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Basic Pharmacokinetic Concepts(Dari)

EO 003.01 Part 15

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Importance of Lesson(Dari)

Pharmacy technicians are required to have a basic understanding of what the body does to drugs in order to understand the factors that affect the dosing of medications.

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Overview of Lesson(Dari)

• Definitions• Absorption • Distribution • Metabolism • Excretion• Factors that influence drug dosage

and action• In-class Assignment

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Definitions (Insert Dari)

Pharmacokinetics – what the body does to the drug. Includes the following four stages:

(1) Absorption of drug(2) Distribution of the drug (3) Metabolism of the drug(4) Excretion of the drug

Pharmacodynamics – what the drug does to the body (will be covered in future lectures).

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Routes of Administration(Insert Dari)

This will be covered in more detail during EO 003.02Insert Dari

Topical (Insert Dari)

Oral (Insert Dari)

Intravenous (Insert Dari)

Transdermal (Insert Dari)

Subcutaneous (Insert Dari)

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Absorption (Insert Dari)

The process by which the drug enters the body through the bloodstream. Some substances work outside the body but most must enter the body in order to work.

Most drugs will undergo intestinal absorption through the GI tract.

Drugs that are administered intravenously are an exception as they are directly administered to the bloodstream and do not undergo absorption.

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Absorption: Oral vs Intravenous Administration

Route Benefits DisadvantagesOral • Safe

• Convenient• No need for sterile equipment

• Variable absorption – only a percentage of the drug ingested is absorbed• Gastric irritation may cause vomiting (not useful if patient is vomiting) • Requires cooperation of patient• Onset of effect is slow

Intravenous • Extremely rapid effect• Initial absorption step is by-passed (immediately enters the bloodstream) • Drug levels are more accurately controlled

• Most dangerous route• Drug must be in aqueous solution • Must be performed slowly • Once injected, drug cannot be removed

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Distribution(Insert Dari)

The movement of the drug from the blood to the body tissue.

Factors that effect drug movement in body tissues include blood flow to the tissue (i.e. organs = fast, muscle = slow) as well as characteristics of the drug.

Some characteristics include: - Size of the drug- Water solubility - Lipid solubility

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Water-soluable vs Lipid soluable Medications(Insert Dari)

Lipid soluble – the drug mixes well with fats.

If a drug is lipid soluble that means that it can easily pass through the outer membrane of a cell (which is composed of lipids).

It also means that the drug will distribute well into the fat tissue = accumulation of drug in the body.

Water soluble – the drug mixes well with water and as a general rule does not mix well with fats.

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Metabolism (Insert Dari)

Metabolism- the modification of the chemical structure of a drug by the body. There are MANY steps to this process.

Metabolite – drug product that results from metabolism, may be more active or less active than the original/parent drug.

The majority of drug metabolism occurs in the liver.

There are variations among individuals as to how they metabolize medications and how quickly they do so.

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Elimination (Insert Dari)

Removal of the drug from the body.

Main route for this to occur is through the kidneys and excretion in the urine.

Some drugs may be reabsorbed via the kidneys and will require multiple metabolism steps before they can be excreted from the body.

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Dosing of medications(Insert Dari)

Dose = the amount of medication being administered.

Effective dose = dose of medication required to achieve the desired therapeutic effect.

Lethal dose = dose of medication that will cause death.

If a effective dose and lethal dose do not have much difference between them that drug has a narrow therapeutic range.

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Factors Influencing Drug Dosageمتاثرمیسازد را شده توصیه ادویه مقدار فکتورهایکه

• Age• Weight• Gender• Physical Health

سن•وزن•جنس•فزیکی • صحت

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Ageسن

• Infants:– Immature body systems– Not fully developed kidney and

liver functions• Children:

– Different physiologic profile and body mass distribution

– Dose per kilogram• Older adults:

– Depressed liver and kidney systems.

