Pharmacology Flashcards
Who monitors drugs for the potential of abuse
DEA (Drug enforcement agency)
Drug schedules
I) Highest- No accepted medical use (heroin, LSD)
II) High- Rx required, opioid narcotics (oxycodone, morphine, hydrocodone)
III) Moderate- Rx required, codeine mixtures (Tylenol 3)
IV) Less- Rx required, anti anxiety, sleeping meds, tramadol
V) Least- No Rx required, codeine containing cough syrups
Schedule II must be typed or written, require new written script for refill
Schedule III and IV can be telephoned to pharmacy 5 times in 6 months
As schedule number increases, abuse potential decreases
Potency vs efficacy
Potency: Amount of drug needed to produce therapeutic effect
Efficacy: Maximum intensity of effect produced by drug
Potency and efficacy are unrelated, drugs may have different potencies but not the same efficacy
Efficacy- Y axis
Potency- X axis
Agonist
Drug produces an effect and has affinity for receptor on cell membrane
Antagonist
Drug counteracts the action of agonist (blocks receptor)
ADME: Absorption
Drug transfer from sight of administration to blood stream
Lipid soluble and nonionized= Easily absorbed
The absorption phase is bypassed when a drug is administered intravenously
The most important site for drug absorption of orally administered drugs is the small intestine
ADME: Distribution
Drug distributed by blood plasma
Factors that influence distribution: Organ size and amount of blood flow, drug solubility, barriers
ADME: Metabolism
Body’s way of changing a drug so it can be excreted
Excreted product is ionized and less lipid soluble (opposite so body can excrete it)
Most common location is the liver. Patients with liver disease or alcoholism may have decreased ability to metabolize drugs. Leads to increased levels in blood which increases toxicity
ADME: Excretion
Drug can be excreted unchanged or as a metabolite (modified)
Kidney (renal) excretion is most common. Can also be excreted through lungs, saliva, breast milk, crevicular fluid
Lipid soluble drugs are not excreted in urine- must be metabolized by liverinto water soluble form to be excreted into urine
Major route of fluoride excretion is in urine
Half life first order kinetics
Constant PERCENTAGE of drug is removed from body per unit of time
(Shorter half life, shorter action of duration, etc)
Half life zero order kinetics
Constant AMOUNT of drug removed from body per unit of time (alcohol and aspirin)
High doses, very long duration of action
Enteral route
Drug placed directly in GI tract- orally or rectally
Drug levels less predictable with oral administration
First pass effect
Orally derived drugs must pass through hepatic portal circulation which can inactivate some drugs.
Amount of drug available to produce systemic effect is reduced by first pass effect
Drugs with high first pass effect require a larger oral dose as high percentage will be deactivated
Parenteral route
Bypasses GI tract
Injection
Inhalation
Topical- contraindicated if surface is ulcerated, burned or abraded
Therapeutic effect
Desirable action of drug
Adverse reaction
Undesirable action of drug
- Side effect: Expected but unwanted response, dose related, non target organs
Toxic reaction
Expected response, exaggeration of therapeutic effect, dose related, target organs
Allergic reaction
Not predicatable, not dose related,
Type I: Immediate hypersensitivity- anaphylaxis
Type IV: Delayed hypersensitivity- contact dermatitis (latex, TB test, transplant)
Therapeutic index
Lethal dose divided by effective dose (LD50/ED50)
Shows safety of drug
Narrow TI: Toxicity more likely
Wide TI: Toxicity less likely, safer drug
TI>10 needed for useful drug
When is epinephrine contraindicated
Cocaine or meth abuser
Clonidine
Adrenergic agonist
Meth
Oral mucosal irritation is a result of the method of drug administration, not the drug itself
Adrenergic drug contraindication
Uncontrolled hypertension and uncontrolled hyperthyroidism- avoid epi or use cardiac dose
Autonomic nervous system drugs
Adrenergic drugs: Mimics SANS
Cholinergic drugs: Mimics PANS
SLUD
Large doses of cholinergic drugs produce SLUD
Salivation, lacrimation, urination, defecation
Pilocarpine (salagen) treats xerostomia (pillow)
Cevimeline (evoxac) treats xerostomia (evacuate)
Atropine
Anticholinergic drug used pre operatively to decrease salivary flow for dental procedures
Non opioid analgesics (Non narcotics)
Mechanism of action: Inhibit prostaglandin synthesis
Prostaglandins: Sensitize pain receptors, lower pain threshold, cause inflammation and fever
Aspirin
NSAID, analgesic, antipyretic, anti-inflammatory, antiplatelet
Adverse reactions: GI irritation, can cause Reye syndrome in kids, contraindicated with warfarin, can cause white wrinkle of mucobuccal tissue where a patient might hold it in their mouth (aspirin burn)
Ibuprofen (Naproxen)
NSAID, most useful pain med in dentistry, analgesic, antipyretic, anti inflammatory, NOT antiplatelet
GI irritation. Contraindicated with warfarin, can decrease effects of many drugs such as ACE inhibitors, beta blockers, loop diuretics, corticosteroids, cyclosporine, lithium
Is taking NSAIDS with phenytoin (Dilantin) contraindicated?
