This discusses the basic principles to remember in pharmacokinetics. Some parts of the discussion is in filipino. This is a good guide for those who are about to take the board exams.

1. PHARMACOKINETICS
- Konti lang nmn lumabas tungkol sa kinetics sa board, masasagot mo tlga lahat ng
tanong sa kinetics kung alam mo tlga ung mga principles
- What the BODY does to the DRUG
- Study of the disposition or fate of the drug in the body
- LADMER- Liberation,absorption,distribution,metabolism,excretion,reabsorption
PRINCIPLES NA DAPAT MONG TANDAAN (MAHALAGA TONG MGA TO)
IONIZED MOIETY- WATER SOLUBLE
NON- IONIZED MOIETY- LIPID SOLUBLE
DRUG TRANSPORT
PASSIVE DIFFUSION- diffusion of nonionized moiety to a LIPID MEMBRANE from an area of high
concentration to low concentration (follows concentration gradient).
- Yan ang pinaka simpleng transport mechanism, mag imagine ka na lng ng dalawang bote
na magkadikit, pag napuno ng tubig ung isang lalagyan, pupunta ung ibang tubig sa
kabilang lalagyan kasi di na kasya. Ganon dn pag ung drug nasa intestines, mataas
concentration ng gamot sa intestines kaya maabsorb sila pero tandaan mo, mas mabilis
maabsorb ang mga LIPID soluble or NONIONIZED MOIETY kasi lipid soluble mga cell
membrane sa surface ng intestines.

2. -tingnan mo ung nsa gintang barrier, yan ang CELL MEMBRANE, mas naabsorb niya mga
LIPID SOLUBLE DRUGS. Yung mga water soluble naman, dumadaan sa PORES and
CHANNELS ng cell membrane, konti lang nakakapasok sa mga pores and channels kaya
konti ang naabsorb na water soluble drugs.
ACTIVE TRANSPORT- transport of drugs from LOW concentration to HIGH concentration
(against concentration gradient)
- Requires energy ( imagine mo ulit ung 2 lalagyan na magkadikit, sa passive, kelangan
mapuno muna yung isang lalagyan para mapapunta sila sa kabila, pag ACTIVE
TRANSPORT hnd na kelangang mapuno, itatransport na kaagad ung laman ng isang
container sa kabila, syempre pag shortcut, me bayad, kaya kelangan ng ENERGY
- Active transport is saturable and carrier mediated ( ang pinagkaiba dn ng active sa
passive, merong CARRIER ang active para makagalaw siya, kasi wla siyang tagatulak kasi
konti lang sila, hnd tulad ng PASSIVE na siksikan sila kaya natutulak ung iba sa ibang
lugar. Ung mga carrier, nauubos dn sila, pag merong lamang drug lahat ng CARRIERS na
available, hnd nakakasakay ung iba kaya SATURABLE SIYA.
- Selective for chemical structure.
CARRIER MEDIATED (FACILITATED DIFFUSION)
- A type of transport mechanism that is carrier mediated, saturable but requires no
energy and follows a concentration gradient (From High to Low concentration)
- Kapareho lang niya ang passive diffusion na kelangan munang mapuno ung isang
lalagyan para mapapunta ung umaapaw na laman sa ibang lalagyan. ANg pinagkaiba
nila, merong CARRIER ito at pwedeng maubos ung carrier, pero dahil naghihintay silang
mapuno para makagalaw, hnd na kelangan ng energy.
VESICULAR TRANSPORT SYSTEMS
- Transport mechanisms in which cells form VESICLES to engulf drug particles
ENDOCYTOSIS- malaki ung vesicle
PINOCYTOSIS- malilit ung vesicles pero madami

3. IONIZED and NONIONIZED
Partition CoEfficient- Ratio of concentrations of compound in a mixture of two immiscible
phases or liquid. (dinidetermine ng partition coefficient kung more LIPID SOLUBLE o more
WATER SOLUBLE)
IONIZED- Dissociated Form, Water Soluble Form
NON-IONIZED FOR- Undissociated Form, Lipid Soluble Form
ETO ANG TECHNIQUE
ACIDIC + ACIDIC = Non-Ionized
BASIC + BASIC= Non- Ionized
ACIDIC + BASIC = Ionized
BASIC + ACIDIC = Ionized
ALWAYS REMEMBER “NON IONIZED, BETTER ABSORBED” “IONIZED, EASILY ELIMINATED”
For example: Aspirin Pka= 3 (PKa, parang pH na dn yan nung substance) so acidic ung aspirin,
napapunta siya sa stomach na ang pH ay 2 or 3, acidic dn, maraming aspirin ang mag eexist as
nonionized so mas maabsorb siya sa stomach (PS, pwde dn magabsorb ng drugs ang stomach)
Another example: Morphine pKa= 8, basic siya, nakarating siya sa intestines pH 9, mas
maraming morphine na mageexist as nonionized kaya mas marami maabsorb sa intestines
NOTE: HINDI LANG pH ANG BASIS PARA MASABI KUNG GANO KADAMI ANG MAABSORB, BEST
SITE OF ABSORPTION PA DN ANG INTESTINES DAHIL SA MARAMING FACTORS TULAD NG
SURFACE AREA AT IBA PA.

