absorption is the primary pharmacokinetic factor determining the length of time it takes a drug to produce its effect. In order for a drug to be absorbed, it must dissolve. Now, the rate of dissolution determines how quickly the drug disintegrates and disperses into simpler forms.
Therefore, drug formulation is an important factor of bioavailability. In general, the more rapid the dissolution, the faster the drug absorption and the faster would be the onset of drug action. Now, for example, L-famotidine, administered as an orally disintegrating tablet, dissolves within seconds and after being swallowed is delivered to the stomach where it blocks acid secretion from the stomach, thereby treating conditions of excessive acid secretion. At the other extreme, some drugs have shown good results.
clinical response as slowly dissolving drugs such as leothyronine sodium and thyroxine administered for resolution of hypothyroid symptoms. In some instances, it is advantageous for a drug to disperse rapidly. In other cases, it is better for the drug to be released slowly where the effects are more prolonged.
for positive therapeutic benefit. Absorption is conditional on many factors. Drug in elixir or serum formulation are absorbed faster than tablets or capsules.
Drug administered in high doses are generally absorbed more quickly and they have a more rapid onset of action. than those given in low concentrations. Now, the speed of digestive motility, surface area, pH, lipid solubility, exposure to enzymes in the digestive tract, and blood flow to the site of drug administration also affect absorption.
Because drugs administered... Through IV, directly enter the bloodstream, absorption to the tissues after the infusion is very rapid. Intramuscular medications would take longer to absorb. And other factors that influence the absorption of medical drugs include the following. First, you have your drug formulation and dose.
Second, the size of the drug molecule. Third, surface area of the absorptive site. Next, the digestive motility or blood flow. Next is the lipid solubility. Then we have the degree of ionization.
And then we have your acidity or alkalinity, which is the power of hydrogen or pH. You also have interactions with food and other medications. The degree of ionization of a drug also affects its absorption. A drug's ability to become ionized depends on the surrounding pH. Aspirin provides an excellent example of the effects of ionization on absorption. In the acid environment of the stomach, aspirin is in its non-ionized form and thus readily absorbed and distributed by the bloodstream. As aspirin enters the alkaline environment of the small intestine, however, it becomes ionized.
In its ionized form, aspirin is not as likely to be absorbed and distributed. to target cells unlike acidic drugs medications that are weakly basic or weak basic forms are in their non-ionized form in an alkaline environment therefore basic drugs are absorbed and distributed better in alkaline environments such as in the small intestine The pH of the local environment directly influences drug absorption through its ability to ionize the drug. In simplest term, it may help the nurse to remember that acids are absorbed in acids.
Bases are absorbed in bases. Drug-to-drug or food-to-drug interactions may influence absorption. Main examples of these interactions have been discovered.
Now, for example, administering tetracycline with food. or drugs containing calcium, iron, or magnesium can significantly delay absorption of the antibiotic. High-fat meals can slow the stomach motility significantly and delay the absorption of oral medications taken with the meal.
Dietary supplements may also affect absorption. Common ingredients in herbal weight loss products such as your aloe leaf, guar gum, senna, and your yellow duck exert a laxative effect that may decrease intestinal transit time and reduce drug absorption. As nurses, nurses must be aware of drug interaction and advise patients to avoid.
known combination of food and medications that significantly affect drug action. Now, your pharmacokinetic variables depend on the ability of a drug to cross plasma membranes, with few exceptions, of course. Drugs must penetrate these membranes to produce their effects and like other chemicals, drugs primarily use two processes to cross the body membranes.
We first have your active transport. This is movement of a chemical against a concentration or electrochemical gradient. Co-transport involves the movement of two or more chemicals across the membrane.
Diffusion or passive transport, this is a movement of a chemical from an area of higher concentration to an area of lower concentration. Plasma membranes consist of a lipid bilayer with protein and other molecules interspersed in the membrane. This lipophilic membrane is relatively impermeable. to large molecules ions and polar molecules these physical characteristics have direct application to pharmacokinetics for example drug molecules that are small non-ionized and lipid soluble will usually pass through plasma membranes by simple diffusion and more easily reach their target cells.
Small water-soluble agents such as urea, alcohol, and water can enter these pores in the plasma membrane. Large molecules, ionized drugs, and water-soluble agents, however, will have more difficulty crossing plasma membranes. Remember that these agents may use other means to gain entry such as protein carriers or active transport. Drugs may not need to enter the cell to produce their effects. Once bound to receptors located on the plasma membrane, some drugs activate a second messenger within the cell, which produces the physiological change.
In here, you have your diffusion. It could be active or passive form. It could be facilitated diffusion also, which is a passive type of transport. For your active transport, you would be needing energy in order to have the medications enter the cell.