Yes! Can increase phenytoin levels
(Seizure meds)
Acetaminophen (Tylenol)
No anti inflammatory action, NOT an NSAID
No effect on GI irritation, no effect on clotting
Analgesic, antipyretic
Patients with liver disease should avoid
Is drug of choice for patients on warfarin or peptic ulcers
Naloxone (narcan)
Parenteral opioid antagonist
Drug of choice for treating overdose
What is most common opioid used in dentistry
Codeine (Tylenol 3)
Codeine cannot be used in pregnant women (repiratory depression for neonatal fetus)
Sign of overdose or addiction: Pinpoint pupils
All opioids lead to constipation
Antiinfective agents
Stage 1: Initial stages of infection- Penicillin/amoxicillin
Stage 2: Mixed infection- Metronidazole or Clindamycin
Stage 3: Advanced infection- Metronidazole or Clindamycin
Mean Cleaners
Are antibiotics effective against bacterial or viral infections?
Bacterial
Antibiotic tips
Penicillin: High incidence of allergies
Antibiotics decrease the effectiveness of birth control pills
Increase effects of anticoagulants (warfarin)
Erythromycin: Highest incidence of GI complaints
Tetracycline: Contraindicated during pregnancy
Liquid forms have higher sugar content- advise kids to brush after
Most common allergic reaction is rash
Is penicillin VK preferred over penicillin G?
Yes! Penicillin G is inactivated by gastric acids
Augmentin
Augmentin= penicillin with clavulanic acid
Penicillin is not effective against penicillinase producing bacteria… BUT Augmentin is effective… it prevents penicillinase from breaking down amoxicillin
Cephalosporins
Very similar to penicillin but more expensive. If pt is allergic to penicillin they’re allergic to cephalosporins
Macrolides (-mycins)
Erythromycin: Increase effect of warfarin, most common side effect is GI upset
Azithromycin and clarithromycin: Both can be used for premedication if there is a penicillin allergy
Tetracycline (cyclines)
Don’t take with milk (binds with calcium)
Used to treat NUP/NUG and aggressive perio due to their excretion into the crevicular fluid where they have an anti collangenase effect
Photosensitivity
All tetracyclines cross placental barrier and are excreted in breast milk
Clindamycin
Can lead to C diff and severe persistent diarrhea
Nitroimidazoles
Effective against obligate anaerobes only
If alcohol is ingested, it will make you very sick, avoid listerine
Anti tuberculosis agents
Tx is difficult, treat with multiple drugs at the same time (RIPE)
Rifampin, isoniazid, pyrazinamide, ethambutol
If pt indicated they are taking rifampin or isoniazid only they are likely taking it as a preventative agent
Suggested premed
Single dose of 2000mg of amoxicillin 30-60mins before appt
If allergic- cephalexin 2000mg, macrolides or tetracyclines
Anti fungal agents (-azole)
Nystatin: Most commonly used in dentistry, topical drug used to treat candidiasis
Fluconazole (diflucan): oral drug to treat systemic infections
Anti viral drugs (-vir)
Most viruses do not require drug therapy and should “run their course” beside HIV
Aclovir topical
Local anesthetic preservative
Sodium bisulfate/sodium metabisulfate is the preservative (only is vasoconstrictor is present)
Contraindicated in patients with sulfite allergies or sensitivities
Local anesthetic mechanism of action
Inhibit influx of sodium ions
Function is lost in this order: Autonomic, temperature, pain, touch/pressure, vibration and motor, regain function in reverse order
Esters
No i before Caine
Metabolized in plasma/blood
High potential for allergic reactions
Not available in dental cartridges anymore
Benzocaine is an ester and available as a topical
Amides
Metabolized in liver
Lidocaine: Most commonly used in dentistry, safe in pregnancy and during lactation
Mepivacaine (carbo): Similar to lidocaine, plain or with epi
Prilocaine: Longer duration and lower epi content than lido, associated with methemoglobinemia
Bupivacaine: Greatly prolonged duration of action, indicated for lengthy procedures
