Pharmacology

Information is from his notes. Good luck!

Pharmacokinetics

The movement of drugs

4 phases of pharmokinetics

Absorption

Distribution

Metabolism

Excretion

Absorption

The movement into the blood stream

Distribution

Movement from the blood into the tissue and cells

Metabolism

Change in drug shape/structure

Excretion

Movement out of the body

Enteral and Parenteral

What are the two major absorption routes?

Enteral

Through the GI tract

Parenteral

Through injections

Topical medications

Administered directly to the treatment site

Examples of topical medications

Skin ointments, eye drops, ear drops, vaginal medications

Transdermal medications

Are applied to the skin but absorbed systemically

Examples of transdermal medications

Nicotine patches, nitroglycerin patches, birth control patches, testosterone

Inhaled medication

Meant to exert local effects (asthma medication) but may also be used for systemic effects (oxygen and anesthesia)

Why do medications have trouble passing the blood-brain barrier?

The capillaries do not have pores to allow nutrients and medications to enter and exit the circulatory system. Because of the blood brain barrier

Lipid-Soluble Medications

Can pass through cell membranes

Water-Soluble Medications

Do not pass through cell membranes and require alternative processs for cell membrane diffusion

How are water-soluble medications normally administered?

Intravenously

What is the absorption rate of IV medications?

100%, takes 20 seconds to medication to reach the brain (why we “push” medications slowly)

How do you treat an abscess?

You have to make an incision to drain it

What prevents medication from entering abscesses?

Their thick outer barrier

Half-Life

The amount of time it takes to metabolize half of a drug

After how many half-lives do we consider a drug to be gone?

4

Never crush or dissolve what kind of medications?

Extended release, long-acting, or continuous-release medications

Where are drugs metabolized?

In the liver

Cytochrome P450 System

A group of enzymes responsible for most of all drug metabolism.

Polypharmacy

Taking multiple medications, common in the elderly

Why are herbal medications not safe?

They are less regulated, can contain multiple active ingredients and may vary in concentration from pill to pill

Homeopathic medications

Essentially water, considered to be stronger the more you dilute them

Grapefruit juice is a strong inhibitor of what?

CYP3A4

What organ is responsible to the excretion of medication?

The kidneys

Two tests kidney function

Creatinine and BUN

Receptors

The “switches” that drugs either turn on or off

Agonists

Activate receptors

Antagonists

Block or inhibit receptors, called drug blockers

Partial Agonists

Partially activate receptors

An example of a receptorless drug

Tums or antibiotics

Generic names

Are always written in lowercase unless they are at the start of a sentence

Trade names

Are always capitalized

What is the difference between brand name and generic name medications?

The inactive ingredients, they may dissolve or absorb at different rates.

Adverse Effects

Any extra effect that you do not wish to happen.

Side Effects

Milder than adverse effects and are somewhat expected.

Black Box Warning

Severe adverse effects that the FDA wants to being to the prescriber’s attention.

Contraindications

Drugs that should be avoided if the client has a certain condition.

Precautions

Warn you that a client is at a higher risk of experiencing adverse effects.

Toxicity

An adverse effect that can be life-threatening if drug levels are too high.

Therapeutic Index

In order for medications to work you need to have a sufficent amount of it in your blood.

How can you tell the medication level of your patient?

Run a blood test

CNS Depressant Drugs

Cause your brain to slow down, mellow out, become sleepy.

Strong doses can cause people to stop breathing.

What should be avoided when taking CNS depressing drugs?

Alcohol

CNS depressing drugs increase the patient’s risk of what?

Falls

Its best to take CNS depressing medications at what time?

Bedtime

CNS Excitation Drugs

These can cause irritability, anxiety, insomnia, and can even make you extremely talkative (loquaciousness).

Strong doses may make the patient have a seizure.

Its best to take CNS excitation drugs at what time?

In the morning

Extrapyramidal Symptoms

Produced by drugs that interfere with the extrapyramidal motor system.

Causes involuntary muscle movements or spasms.

Akthisia

Constant squirming, an inability to sit or stand still, severe restlessness.

The most common EPS

Parkinsonism

Slow movements, loss of facial expression, drooling, rigidity, tremors, stopped posture, and shuffling gait.

Tardive Dyskinesia

Usually occurs late in treatment (greater than 6 months)

May include abnormal movements of the mouth (smacking of the lips, lateral movement of the jaw), tongue, facial grimacing, and twisting movements (choreoathetosis) of the extremities and trunk.

Once developed, usually permanent

Parasympathetic Nervous System regulates what?

The “rest and digest” mode

Anticholinergic medications interfere with which bodily system?

Parasympathetic

Make it hard for your body to enter the “rest and digest” mode

Side effects of anticholinergic medications

Can’t see (dry eyes, pupil dilation (mydriasis)

Can’t spit (dry mouth xerostomia)

Can’t pee

Can’t shit

How can you counteract the side effects of anticholinergic medications?

Eyedrops and sunglasses help with the vision problems.

Frequent sips of water and sugarless candy can help with dry mouth.

Urine retention can be alleviated by voiding before taking the medication.

Drinking more water, walking, and increasing fiber intake can help with constipation.

Orthostatic Hypotension

When you from a horizontal position to a vertical position too quickly and the blood pools at your feet, causing you to feel lightheaded.

Prolonged QT Intervals can lead to what?