The following are the factors affecting the drug absorption. Solubility or drug solubility, they pass readily through the gastrointestinal membrane. While your water soluble drugs, they need an enzyme or protein for them to be able to enter the gastrointestinal membrane.
Local condition or site of absorption, we need weak acids. Less ionized in the stomach, they readily pass through the small intestine. There are factors also such as pain, stress, solid food or fatty food or sometimes hot food.
They slow down the gastric emptying time. Distribution, on the other hand, involves the transport of drugs through the body. The simplest factors determining distribution is the amount of blood to body tissues. The heart, the liver, the kidneys, and the brain receive the most blood supply.
The skin, the bone, and adipose tissues receive a lower blood supply. Therefore, it is more difficult to to deliver high concentrations of drug to these areas. The physical properties of the drug greatly influence how it moves throughout the body after administration.
Lipid solubility is an important characteristic because it determines how quickly a drug is absorbed. Mixes within the bloodstream crosses the membranes and becomes localized in body tissues. Lipid-soluble agents are not limited by the barriers that normally stop water-soluble drugs, so they are more completely distributed to body tissues. Some tissues have the ability to accumulate and store drugs after absorption.
The bone marrow, the teeth, the eyes, and adipose tissues, they have an especially high affinity or attraction for certain medications. Examples of agents that are attracted to adipose tissues are theopentyl, diazepam, and lipid-soluble vitamins. tetracycline an antibiotic, binds to calcium salts and accumulates in the bones and teeth. Once stored in tissues, drugs may remain in the body for many months and are released very slowly back to the circulation. Not all drug molecules in the plasma will reach their target cells because many drugs bind reversibly.
to plasma proteins particularly albumin to form drug protein complexes drug protein complexes are too large to cross capillary membranes therefore the drug is not available for distribution to body tissues drugs they are bound to protein proteins circulate in the plasma until they are released or displaced from the drug protein complex. Only unbound or free drugs can reach their target cells or be excreted by the kidneys. Some drugs such as the anticoagulant warfarin are highly bound. 99% of the drug in the plasma is bound in drug protein complexes and is unavailable to reach target cells.
Drugs and other chemicals compete with one another for plasma protein binding sites and some agents, they have a greater affinity for those binding sites than other drugs. Drug-to-drug and drug-to-food interactions may occur when one drug displaces another from plasma proteins. The displaced medication can immediately reach high levels in the bloodstream and produce adverse effects. Drugs such as aspirin or valproates, for example, displace comodin from the drug protein complex, thus raising blood levels for free comodin and dramatically enhancing the risk of hemorrhage.
Most drug guides or most drug guides would give the percentage of medication bound to plasma proteins. When giving multiple drugs that are highly bound, the nurse should monitor the patient closely for adverse effects. We have protein-binding drugs wherein they could cross the plasma in the extracellular water. The albumin would have the drug or through protein, the drug would be bound or unbound, exchanging the drugs through the different protein binding processes. The plasma, the interstitial and lymph fluids, and tissues and other Body water could bind or free the different medications and they could exchange these medications in order to circulate the different drugs in the body.
Remember for your factors affecting the distribution, the organ size, the flow of the blood, and The solubility of the medication wherein lipid soluble drugs can also cross the blood-brain barrier so that it may enter the brain. Metabolism, also called biotransformation, is the process of chemically converting a drug to form or to a form that is usually more easily removed from the body. Metabolism involves complex biochemical pathways and reactions that alter drugs, nutrients, vitamins, and minerals. The liver is the primary site of drug metabolism, although the kidneys and cells of the intestinal tract also have high metabolic rates. Medications, they undergo many types of biochemical reactions as they pass through the liver, including hydrolysis, oxidation, and reduction.
During metabolism, the addition of side chains known as conjugates makes drugs more water-soluble and more easily excreted by the kidneys. Most metabolism in the liver is accompanied by the hepatic microsomal enzyme system. This enzyme complex is sometimes called the P450 system, named after cytochrome, which is a key component of the system.
As they relate to pharmacotherapy, the primary actions of the hepatic microsomal enzymes are to inactivate drugs and accelerate their excretion. In some cases, however, metabolism can produce a chemical alteration that makes the resulting molecule more active than the original. For example, the narcotic analgesic codeine undergoes biotransformation to morphine, which has significantly greater ability to relieve pain.
In fact, some agents known as prodrugs have no pharmacologic activity unless they are first metabolized to their active form by the body. Examples of prodrugs include Benazepril and Losartan. Changes in the function of the hepatic microsomal enzymes can significantly affect drug metabolism. A few drugs have the ability to increase metabolic activity in the liver, a process called enzyme induction.
For example, phenobarbital causes the liver to synthesize more microsomal enzymes. By doing so, phenobarbital increases the rate of its own metabolism as well as that of other drugs metabolized in the liver. In these patients, higher doses of medication may be required to achieve the optimum therapeutic effect.
