Systemic Pharmacology - Midterm 1

Some drugs have the ability to deposit in certain tissues and build up over time. When this happens, the release of the drug into the bloodstream may be slower than usual. This drug deposition can also lead to changes in the tissues where the drug accumulates. Two examples of drugs known to have this issue are amiodarone/Pacerone and doxycycline/Vibramycin.

Albumin is a major serum carrier, many drugs target albumin to help get it to the site of action. If a pt has a low albumin level and they have to take drugs that need albumin as a carrier the patient is often given serum from blood fractions.

Protein bound drugs can reach higher concentrations between the blood and the tissues, whereas unbound, or free drug will reach an equilibrium between the blood and tissues.

Decreases serum free drug usually means that there is less available drug to concentrate in a target organ.

this is one of the quiz questions from class

This is an example of intended use of the drug effecting the formulation of the drug.

Molecules that are structurally similar can compete for carriers in drug transport mechanisms. Noncovalent binding allows drugs to bind to carriers, which then facilitate diffusion or carrier assisted diffusion. This means that drugs with similar structures can potentially interfere with each other's transport by competing for the same carriers. Therefore, the statement is true.

The phenomenon described in the question is typically called the "first pass effect." This refers to the metabolism or alteration of a drug that occurs in the liver after it is absorbed from the gastrointestinal tract. The drug is metabolized before it reaches systemic circulation, which can result in a significant reduction in its bioavailability. As a result, a higher oral dose of the medication may be required compared to a parenteral (non-oral) dose to achieve the desired therapeutic concentration in the bloodstream.

Pg. 9 - under clinical situation

Based on the given information, it sounds like the patient is experiencing an adverse drug effect (ADE). The patient's episodes of delirium and hallucinations could be side effects or negative reactions to the new heart medication prescribed by their cardiologist.

Substrates are drugs that are metabolized by CYP enzymes, meaning these enzymes break down the drugs into smaller molecules. Inducers, on the other hand, are drugs that stimulate the production of CYP enzymes in the body. So, substrates are the drugs that are metabolized by CYP enzymes, while inducers are the drugs that cause the production of CYP enzymes.

It can be mistaken for "SC" - subcutaneous

The correct answer is "Clindamycin 600 milligrams, one tablet orally every eight hours for a treatment course of seven days". This option accurately converts the shorthand prescription into lay person terms by specifying the dose (600 milligrams), route of administration (orally), frequency (every eight hours), and duration (seven days) of the medication.

An idiosyncrasy is a term used to describe an unusual or unexpected response to a drug. In this case, the patient experienced the unexpected side effect of eyelash loss after taking moxifloxacin for bacterial conjunctivitis. This idiosyncratic reaction is not a common or typical response to the drug, but rather a unique reaction specific to this individual.

pg. 10 - Oral one of the easiest routes for patients to dose themselves. Medications for oral administration should ideally be acid stable to withstand the low pH environment of the stomach. They should be absorbed quickly and passed through the intestinal lining in order to enter the bloodstream.

The correct answer is "Docusate sodium 100 milligrams, one tablet orally twice daily as needed for constipation." This option accurately translates the shorthand instructions to lay person terms, specifying the medication (Docusate sodium), the dosage (100 milligrams), the route of administration (orally), the frequency (twice daily), and the indication (as needed for constipation).

You know that because of the first pass effect you will be able to administer a lower dosage through an IV. Only one answer choice is lower than the dosage for the oral dosage of metoprolol

High affinity drug molecules are less likely to become dissociated from their binding sites than low affinity molecules. This means that high affinity molecules have a stronger attraction or binding to their target sites, resulting in a more stable interaction. As a result, it is less likely for these molecules to be displaced or dissociated from their binding sites compared to low affinity molecules.

Altered absorption - drugs may inhibit absorption of other drugs across physiologic membranes. Not all altered absorption is due to chelation

An anti-ulcer medication that coats the stomach may decrease the GI absorption of other drugs = example of physiologic barrier to altered absorption.

Metoprolol is for hypertension, and lopressor is the brand name
Moxifloxacin is for Tx of bacterial conjunctivitis
Vancomycin and gentamicin is required t treat bacterial endocarditis

Option 1: expects pt to know they need to take 2 25mg tablets
Option 2: lacks concentration and route
Option 3: correct
Option 4: gives amount for entire day, but it doesn't specify division of doses

Antagonism: Drug inhibits the effect of another drug. Usually the antagonist has no inherent activity. "1 + 1 = 0"

Synergism refers to the intended clinical effect(s), not potential adverse effects.

The last option refers to subcutaneous which is a form of Parenteral route of drug administration

SC and SQ can both be used to mean subcutaneous - SQ is more common in the medical setting

Option 3: NEVER abbreviate units as "U" because it can look like a "0" and they will give 50 units of insulin instead of 5

DC = discontinue
HS = at bedtime
AC = BEFORE meals
PC = AFTER meals

Additive effects - The response elicited by combined drugs is EQUAL to the combined responses of the individual drugs. 1 +1 = 2

Sedatives combined with opiates are a good example

Option 1: not as concise as Option 2
Option 3: which eye?
Option 4:no amount given

SCr more sensitive

Example question from class - she said most of her questions would be in this fashion.

The correct answer is "Levothyroxine 75mcg, one tab P.O. qAM one hr prior to breakfast". This answer accurately converts the original prescription to shorthand by using the appropriate abbreviation for micrograms (mcg) and indicating the route of administration (P.O. for orally). It also specifies the frequency (qAM for every morning) and timing (one hr prior to breakfast) for taking the medication. The other options either use the incorrect abbreviation for micrograms (mg) or do not provide the necessary instructions for timing and frequency.