Torsade’s de pointes

Torsade’s de pointes can lead to what?

Ventricular fibrillation

Neutropenia

Loss of white blood cells

Thromnocytopenia

A loss of platelets

Hemolytic Anemia

Premature loss/destruction of red blood cells

What are the two lab tests that we use to identify liver failure?

AST and ALT

Signs and symptoms of Liver Faliure

Jaundice

Anorexia

Upper abdominal pain

Nausea, vomiting and diarrhea

Dark urine

Increased need for sleep

Clay colored stools

Ecchymosis, encephalopathy

What tests do we run to check a patient’s kidney function when they are taking a medication that can cause nephrotoxicity?

Serum creatinine

BUN levels

Mild allergic reactions

A rash or hives

Mostly treated with diphenhydramine and patient is told not to take that medication any longer

Anaphylactic Reactions

A life-threatening reaction

Causes the client’s airway to close and severe hypotension.

Stop the medication, give epinephrine, help maintain the airway, and monitor the client closely.

What medication class is most likely to cause anaphylactic reactions?

Penicillin’s

What three groups are most at risk for developing an adverse to a medication?

Children, elderly, and pregnant women

Pediatric Considerations

The blood brain barrier is not fully developed at birth. So infants are more sensitive to drugs that affect the central nervous system.

The liver and kidney are not fully matured until about age 1.

Elderly Considerations

Many older adults take many medications (polypharmacy) meaning they are more likely to have drug interactions that can cause levels to be too high or too low.

Their liver and kidney function are decreased.

They often have reduced serum albumin levels, this can alter drug distribution.

Pregnant Women Considerations

They experience a lot of nausea and vomiting, oral medications sometimes cannot be absorbed because of this.

Their liver and kidney function actually increase, meaning sometimes their dose needs to be increased.

Teratogens which can cause birth defects or fetal death.

They CANNOT receive live vaccines.

Its best to keep medications to a bare minimum during breastfeeding, if they need to take the medication they should take it AFTER breastfeeding.

Teratogens

Medications that are harmful to the fetus and are contraindicated when pregnant.

Cerebral Cortex

The “bark” of the brain.

Responsible for our human intellect.

The Cerebral Cortex is divided into 4 lobes:

Frontal, Temporal, Parietal, and Occipital

Frontal Lobe

Responsible for executive function.

Plays an important role in several mental disorders like ADHD and substance abuse.

Limbic System

Controls learning, memory, emotions (fear, anger, pleasure), and basic drives (hunger and sex)

Action Potential

An electrical charge that is fired down the axon.

Synapse

The minuscule gap in between neurotransmitters.

Dopamine

Used in the areas of the brain that regulate attention, concentration, pleasure, energy, motivation, mood, and muscle movements.

Norepinephrine

Used in the areas of the brain that regulate mood, alertness, concentration, and energy.

Also activates the “fight and flight” response, excessive amounts can lead to anxiety and agitation

Serotonin

90% of it is found in the lining of your intestines. Raphe nuclei produces a very small amount in the brain.

Helps regulate mood, anxiety, sexual desire, and appetite.

Glutamate

The main excitatory neurotransmitter.

It acts like the brains gas pedal.

Gamma-Aminobutyric Acid (GABA)

Main inhibitor neurotransmitter.

Acts like the brake pedal.

Can reduce anxiety, help indue sleep, and stop or prevent seizures.

Acetylcholine

Used in brain areas that regulate attention and memory.

It’s helpful to increase acetylcholine levels if a client has Alzheimer’s.

Diffusion

Once neurotransmitters enter the synapse, they will eventually float away into the surrounding cerebrospinal fluid, where they can no longer activate postsynaptic receptors.

Enzymatic Degradation

The brain makes enzymes that break apart neurotransmitters.

Reuptake

The presynaptic terminal has pumps that can suck neurotransmitters back inside the presynaptic terminal where they can be recycled for future use.

Monoamine Oxidase Inhibitors

Phenelzine

MAOIs Mechanism of Action

Work by blocking monoamine oxidase, which is the enzyme that breaks down dopamine, norepinephrine, and serotonin.

Increases serotonin, dopamine, and norepinephrine levels in the synapses, elevating the client’s mood and energizing them.

MAOIs Food Interactions

Clients must avoid foods containing tyramine.

Avoid foods that are old and stinky like:

Most cheeses

Aged processed meats (bologna, salami, pepperoni, liver)

Smoked or pickled fish

Overly ripened fruit (figs, avocados, old bananas)

Sauerkraut

Soy sauce

MAOIs Drug Interactions

Clients should avoid drugs that increase serotonin, dopamine, and norepinephrine like:

Other antidepressants

Over the counter cold medications. (pseudoephedrine or phenylephrine, common nasal decongestants)

Meperidine (a strong pain medication)

Triptans (a class of migraine medications)

MAOIs Hypertensive Crisis

Excessive amounts of tyramine will cause a client’s blood pressure to skyrocket. The same thing would happen if a client’s norepinephrine levels became too high.

Severe hypertension can manifest as a headache.

Can also cause orthostatic hypotension.

MAOIs Serotonin Syndrome

Serotonin syndrome is characterized by an altered mental status, high fever, sweating, and clonus.

Clonus us an involuntary rhythmic muscle contraction and is the most reliable indicator of serotonin syndrome.