Certain patients have decreased hepatic metabolic activity which may alter drug action. Hepatic enzyme activity is generally reduced in infants and elderly patients. So. Pediatric and geriatric patients are more sensitive to drug therapy than middle-aged patients.
Patients with severe liver damage such as that caused by cirrhosis will require reductions in drug dosage because of the decreased metabolic activity. Certain genetic disorders have been recognized in which patients. patients lack specific metabolic enzymes. Drug dosages in these patients must be adjusted accordingly. The nurse should pay careful attention to laboratory values that may indicate liver disease so that doses may be adjusted.
Metabolism has a number of additional therapeutic consequences. Drugs absorbed after oral administration would cross directly into the hepatic portal circulation, which carries blood to the liver before it is distributed to other body tissues. Thus, as blood passes through the liver, circulation or liver circulation Some drugs can be completely metabolized to an inactive form before they are able to reach the general circulation.
This first-class effect is an important mechanism since a large number of oral drugs are rendered inactive by hepatic metabolic reactions. Alternate routes of delivery that bypass the first pass effect would be your sublingual, the rectal, or the parenteral routes. They may need consideration for these drugs.
For your first pass effect or first pass metabolism, we are talking about the gastrointestinal tract. It will enter the intestinal lumen. And then the liver.
Some drugs, they could be metabolized to become active. And then they would be excreted, reducing the amount of active drugs in the body. For your first-pass effect or first-pass metabolism, we're talking about the liver enzymes, which are which is your cytochrome P450 system.
It converts drugs to metabolites. Then you have your decreased drug metabolism rate resulting to excess drug accumulation that can lead to toxicity. Also have your drug half-life.
It is the time it takes for the amount of drug in the body to be reduced by the half amount. when it was delivered. Now, for example, for us to understand your half-life, we'll have your ibuprofen.
It has a half-life of about 2 hours. If the patient uses or takes 200 mg, after 2 hours, half of the drug amount will be gone. We're in 100 milligrams to the left. Two hours later, 50 milligrams or half of the 100. Another 2 hours would pass, you'll have 25 mg. And another 2 hours, you'll have 12.5 mg.
And more 2 hours later, 6.25 mg will be left up until the drug is completely absorbed. By knowing the first or knowing the half-life, You'll be able to reach a steady state or the plateau of the drug level. It can be identified.
It can be achieved when the amount of drug given is the same as the amount that is removed from the body. Then you have... the state or a steady state of drug concentration this is needed to have optimal therapeutic benefit now remember your half-life it takes for a half of the drug concentration to be removed from the body for a short type of medications You have 4 to 8 hours.
It is given several times a day. It has a range of only, again, 4 to 8 hours. Such as your penicillin G, which is an antibiotic. Then for your long-term type of medications of 12 hours or more than 12 hours, the half-life would be...
determined by either actual 12 hours or more than 12 hours. It could be given twice a day or just once a day, such as your digoxin. Other sites of metabolism, you have your plasma, the kidneys, and the different membranes or the membranes of your intestine.
Here are some factors affecting biotransformation. Of course, your genes. Some would have fast metabolism. Others would have slower metabolism.
Physiologically, if you have liver disease, it will take some time for the body to be able to absorb the medication. The infants. Since their body is still developing, they would have decreased drug metabolism. For elderlies, since they are too old, if the patient has enlarged liver, problem with the blood flow. Different or differences in the production of the enzyme, it could slow down the metabolism.
Smoking, it directly affects the rate of metabolism of some drugs and prolonged illness. Surgery and the current illness would also slow down the absorption of the drugs. For your drug excretion, drugs are removed from the body by the process of excretion.
The rate at which medications are excreted determines the concentration of the drugs. in the bloodstream and tissues. This is important because the concentration of drugs in the bloodstream determines their duration of action.
Pathologic states such as liver disease or renal failure often increases the duration of drug action in the body because they interfere with the natural excretion mechanisms. Dosing regimens must be carefully adjusted in these patients. Although drugs are eliminated from the body by numerous organs and tissues, The primary site of excretion is the kidney. In an average-sized person, approximately 180 liters of blood is filtered by the kidney each day.
Free drugs, water-soluble agents, electrolytes, and small molecules are easily filtered at the glomerulus. Proteins, blood cells, conjugates, and drug protein complexes are not filtered because of their large size. After filtration at the renal corpuscles or corpuscle, chemicals and drugs are subjected to the process of reabsorption in the renal tubule.
Mechanisms of reabsorption are the same as absorption elsewhere in the body. Non-ionized and lipid-soluble drugs would cross renal tubular membranes easily and return to the circulation. Ionized and water-soluble drugs generally remain in the filtrate for excretion.
