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“Pharmacology Review”

Lets start with the definition of Pharmacology: Pharmacology is the study of the mechanism of action, uses, side effects and fate of drugs in the body.

Pharmacodynamics is how the biologically active compounds do in the body.

Pharmacokinetics is  how the body reacts the drugs.

Most of the drugs are synthetic in origin which means that they are made and discovered in the laboratory.  Although others can still be obtained from natural sources.  Any drug can have a chemical name, a generic name and a brand or trade name.

Usually, the generic name of a drug is suggested by the manufacturer, and accepted by the international committee.

Drugs, hormones and neurotransmitters that activate receptors are called agonists.

How the drug is being affected affects the body and the patient’s response is called the effect.

Efficacy refers to the degree to which a drug is able to induce it’s maximal effects.

Adverse Effect is any unexpected or unintended response to a therapeutic use of a drug, it is also called side effect.

First I want to talk about drugs that are used to treat infections:

ANTIBIOTICS

- basically an antibiotic is a drug that us used to treat infectious diseases.

B Lactam Antibiotics-  are antibiotics that have a B-Lactam ring in their molecule.  Example of B Lactam Antibiotics would include Penicillins and Cephalosporins.

I just want to go over the two basic types of Penicillin Antibiotics:

  1. Natural Penicillin (penicillin G pottasium)- used to treat moderate to severe infections.
  2. Broad Spectrum penicillin (amoxicillin)- also used to treat mild and moderate infections.

Contraindications: penicillins are contraindicated for patients with a history of allergic reaction to any penicillin or cephalosporins (this is always very important to know).

Adverse Reaction: Like I have mentioned before, penicillins are one of the most common cause of drug allergy.  Hypersensitivities to penicillins may appear in the form of rash, pruritis, fever, wheezing, severe dyspnea, nausea and vomiting.  It is also important to note that adverse effects of penicillins generally involves the gastrointestinal (GI) system with glostitis, mouths sores (stomatitis, abdominal bleeding.

Toxicity: Toxicity for penicillin involves  the neurologic, nephrologic,  and hematologic system.

Penicillins, when given with anticoagulants, increases bleeding time.

Nursing Interventions to take note when giving Penicillins:

  • It is very important to be aware of any allergies to penicillins
  • Take the drugs on an empty stomach with water.
  • Do not take with fruit juices or soft drinks.
  • Make sure to give patient an adequate hydration.

Aminoglycosides

  • gentamycin sulfate (garamycin)
  • kanamycin sulfate (kantrex)

Aminoglycosides are batericidal, they both bind irreversibly to both the 30 S and 50S ribosomes to prevent bacterial protein synthesism.  Aminnoglycosides are used to treat serious nosocomial infections (ie. gram negative bacteria, peritonitis, pneumonia).

- Aminoglycosides should be administered with caution in neonates because of their immature renal systems.

Nursing Responsibilies

  • Administer an aminoglycoside and penicillin at least 2 hours apart
  • draw peak and trough levels periodically throughout the therapy.
  • encourage patient to take the full course of treatment.

Tetracycline

- is used as a treatment of gram positive and gram negative infections.

- Remember: That a use of tetracycline with oral contraceptives leads to breakthrough bleeding, altered GI bacterial flora, decreased contraceptive effectiveness and an increased risk of pregnancy.

Now, I want to talk about drugs that are used to treat Nervous System Disorders:

The Sypathetic Nervous System: Hormones (norepinephrine and epinephrine) activate the sympathetic nervous system.  The sympathetic nerces release both of these hormones whereas tha drenal gland also releases epinephrine.    There are four types of receptor that is found in the autonomic nerve pathways:

  1. Alpha 1 Adrenergic
  2. Alpha 2 Adrenergic
  3. Beta 1 Adrenergic
  4. Beta 2 Adrenergic

You have to understand that several physiologic responses results when each type of receptor is activated.

Alpha 1 receptors affects:

  • pupil dilation
  • gastrointestinal tract motility
  • vasoconstriction of arterioles
  • bladder contraction, prostate contraction

Alpha 2 affects:

  • gastrointestinal motility
  • vasoconstriction of arterioles

Beta 2  receptors affects:

  • Heart rate
  • contractility, automaticity and conduction

Beta 2 receptors affects:

    • bronchodilation (breathing)
    • heart rate contractility
    • uterus (relaxation)

Adrenergic Agonists (Adrenergics or sympathomimetic agents)

  • Adrenergic Agonists can stimulate any one or any combination of Alpha or beta receptors.  Adrenergic agonsits that stimulate beta receptors are called Beta adrenergic agonists.
  • Example of adrenergic agonists drugs includes: phenylephrine (neo-synephrine): used to treat shocj and nasal congestion
  • Ephidrine (ephedsol) temporary relief for nasal and sinus congestion
  • Albuterol (Proventil) bronchospasm associated with asthma or bronchitis.

