The participants were individually presented with two pharmacological clinically relevant written patient cases, which they were to analyze and propose a solution to. Participants were allowed to use the Swedish national drug formulary. Immediately thereafter the students were interviewed about their assessments. The interviews were audio-recorded and transcribed verbatim. A thematic analysis was used to identify units of meaning in each interview.
The chemical nature of a drug strongly influences ho ability to cross cell membranes. But not all drugs exert actions through direct binding to receptors. International Journal of Clinical Pharmacy. The cases were designed to imitate common health care provider-patient interactions. This process is known as facilitated diffusion. The removal of a drug from the plasma is known as Young bitch blow job and the distribution of the drug in the various body tissues is known as the volume of Importance of half life to nurses. ER formulations can be dosed less frequently and Ikportance improve patient compliance. Current Importance of half life to nurses comprehensive knowledge of the pharmacokinetics and pharmacodynamics of drugs have implications for nursing management Impportance patient care. In the brain, the capillary structure is continuous, and there are no slit junctions. This is the period of time required for the concentration or amount of drug in the body to be reduced by one-half.
Cumshots hardcore. JAN interactive
These teams could attempt to provide a secure environment for the patient where symptoms are expertly managed. EOL care helps to make death a coming-together. Email required Address never made public. Historically, EOL care was depicted as an important aspect of the life process, although it was not well advanced. The first line of therapy will involve neuroleptics. Great article packed with helpful advice. Acceptance haalf a good starting point for combating stress. How tto we give when we are running on empty? Everyone does this his or her Importance of half life to nurses way, but oftentimes concern about pain and symptom management interferes with this very involved and valuable process. Improvement in positive communication techniques with the patient and family is another area that needs to be addressed. Two major focus areas for improvement have been identified as spiritual- psychosocial health areas and physical health areas. Haloperidol and prochlorperazine act centrally Free teen webcam mpeg decrease nausea and are frequently lifr Tomko,
- Nurses have many jobs in a hospital, like giving people their medicine, taking blood samples, answering questions and checking to make sure that people in the hospital are okay.
- For example, the half-life of a radioactive substance is the amount of time it takes for half of its atoms to decay, and the half-life of a drug is the amount of time it takes before half of the active elements are either eliminated or broken down by the body.
- Without it, we risk long-term negative effects on our physical and mental health, our relationships, and our work performance.
- Every medication has a certain amount of time that it remains "active" before the body begins to metabolize or excrete the medication.
Toggle Navigation. The duration of action of a drug is known as its half life. This is the period of time required for the concentration or amount of drug in the body to be reduced by one-half. We usually consider the half life of a drug in relation to the amount of the drug in plasma. A drug's plasma half-life depends on how quickly the drug is eliminated from the plasma.
A drug molecule that leaves plasma may have any of several fates. It can be eliminated from the body, or it can be translocated to another body fluid compartment such as the intracellular fluid or it can be destroyed in the blood. The removal of a drug from the plasma is known as clearance and the distribution of the drug in the various body tissues is known as the volume of distribution. Both of these pharmacokinetic parameters are important in determining the half life of a drug. Document Top.
Get help. And why is it really important to understand the half-life of the drug you are tapering off of? Watch the Did-You-Know slideshow. Demonstrate skill at implementing a plan for improved end-of-life care within a dynamic and complex health care delivery system. They are measuring for its byproducts.
Importance of half life to nurses. JAN interactive
Pharmacokinetics refers to what the body does to a drug, whereas pharmacodynamics describes what the drug does to the body. Four pharmacokinetic properties determine the onset, intensity, and the duration of drug action. Using knowledge of pharmacokinetic parameters, clinicians can design optimal drug regimens, including the route of administration, the dose, the frequency, and the duration of treatment. The route of administration is determined by the properties of the drug for example, water or lipid solubility, ionization and by the therapeutic objectives for example, the desirability of a rapid onset, the need for long-term treatment, or restriction of delivery to a local site.
Major routes of drug administration include enteral, parenteral, and topical, among others. The drug may be swallowed, allowing oral delivery, or it may be placed under the tongue sublingual , or between the gums and cheek buccal , facilitating direct absorption into the bloodstream. A wide range of oral preparations is available including enteric-coated and extended-release preparations. The buccal route between the cheek and gum is similar to the sublingual route.
The parenteral route introduces drugs directly into the systemic circulation. Parenteral administration is used for drugs that are poorly absorbed from the GI tract for example, heparin or unstable in the GI tract for example, insulin. Parenteral administration is also used if a patient is unable to take oral medications unconscious patients and in circumstances that require a rapid onset of action.