Articaine (septo): Partially metabolized in liver (5-10%) and partially in blood (90-95%) can cause paresthesia after mandibular block, no absolute max
Duration of action of anesthetics (shortest to longest)
Mepivacaine
Lidocaine
Prilocaine
Articaine
Bupivacaine
Choosing your anesthetic
PKa (Onset of action): lower pKa=better absorbed
Protein binding capacity (duration of action): Stronger binding=longer duration
Lipid solubility (potency): more lipid soluble=more potent
Vasodilating properties (potency and duration of action): Less vasodilation=more potent and longer duration
Vasoconstrictors are added to anesthetics for:
Decreased systemic absorption- Lower risk for toxicity
Decreased absorption
Increased duration of action
Decreased bleeding
Healthy and cardiac dose of epi
Healthy: 0.2mg epi per appt
Cardiac: 0.04mg epi per appt (pregnancy, diabetes, hypertension)
Which anesthetics are available without a vasoconstrictor
Lidocaine (not available in US)
Mepivacaine
Prilocaine
Benzodiazepines (-Pam, -lam)
Anti anxiety drug, fast acting, wide TI, causes sedation, no analgesic effect
Barbiturates (-tal)
Long acting and narrow TI, produces CNS depression, no analgesic effect, used for anticonvulsant and to induce general anesthesia
Nitrous oxide
Low solubility in blood, nitrous tank is blue while oxygen tank is green, excreted by inhalation, no biotransformation (inhaled and exhaled in same form), place pt on 100% oxygen for 5 mins following procedure to prevent headache, nitrous maintains pt in stage I anesthesia, can reduce orofacial muscle tone in cerebral palsy patients, can lead to neurological symptoms similar to Parkinson’s/demetia
What symptoms accompanies all antidepressant drugs
Xerostomia
Antidepressant drugs
SSRIs
SNRIs
TCAs, (Do not use epi in patients taking TCAs- may lead to hypertensive crisis. If must, use cardiac dose)
MAOIs
Other: bupropion (Wellbutrin) and lithium
Anticonvulsant drugs
Phenytoin (Dilantin): gingival enlargement in 50% of chronic users
Benzodiazepines: Diazepam (Valium) is drug of choice for status epilepticus which can be caused by local anesthetic overdose
Antihypertensive drugs
Diuretics:
Thiazide diuretics: HCTZ is most common, causes xerostomia and treats high bp
Loop diuretics: furosemide most common
ACE inhibitors (-pril)
Antihypertensive drugs, blocks ACE, dry hacking cough, effectiveness reduced by NSAIDS
Angiotensin receptor blockers (ARBs) (-sartan)
Antihypertensive drug, more specific than ACE so less side effects, effectiveness reduced by NSAIDS
Calcium channel blockers
Antihypertensive drug, effectiveness NOT reduced by NSAIDS, gingival enlargement
Ex: AMlodipine, verapamil, nifedipine (HIGH probability of gingival enlargement), diltiazem
Always Very Nice Day… except with gingival enlargement
Beta blockers (-olol)
Antihypertensive drug. Epi should not be used on patients taking non specific beta blockers such as propranolol, can result in greatly increased vasopressor response causing hypertension. Avoid epi or use cardiac dose
Alpha blockers (-zosin)
Orthostatic hypotension does NOT cause blood pressure to quickly rise, the BP drops
When is nitroglycerin contraindicated in an angina attack
If pt has taken erectile dysfunction drug in last 24 hrs
Antihyperlipidemic drugs (-statin)
Lowers levels of cholesterol
Anticoagulation drugs
Reduce intra vascular clotting
Antibiotics can increase bleeding effects of warfarin (due to effects on vitamin K)
Plavix is used to prevent blood clots after MI or stroke
Heparin is one of most used anticoagulants used in Hospitalized patients (injection)
GI drugs board alerts
Pt on Tagamet likely being treated for gastric ulcers
Gastric ulcers do not cause gingival bleeding
Enamel erosion on ant max linguals indicate GERD
Respiratory drugs board alert
Aspirin should be avoided in asthmatics- increased risk of aspirin hypersensitivity
Albuterol can cause insomnia
Corticosteroid inhalers can lead to thrush- rinse with water after