– Higher ratio of fat tissue to muscle tissue

– Increased risk for drug interactions

: خوار شیرنابالغ- طفل

ممکن- بشکل کبد و کلیوی سیستماست ننموده انکشاف

اطفال:یک- دارای و مختلف فزیکی نگاه از

خوبتر حجم با و برجسته شکلمیباشد

کیلوگرام- بر ادویه دوز: سال بزرک جوان

کلیوی- سیستم و کبد افسردگیانساج- مقدار تناسب افزائش

عضلی انساج به شهمیادویه- مداخله خطر افزائش

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Weight•وزن Children:

– Body surface area, height and weight are important factors in determining drug dosages

– Calculated by milligrams of drug per kilogram of body weight

• Adults:– Overweight and underweight adults– Average adult dose is based on a drug

quantity that will produce a particular effect in 50% of the population between 18 and 65 years of age and approximately 150 pounds in weight.

– Dosage may need to be adjusted for those who are extremely underweight or overweight.

اطفال: و- طول وجود، سطحی قسمت

در مهم های فکتور جمله از وزنمیباشد ادویه تعین

گیلوگرام - بر ادویه گرام ملیمیگردد محاسبه مریض وزن

: کاهالن کم- یا زیاد وزن با کاهالن

کاهالن- سنین در ادویه دوزادویه مقدار براساس متوسط

که خاص 50بوده تاثیرات فی̂صدرا

سنین تولید 65الی 18دربینوزن دارای تقریفاً و کرد خواهد

150. باشد پاندInsert Dari

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Genderارثیت

• Women higher percentage of body fat• Men higher percentage of body fluid• Drugs fat soluble, thus women may accumulate

more of these drugs in their body

Pregnancy • Drugs pass through the placenta and breast milk. • Very important to confirm if a patient is pregnant

and to make sure drugs are dosed properly to prevent harm to the developing baby or newborn.

بیشتر ها زن نزد در شهم فیصدیمیباشد

مرد نزد در وجود مایعات فیصدیاست بیشتر ها

معنی بدین شهم در منحل ادویهبیشتراین مقدار ها زن که است

دارند وجود در را ادویه

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مینماید انتقالInsert Dari

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Physical healthفزیکی صحت

Disease processes alter dosage requirements, particularly in clients with kidney, liver, digestive and cardiovascular problems.

که بوده مرض پروسه ازیک عبارتتوصیه ادویه مقدار های نیازمندی

مریضانیکه در مخصوصاً را شدهمشکالت

سیستم و وعائی قلبی کبد، کلیه،تغیرمیدهد، باشند داشته هضمی

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Questions? (Insert Dari)

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In-Class Assignment(Insert Dari)

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1. Put the following pharmacokinetic steps in the order in which they generally occur:

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A) Metabolism B) EliminationC) DistributionD) Absorption

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1. Put the following pharmacokinetic steps in the order in which they generally occur:

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D) AbsorptionC) DistributionA) Metabolism B) Elimination

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2. Answer: Which of the following is NOT true regarding intravenous and oral administration?

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A) Intravenous administration achieves a faster onset of action when compared to oral.

B) If a person is vomiting oral administration of medication is preferred.

C) Oral administration is convenient for the patient.

D) Intravenous administration skips the absorption step as the drug is administered directly into the blood stream.

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3. Fill in the blanks: The majority of drug metabolism occurs in the ______ and the majority of drugs are

eliminated via the _______.

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3. Answer: Fill in the blanks: The majority of drug metabolism occurs in the liver and the majority of drugs

are eliminated via the kidneys.

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4. Which of the following is best defined as the dose which achieves a desired therapeutic effect?

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A) Minimal doseB) Maximal doseC) Lethal doseD) Effective dose

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4. Which of the following is best defined as the dose which achieves a desired therapeutic effect?

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A) Minimal doseB) Maximal doseC) Lethal doseD) Effective dose

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5. Which of the following influences the dosing of a drug? (Insert Dari)

A) Gender B) WeightC) AgeD) All of the above

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5. Answer: Which of the following influences the dosing of a drug?

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A) Gender B) WeightC) AgeD) All of the above

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