So, basically we can say that Adrenergic agonsists are used primarily for three reasons: hemodynamic compromise such as (hypotension resulting from shock or CHF, bronchospasm and nasal or sinus congestion)

  • Contraindications includes: For Phenylephrine, it is contraindicated in patients with pheochromocytoma.  Alpha agonists are contraindicated in patients who have tachycardia and severe hypertension because stimulation of the alpha receptor can further cause vasoconstriction and cause more potentiating hypertension.  Because alpha-agonists causes pupil dilation (mydriasis), they are contraindicated in patients with glaucoma.

Remember: Adrenergic agonists should be avoided in patients with cardiac diseases beacause these agents may precipitate angina or myocardial infarction (MI).

Adrenergic Antagonists

Adrenergic Antagonists: inhibits or blocks the effects of the sympathetic nervous system neurotransmitters and are antagonists to the adrenergic agonists.  Adrenegic antagonists are also sometimes calle antagonist blockers because they block the sympathetic effects of the body.

  • The action of the alpha adrenergic antagonists inclcudes:
  • pupil constriction (miosis), increase GI tract motility, vasodilation of arterioles which can result in a decrease in Blood pressure, and prostate relaxation.
  • Alpha adrenergic antagonists are used primarily to treat five conditions:  hypertension, migraine headaches, alzheimer’s disease and benign prostatic hyperthrophy
  • Examples of these drugs includes: doxazosin mesylate (Cardura) which is used for treatment of hypertension.

When administering  alpha adrenergic antagonist medications, always try to: monitor for orthostatic hypotension, monitor for tachycardia, and tell patient to report any gain of 1 to 2 pounds accompanied with peripheral edema.

Parasympathetic Nervous System Drugs

The parasympathetic Nervous System drugs is primarily concerned with conserving energy and promoting digestion.  Several responses of stimulation of the parasympathetic drugs includes: pupil constriction, lacrimation, salivation, bronchoconstriction, a decrease in heart rate, conduction, automaticity and contraction of the bladder and relaxation of the sphincter.  The parasympathetic nervous system drugs includes:

  1. Direct acting cholinergic agonists
  2. cholinesterase inhibitors
  3. anticholinergics
  4. Dopaminergics

Knowing your pharmacology is essential for the nclex.  The proper way to study pharmacology and the drugs for the nclex exam is to understand the interaction of the drug with our body.  Memorizing the purpose and side effects of this drugs without understanding fully the rationale of its actions will set you to fail the nclex exam.  Therefore, to prepare for the nclex, a firm understanding and knowledge of pharmacology is essential, and yes there will be a lot of “drug” related questions in the nclex exam.  In this nclex review, we will start with the Central Nervous System:

Local Anaesthetics includes Lidocaine (xylocaine). It is an anesthetic that blocks nerve conduction; metabolized by hepatic enzymes.

Non- narcotic analgesics and antipyretic: This group would include your aspirins, and your antipyretic.  Acetysaalicylic Acid (aspirin) (ASA):  Action: Analgesia: inhibits formation of prostaglandins invlolved with pain. It is important to understand for the nclex, that an analgesia acts on the body by acting on the hypothalamus and blocking the generation of the pain impulses.  An antipyretic inhibits the formation of prostaglandins in production of fever.  The aspirin acts on the hypothalamus (as you remember from nursing school, is the thermostat on the body).   What it can do when inside the body: It is used for moderate pain, control fever, it is also used as an anti inflammatory and helps reduce the risk for MI in men with unstable angina.

  • Adverse reaction includes: tinnitus, confusion, dizziness, drowiness and bleeding (this is big for the nclex).
  • Other type of non narcotic analgesic: Acetaminophen (Tylenol).

A sample nclex review question:

  • Which condition is an indication for aspirin use?
  • 1. Asthma
  • 2. TIA    (correct answer) due to aspirin’s antiplatelet effect, aspirin can be use to decrease TIA.
  • 3.  Gout
  • 4. Nasal Polyps

Other Nonsteroidal Anti-Inflammatory Drugs (NSAIDS) for the nclex includes:

  • Ibuprofen
  • Indomethacin (Indocin)
  • Ketorolac (Toradol)
  • Celecoxib (Celebrex)

Now we can talk about Narcotic Analgesics:

One of the most commonly used Narcotic Analgesic in the nclex is morphine or morphine sulfate:

  • Morphine Sulfate: acts on opiod receptors in the CNS and induces sedation, analgesia, and euphoria.  It is used to relief moderate to severe pain. Such as pain from an MI or myocardial infarction (big in the nclex).
  • Adverse effects can include: sedation, confusion, euphoria and impaired coordination.   A big adverse reaction to know (nclex) is respiratory depression, hypotension, tachycardia and bradycardia.
  • Observe for signs of tolerance with prolonged use  (nclex)
  • monitor respiratory rate and depth before giving the drug and periodically thereafter. (nclex)
  • Always remember to have narcotic antagonist (naloxone) Narcan available on hand.
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