There are many factors that can affect drug excretion. These include the following. You have liver or kidney impairment. You have the blood flow of the patient, the degree of ionization of the medication, the solubility of the lipid, drug protein complexes, metabolic activity of the body, the acidity or the alkalinity of the intestines, and the gastrointestinal tract, or even the blood. Respiratory, glandular, or biliary activity.
Drug protein complexes and substances too large to be filtered at the glomerulus are sometimes excreted into the distal tubule of the nephron. For example, only 10% of a dose of penicillin G is filtered at the glomerulus. 90% is secreted into the renal tubule. As with metabolic enzyme activity, secretion mechanisms are less active in infants and older adults. Certain drugs may be excreted more quickly if the pH of the filtrate changes.
Weak acids such as aspirin are excreted faster. When the filtrate is slightly alkaline or alkaline. Now, because aspirin is ionized in an alkaline environment, the drug will remain in the filtrate and be excreted in the urine.
Weak basic drugs such as diazepam are excreted faster with the slightly acidic filtrate. Because they are ionized, in this environment. This relationship between pH and drug excretion can be used to advantage in critical care situations. Now, to speed the renal excretion of acidic drugs such as aspirin in an overdose patient, an order may be written to administer sodium bicarbonate. Sodium bicarbonate will make the urine more basic, which ions more aspirin, causing it to be excreted more readily.
Or ionizes, sorry, more aspirin, causing it to be excreted more readily. The excretion of diazepam, on the other hand, can be enhanced by giving ammonium. chloride this will acidify the filtrate and increase the excretion of diazepam Impairment of QD functions can dramatically affect pharmacokinetics.
Patients with renal failure will have diminished ability to excrete medications and may retain drugs for an extended time. Doses for these patients must be reduced to avoid drug toxicity. Because small to moderate changes in renal status can cause rapid increase in serum drug levels, the nurse must constantly monitor kidney function in patients receiving drugs that may be nephrotoxic or having low margin of safety. The pharmacotherapy of renal failure is...
Always present if we try to analyze it. Drugs that can easily be changed into a gaseous form are especially suited for excretion by the respiratory system. Now, the rate of respiratory excretion is dependent on factors that affect drug exchange, including diffusion. gas solubility, and pulmonary blood flow.
The elimination of vola greater the excretion. Conversely, the respiratory renal removal of water-soluble agents such as Alcohol is more dependent on blood flow to the lungs. The greater the blood flow into lung capillaries, the greater the excretion. In contrast, with other methods of excretion, the lungs excrete most drugs in their original non-metabolized form. Glandular activities, another elimination mechanism wherein water-soluble drugs may be excreted into the saliva, the sweat, or breast milk.
The odd taste that patients sometimes experience when given IV drugs is an example of the secretion of agents into the saliva. Another example of glandular excretion is the garlic smell that can be detected when standing next to a perspiring person who has recently eaten garlic. Excretion into breast milk is of considerable importance for basic drugs such as morphine or codeine because these can achieve high concentrations.
and potentially affect the nursing infant. Nursing mothers should always check with their health care provider before taking any prescription medication. Over-the-counter drug or herbal supplement could be considered also. Pharmacology of the pregnant or Breastfeeding patient is often a necessary part of excretion or drug excretion for they're able to detect and give information of the health of the infant. Some drugs, they are secreted in the bile.
a process known as biliary excretion. In many cases, drugs secreted into bile will enter the duodenum and eventually leave the body in the feces. However, most bile circulated back to the liver by enterohepatic recirculation will be a part of The excretion of the medication. A percentage of the drug may be recirculated numerous times with the bile. Biliary reabsorption is extremely influential in prolonging the activity of cardiac glycosides.
Now, some antibiotics and phenothiazines, recirculated drugs. are ultimately metabolized by the liver and excreted by the kidneys. Recirculation and elimination of drugs through biliary excretion may continue for several weeks after therapy has been discontinued. Remember the routes for your drug excretion.
You have the kidneys, main organ for drug elimination. they could pass the drugs to be eliminated into the primary area which is your urine. Free or unbound water soluble drugs, they are filtered inside the kidney and if your kidney has disease, the dosage of the medication must also be decreased in order to not torture the kidneys and further damage it. Again, your kidneys, they are the main route of drug excretion.
It could also be bile, lungs, saliva, sweat, and breast milk. Urine pH influences the drug excretion. Always remember, your normal urine pH, 4.6 to 8. Acidic urine will promote the elimination of weak-based drugs. Alkaline urine promotes elimination of weak acid drugs. Now you have your pre-renal, intra-renal, and post-renal conditions of patients who are excreting the drugs.
That will be the end of your pharmacokinetics. All of the information are based on your book, Pharmacology, A Patient-Centered Nursing Process Approach, 11th Edition, by McQuistion, Linda E., and the rest of those authors who contributed for the book. Thank you very much, everyone. Have a nice day.