Loading doses are given to reach therapeutic serum drug concentrations more quickly than administering routine intermittent doses. The first dose of the drug is calculated to be higher than the doses that will follow. This initial higher dose helps to rapidly achieve the desired drug levels in the body, allowing for a quicker onset of therapeutic effects. Once the loading dose has been administered, subsequent doses can be given at regular intervals to maintain the desired drug concentration in the body.

The response elicited by combined drugs is GREATER than the combined responses of the individual drugs. 1+1 = 3

Synergism refers to the intended clinical effect(s), not potential adverse effects.

A diabetic patient with impaired gastroparesis will have trouble with the oral route of drug administration because gastroparesis is a condition that affects the stomach's ability to empty its contents properly. This can result in delayed or inconsistent absorption of orally administered drugs, making it difficult for the patient to receive the intended therapeutic effects of the medication.

Opiate withdrawals can cause symptoms such as piloerection (goosebumps), diarrhea, insomnia, and irritability. However, seizures are not typically associated with opiate withdrawals.

The question asks for a factor that does not affect absorption through tissues and membranes. The options given are formulation, water solubility, molecular weight, ionization, and lipid solubility. All of these factors can affect absorption to some extent. Formulation refers to the composition and preparation of the drug, which can affect its absorption properties. Water solubility and lipid solubility determine how easily the drug can dissolve in water or lipids, respectively, which can affect its ability to cross membranes. Molecular weight and ionization can also impact the drug's ability to pass through tissues and membranes. Therefore, none of the above options are correct as they are all drug-based factors that can affect absorption.

The statement "Aspirin is an example of a chemical name that is irrespective of the manufacturer" is false. The chemical name of a drug is specific to its chemical structure and is not affected by the manufacturer. However, the trade name or brand name of a drug, such as Bayer Aspirin, can vary depending on the manufacturer.

Physiologic dependence - occurs when the body physically/ physiologically develops reliance on a drug. Abrupt drug discontinuance can lead to adverse effects including but not limited to withdrawal, rebound etc.

This is a danger in drugs such as Prednisone and opiate narcotics as well

The correct answer is 5. Each half-life of a drug eliminates 50% of the remaining dose. Therefore, after 1 half-life, 50mg of the drug would remain. After 2 half-lives, 25mg would remain. After 3 half-lives, 12.5mg would remain. After 4 half-lives, 6.25mg would remain. And after 5 half-lives, only 3.125mg would remain. Since 95% or more of the drug dose needs to be eliminated, it would take at least 5 half-lives to achieve this.

Option 2 - false statement, in class she said if you have trouble getting to the site of action because you have a low serum concentration then you would have a longer half life

Phase II reactions are when a polar molecular group is conjugated to the drug, which substantially increases its polarity

Phase I reactions: drugs are oxidized or reduced to a more polar form

NPO - means nothing by mouth

Rectal/PR is the route to use when all other other routes are unavailable, in this case it's the only one available

Example of question from class

This question is asking about the consideration that needs to be taken into account in drug formulation when drugs like insulin are denatured by acid and are not effective when administered orally due to the low pH environment of the stomach. The correct answer, "Drug stability in various physiologic environments," explains that the formulation of the drug needs to ensure its stability in different physiological environments, such as the stomach's low pH, in order for it to be effective when administered orally.

Material from pg. 29 and 30 of the manual

Don't confuse potentiation with synergism.
Potentiation: A drug which has no principal effect enhances the effect of a second drug. "0 + 1 = 2"

Remember: Amoxicillin with clavulanate is trademarked as AUGMENTin

Altered excretion - drugs may act on the kidneys to reduce or enhance excretion of specific drugs. Important because if you have damaged kidneys other routes must be explored.

One of her questions from class, I just changed the options a bit.

Passive diffusion does not require energy or a transport carrier . This transport mechanism would be slow for larger, ionic , hydrophilic molecules.

Hydrophilic channels best fit the description provided. These channels allow the passive diffusion of drugs with a molecular weight less than 200, without requiring energy or a transport carrier. Passive diffusion refers to the movement of molecules along a concentration gradient, without the need for any external energy source or carrier molecule. Hydrophilic channels provide a pathway for these drugs to move through the cell membrane, taking advantage of their small size and hydrophilic nature.

The statement that drug solubility and formulation does not limit the ability of drugs to be administered intravenously is not true. Drug solubility and formulation are important factors to consider when administering drugs intravenously. Some drugs may not be soluble in water or may have a formulation that is not suitable for intravenous administration. Therefore, drug solubility and formulation can indeed limit the ability of drugs to be administered intravenously.

Most drugs are absorbed in the duodenum and the jejunum, which are parts of the small intestine. These sections of the small intestine have a large surface area and are lined with specialized cells that facilitate the absorption of medications into the bloodstream. However, a few medications can also be absorbed in the stomach lining, although this is less common compared to absorption in the duodenum and jejunum. The stomach lining has a different structure and function compared to the small intestine, but it can still allow for some limited absorption of certain drugs.

The CrCL (Creatinine Clearance) is a measure of how well the kidneys are functioning. It is calculated using the serum creatinine level, age, weight, and gender of the individual. In this case, the given information includes the age, height, weight, and serum creatinine level of a 62-year-old female. By using these parameters, the calculated CrCL is 28.9 ml/min.