23. Pharmacology: Part 1 (-Anticonvulsants) Flashcards
Branch of medicine concerned with the USES, EFFECTS, and MODES OF ACTION of drugs
Pharmacology
Branch of pharmacology concerned with the EFFECTS OF DRUGS and the MECHANISM of their action (“action of drug on the body”)
Pharmacodynamics
Branch of pharmacology concerned with the MOVEMENT OF DRUGS within the body (“action of body to the drug”)
Pharmacokinetics
Pharmacokinetics steps: “ADME”
Absorption
Distribution
Metabolism
Excretion
Main site of absorption in the body
Jejunum of small intestine
BQ: Primary solubility of drug to be absorbed?
Form of drug that is EASY TO ABSORB
Lipid soluble form
Major site of metabolism
Liver
converts drugs into water soluble form to easily excreted by the kidney
Liver
Form of drug that is EASY to EXCRETE
Water soluble
Major site of excretion
Kidney
Study of drug’s harmful effects
Toxicology
General rule: Kailan nagiging toxic yung drug?
Pag na-“overdose”
Has “Adsorption” property (nagsstick sakanya yung toxins; diretso sa excretory system) to prevents ORALLY taken drugs TOXICITY
Activated charcoal
INDUCES VOMITING (emetic) ; can be used pag nasa GIT pa yung drugs na tinake para di na pumunta sa circulatory system
Syrup of Ipecac
BQ: It is the “accumulation of drug” because it cannot be excreted by the body?
Cumulation
“Cumulation” or accumulation of drug in the body is associated with what organ damage?
- Liver damage - clearance rate: ⬇️ (marereduce yung nacconvert na Lipid soluble ➡️ WATER soluble)
- Kidney damage - Normal yung liver:nacoconvert yung drug into water soluble BUT hard to excrete!
BQ: Drugs contraindicated for GLAUCOMA?
Diazepam
Anticholinergic drugs
BQ: What is the most common allergenic drug?
Penicillin
BQ: Drugs SAFE FOR PREGNANCY
Local anesthetics : lidocaine
Analgesics : biogesic
Sedative-Hypnotics
*AMOXICILLIN (safe!)
BQ: study of DAMAGE TO FETUS during development
Teratology
Most critical period of development of fetus?
1st trimester: organogenesis
Examples of Teratogenic drugs
- Tetracycline :tooth discoloration (til 8y/o)
- Thalidomide
- An anti cancer drug {no effect sa pregnant rats=no effect ; clinical trial=dysplastic tissues: bata kulang body parts}
BQ: study of drug DOSAGE
Posology
Process of DRUG UPTAKE from the site of administration towards the bloodstream
Absorption
“Enteral”
Oral
Rectal
“Parenteral” - uses needle
IV IM Intradermal Subcutaneous Intrathecal
Most common route; easy to administer
Oral route
Suppositories
Rectal
Route with 100% bioavailability; bypasses the first pass effect; “TOTAL ABSORPTION”
- (100ml inject = 100ml circulatory system)
Intravenous
Term: Dose ng drug na nakakarating sa circulatory system
Bioavailability
Most common site of IV administration
Antecubital region
BQ: Most common muscle used in IM administration
Vastus lateralis
Other muscles that can be used in IM administration
- Gluteus maximus - BQ: (“superolateral”/upper outer corner)
- Deltoid
Used during skin testing to determine if patient has drug allergy
Intradermal
Why intradermal during skin test?
Least and slow absorption
administration of drug in the SPINAL
Intrathecal
Fastest route if the target site is the BRAIN; (sedation)
Inhalational
Degree of needle insertion in IV
35 degrees
Degree of needle insertion in IM
90 degrees
Degree of needle insertion in Intradermal
0 - 15
{sa boards: piliin yung LOWEST value}
Degree of needle insertion in Subcutaneous
45 degrees
Most common drug administered subcutaneously
Insulin
BQ: Which route bypasses membranes?
Intravenous
- diretso na sa circulatory system
BQ: Which route bypasses ABSORPTION process?