In addition, parenteral routes have the highest bioavailability and are not subject to first-pass metabolism or the harsh GI environment. However, these routes of administration are irreversible and may cause pain, fear, local tissue damage, and infections. The three major parenteral routes are intravascular intravenous or intra-arterial , intramuscular, and subcutaneous. Absorption is the transfer of a drug from the site of administration to the bloodstream. The rate and extent of absorption depend on the environment where the drug is absorbed, chemical characteristics of the drug, and the route of administration which influences bioavailability.
Routes of administration other than intravenous may result in partial absorption and lower bioavailability. Depending on their chemical properties, drugs may be absorbed from the GI tract by passive diffusion, facilitated diffusion, active transport, or endocytosis. However, the protonated form of basic drugs is usually charged, and loss of a proton produces the uncharged base B :. Therefore, the effective concentration of the permeable form of each drug at its absorption site is determined by the relative concentrations of the charged and uncharged forms.
The ratio between the two forms is, in turn, determined by the pH at the site of absorption and by the strength of the weak acid or base, which is represented by the ionization constant, pKa. Bioavailability is the rate and extent to which an administered drug reaches the systemic circulation. For example, if mg of a drug is administered orally and 70 mg is absorbed unchanged, the bioavailability is 0.
Determining bioavailability is important for calculating drug dosages for nonintravenous routes of administration. Determination of bioavailability: Bioavailability is determined by comparing plasma levels of a drug after a particular route of administration for example, oral administration with levels achieved by IV administration. When the drug is given orally, only part of the administered dose appears in the plasma. By plotting plasma concentrations of the drug versus time, the area under the curve AUC can be measured.
The total AUC reflects the extent of absorption of the drug. This biotransformation, in addition to the chemical and physical characteristics of the drug, determines the rate and extent to which the agent reaches the systemic circulation.
Two drug formulations are bioequivalent if they show comparable bioavailability and similar times to achieve peak blood concentrations. Two drug formulations are therapeutically equivalent if they are pharmaceutically equivalent that is, they have the same dosage form, contain the same active ingredient, and use the same route of administration with similar clinical and safety profiles. Therefore, two drugs that are bioequivalent may not be therapeutically equivalent.
Drug distribution is the process by which a drug reversibly leaves the bloodstream and enters the interstitium extracellular fluid and the tissues. For drugs administered IV, absorption is not a factor, and the initial phase from immediately after administration through the rapid fall in concentration represents the distribution phase, during which the drug rapidly leaves the circulation and enters the tissues. The distribution of a drug from the plasma to the interstitium depends on cardiac output and local blood flow, capillary permeability, the tissue volume, the degree of binding of the drug to plasma and tissue proteins, and the relative lipophilicity of the drug.
The rate of blood flow to the tissue capillaries varies widely. Adipose tissue, skin, and viscera have still lower rates of blood flow. Variation in blood flow partly explains the short duration of hypnosis produced by an IV bolus of propofol. High blood flow, together with high lipophilicity of propofol , permits rapid distribution into the CNS and produces anesthesia.
A subsequent slower distribution to skeletal muscle and adipose tissue lowers the plasma concentration so that the drug diffuses out of the CNS, down the concentration gradient, and consciousness is regained. Capillary permeability is determined by capillary structure and by the chemical nature of the drug.
Capillary structure varies in terms of the fraction of the basement membrane exposed by slit junctions between endothelial cells. In the liver and spleen, a significant portion of the basement membrane is exposed due to large, discontinuous capillaries through which large plasma proteins can pass.
In the brain, the capillary structure is continuous, and there are no slit junctions. To enter the brain, drugs must pass through the endothelial cells of the CNS capillaries or be actively transported. For example, a specific transporter carries levodopa into the brain. By contrast, lipid-soluble drugs readily penetrate the CNS because they dissolve in the endothelial cell membrane. Ionized or polar drugs generally fail to enter the CNS because they cannot pass through the endothelial cells that have no slit junctions.
These closely juxtaposed cells form tight junctions that constitute the blood—brain barrier. The chemical nature of a drug strongly influences its ability to cross cell membranes. These drugs dissolve in the lipid membranes and penetrate the entire cell surface. The major factor influencing the distribution of lipophilic drugs is blood flow to the area. In contrast, hydrophilic drugs do not readily penetrate cell membranes and must pass through slit junctions.
The apparent volume of distribution, Vd, is defined as the fluid volume that is required to contain the entire drug in the body at the same concentration measured in the plasma. It is calculated by dividing the dose that ultimately gets into the systemic circulation by the plasma concentration at time zero C0.