4. LAWS TO REMEMBER
Fick’s law- DIFFUSION
Michaelis menten- saturation kinetics
Henderson-hasselbach- Ionized/Non Ionized species
LADMER
LIBERATION
- DISINTEGRATION- The breaking apart of the solid dosage form
- DISSOLUTION- Solid dosage form into SOLUTION
ABSORPTION
- Most ACIDIC drugs are more absorbed in the STOMACH, while BASIC drugs are well
absorbed in the SMALL INTESTINES (Alam mo na kung bakit)
- Low PARTICLE SIZE (Maliit), more absorbed (Common sense)
- Large SURFACE AREA (Malawak ang paligid ng drug) more absorbed (Low PARTICLE SIZE
= Large SURFACE AREA)
- GI EMPTYING (Pag me pagkaen sa tyan, d kaagad nakakapunta sa small intestines ang
drug)
- Low GI emptying rate mas matagal maabsorb drug, High GI emptying rate mas mabilis
ang absorption
- Short GI transit time mas mabilis maabsorb, Long GI transit time, mabagal maabsorb
- VILLI- found in the intestines that absorb drugs
- Maabsorb ang drugs sa bloodstream at ididistribute
DISTRIBUTION
- Self explanatory ang definition nito. Ang tatandaan mo lng sa distribution ay BLOOD
FLOW at PROTEIN BINDING.
- CAPILLARY PERMEABILITY- pag mataas ang permeability o pagdaloy ng dugo sa isang
tissue o organ, mas mabilis madistribute ung drug.
- HIGHLY PERFUSED ORGANS/TISSUES-
Brain,Heart,Lungs,Kidneys,Stomach,Liver,Intestines Etc.
- POORLY PERFUSED ORGANS/TISSUES- Fat,Bones,Muscle

5. - So pag merong drug, mas mabilis sila mapapunta sa mga HIGHLY PERFUSED
TISSUES/ORGAN
- BLOOD BRAIN BARRIER- Mahalaga mo din na tandaan na me BLOOD BRAIN BARRIER na
nagfifilter ng mga dapat pumasok sa blood flow ng brain, LIPID SOLUBLE lang
nakakapasok sa blood brain barrier.
- PROTEIN BINDING- Binds to drug and act as depot. Nagbibind jan ang drugs pag nsa
blood stream na pra macontrol ung dami ng drugs na mageexert ng effect. Ung Free
drugs o yung walang nakabind na protein ang mag eexert ng action, ung mga BOUNDED,
nsa blood stream sila at hindi na eeliminate, magiging free lang sila pag bumaba yung
concentration ng drug dun sa receptor or tissue.
- 2 types of PROTEINS- Albumin- for acidic drugs, Globulins-for basic drugs
METABOLISM
- Tandaan mo lang yung mga phases
- Phase I (Oxidation,Reduction,Hydrolysis)
- Phase II (Conjugation Reactions)
- Ang purpose ng metabolism ay to INCREASE WATER SOLUBILITY ng drug para madaling
ma eliminate
EXCRETION
- PRIMARE ROUTES OF EXCRETION
- KIDNEYS, TAE, alam mo na yan
REABSORPTION
- Pag sa kidneys, kung ung drugs ACIDIC + URINE na ACIDIC = mag eexist sila as non
ionized kaya marereabsorb sila, bago maeliminate dapat IONIZED FORM o WATER
SOlUBLE bago ma eliminate
- BASTA PAG NON IONIZED FORM ANG DRUG, NA REREABSORB SIYA
IMPORTANT NOTES
GREATEST BIOAVAILABILITY to LOWEST BIOAVAILABILITY
Parental, Liquid dosage form, Sublingual, Capsule, Tablet