IV
- distribution na agad
Drug properties that influence absorption
Must be “weak acids / weak bases”
- they become MORE LIPID SOLUBLE (mas madali iabsorb sa circulatory system)
ph of blood = 7.4
✨ WEAK ACIDS (pH of 6)
- weak acids are attracted to HIGHER pH levels
- 6 ❤️ 7.4
✨ WEAK BASES (ph of 8)
- weak bases are attracted to LOWER pH levels
- 8 💜 7.4
Amount of drug that reaches the circulatory system after administration
Bioavailability
Synonymous terms to “water soluble” drugs
Hydrophilic
Lipid INSOLUBLE
Ionized
Synonymous terms to “lipid soluble”
Fat soluble
Hydrophobic
Water INSOLUBLE
UNionized
Drug solubility that is UNABLE to cross the PHOSPHOLIPID bilayer
Very hydrophilic (very water soluble) - hindi makakatagos sa membrane
Solubility of drug that is UNABLE to be absorb due to INSOLUBILITY IN AQUEOUS FLUID
Very very hydrophobic/lipid soluble
- insoluble sa aqueous fluid ng intestinal area: hindi nalulusaw sa tubig
In reality: What must be the “drug’s solubility” to be absorbed?
Drugs must be SLIGHTLY HYDROPHILIC and LARGELY HYDROPHOBIC
Mej water soluble pero MAS lipid soluble
BQ: Primary solubility of drug to be absorbed (sa boards)
Lipid soluble
Phenomenon of drug metabolism whereby the CONCENTRATION OF ORALLY TAKEN DRUGS IS REDUCED before reaching the systemic circulation
First pass effect
Responsible for First Pass Effect
Liver
- dadaan muna yung drug sa portal vein to liver(metabolizes drug) bago makarating sa target site
Bioavailability is influenced by (3):
Drug solubility
Route
First pass effect
Ability of drug to move from circulatory system into their target sites
(- Once na pumasok na sa blood stream)
Distribution
Once the pumasok drug sa circulatory system: Meron 2 forms: (active and inactive)
- Free ionized drug - may effect agad; free floating drug
2. Bound drug - reserve; bounded to albumin
Most common binding site of drugs?
Albumin
Tendency of a substance to separate or dissociate from its binding
Dissociation constant (Kd)
Lower Kd ⬇️:
Separation -
Duration of effect -
Onset of action -
Lower Kd ⬇️:
Separation - lesser ⬇️
Duration of effect - longer
Onset of action - slower distribution
Higher Kd ⬆️:
Separation -
Duration of effect -
Onset of action -
Higher Kd ⬆️:
Separation - higher ⬆️
Duration of effect - shorter
Onset of action - faster distribution
BQ: Most important microsomal enzyme of Liver?
Cytochrome P450
FUNCTIONS OF LIVER
- Lipid soluble to lipid insoluble
- “Water soluble” easily excreted by the kidney - Active drug to INACTIVE drug
- detoxification (kasi yung hindi pwdeng magstay na active yung drug: kahit sya yung may effect, toxic pa din) - PRODRUGS ➡️ ACTIVE FORM
- prodrug = “inactive drug”
- para maconvert to active need muna mag pass sa LIVER
-
Examples of PRODRUGS (inactive drugs=no effect) that must go to the LIVER to be activated:
- Aspirin (Acetylsalicylic acid) ➡️ Salicylates
- Codeine ➡️ Morphine
- Alcohol ➡️ Ethanol
2 types of Local anesthesia:
Amide - “ii”
Ester - “i”
Metabolism of Local anesthetics: “EPAL”
Ester - Plasma
Amide - Liver
Most common topical anesthesia?
Benzocaine
Exception: dalawang “ii” PERO ester
piPEROcaine
Exception: Amide but metabolized in BOTH liver and plasma
Articaine - (“maarti” : metabolized sa liver and plasma)
BQ: local anesthesia used if allergic in both ester and amide
Diphenhydramine Hcl (Benadryl) - injected!!
BQ: Plasma enzyme (metabolism)
Plasma pseudocholinesterase
Drugs metabolized in PLASMA
Ester LA
Succinylcholine
BQ: primary use of succinylcholine
For laryngospasm
Major organ for excretion
Kidney
Drug excreted by the lungs
Nitrous oxide (laughing gas)
Drugs or substances excreted by BREAST MILK
Alcohol
Caffeine
Cocaine
Nicotine
Time required for a drug to REDUCE HALF of its initial value
Half life (t1/2)
Rate at which the active drug is removed from the body
Clearance
Amount of drug eliminated is CONSTANT and is NOT DEPENDENT on the CONCENTRATION of drug in plasma fluid
Zero order kinetics
- constant: clearance rate
- not constant: half life
Examples of drugs that follow ZERO ORDER KINETICS
Alcohol - (clearance rate=15ml/hr)
Phenytoin
Aspirin
Amount of drug eliminated is DEPENDENT on the CONCENTRATION of drug in plasma fluid (most drugs follow this)
First order kinetics
- may “constant half life”