Although Vd has no physiologic or physical basis, it can be useful to compare the distribution of a drug with the volumes of the water compartments in the body. Distribution into the water compartments in the body: Once a drug enters the body, it has the potential to distribute into any one of the three functionally distinct compartments of body water or to become sequestered in a cellular site.
Apparent volume of distribution: A drug rarely associates exclusively with only one of the water compartments of the body.
Instead, the vast majority of drugs distribute into several compartments, often avidly binding cellular components, such as lipids abundant in adipocytes and cell membranes , proteins abundant in plasma and cells , and nucleic acids abundant in cell nuclei. Therefore, the volume into which drugs distribute is called the apparent volume of distribution Vd.
Vd is a useful pharmacokinetic parameter for calculating the loading dose of a drug. Determination of Vd: The fact that drug clearance is usually a first-order process allows calculation of Vd. First order means that a constant fraction of the drug is eliminated per unit of time. The concentration of drug in the plasma can be extrapolated back to time zero the time of IV bolus on the Y axis to determine C0, which is the concentration of drug that would have been achieved if the distribution phase had occurred instantly.
Effect of Vd on drug half-life: Vd has an important influence on the half-life of a drug, because drug elimination depends on the amount of drug delivered to the liver or kidney or other organs where metabolism occurs per unit of time. Delivery of drug to the organs of elimination depends not only on blood flow but also on the fraction of the drug in the plasma. Therefore, any factor that increases Vd can increase the half-life and extend the duration of action of the drug.
Your email address will not be published. This site uses Akismet to reduce spam. Learn how your comment data is processed. Remember me. Lost your password? Absorption: First, absorption from the site of administration permits entry of the drug either directly or indirectly into plasma.
Distribution: Second, the drug may then reversibly leave the bloodstream and distribute into the interstitial and intracellular fluids. Metabolism: Third, the drug may be biotransformed by metabolism by the liver or other tissues.
Elimination: Finally, the drug and its metabolites are eliminated from the body in urine, bile, or feces. Enteric-coated preparations: An enteric coating is a chemical envelope that protects the drug from stomach acid, delivering it instead to the less acidic intestine, where the coating dissolves and releases the drug. Enteric coating is useful for certain drugs for example, omeprazole that are acid unstable. Drugs that are irritating to the stomach, such as aspirin, can be formulated with an enteric coating that only dissolves in the small intestine, thereby protecting the stomach.
Extended-release preparations: Extended-release abbreviated ER or XR medications have special coatings or ingredients that control the drug release, thereby allowing for slower absorption and a prolonged duration of action. ER formulations can be dosed less frequently and may improve patient compliance.
Additionally, ER formulations may maintain concentration within the therapeutic range over a longer period of time,as opposed to immediate-release dosage forms, which may result in larger peaks and troughs in plasma concentration. For example, the half-life of oral morphine is 2 to 4 hours, and it must be administered six times daily to provide continuous pain relief. However, only two doses are needed when extended release tablets are used.
Parenteral Focus topic: Pharmacokinetics The parenteral route introduces drugs directly into the systemic circulation.
It is useful for drugs that are not absorbed orally, such as the neuromuscular blocker rocuronium. IV delivery permits a rapid effect and a maximum degree of control over the amount of drug delivered. If administered as an IV infusion, the drug is infused over a longer period of time, resulting in lower peak plasma concentrations and an increased duration of circulating drug levels.
Unlike drugs given orally, those that are injected cannot be recalled by strategies such as binding to activated charcoal. IV injection may inadvertently introduce infections through contamination at the site of injection. It may also precipitate blood constituents, induce hemolysis, or cause other adverse reactions if the medication is delivered too rapidly and high concentrations are reached too quickly. Therefore, patients must be carefully monitored for drug reactions, and the rate of infusion must be carefully controlled.
Intramuscular IM : Drugs administered IM can be in aqueous solutions, which are absorbed rapidly, or in specialized depot preparations, which are absorbed slowly. Depot preparations often consist of a suspension of the drug in a nonaqueous vehicle such as polyethylene glycol. As the vehicle diffuses out of the muscle, the drug precipitates at the site of injection.
The drug then dissolves slowly, providing a sustained dose over an extended period of time. SC injection minimizes the risks of hemolysis or thrombosis associated with IV injection and may provide constant, slow, and sustained effects. This route should not be used with drugs that cause tissue irritation, because severe pain and necrosis may occur.
Drugs commonly administered via the subcutaneous route include insulin and heparin.