PHARMACOKINETICS- Konti lang nmn lumabas tungkol sa kinetics sa board, masasagot mo tlga lahat ngtanong sa kinetics kung a...
-tingnan mo ung nsa gintang barrier, yan ang CELL MEMBRANE, mas naabsorb niya mgaLIPID SOLUBLE DRUGS. Yung mga water solub...
IONIZED and NONIONIZEDPartition CoEfficient- Ratio of concentrations of compound in a mixture of two immisciblephases or l...
LAWS TO REMEMBERFick’s law- DIFFUSIONMichaelis menten- saturation kineticsHenderson-hasselbach- Ionized/Non Ionized specie...
- So pag merong drug, mas mabilis sila mapapunta sa mga HIGHLY PERFUSEDTISSUES/ORGAN- BLOOD BRAIN BARRIER- Mahalaga mo din...
Basic Principles of Pharmacokinetics (Guide for Pharmacy Board Exam Takers in the Philippines)
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Basic Principles of Pharmacokinetics (Guide for Pharmacy Board Exam Takers in the Philippines)

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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.

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Basic Principles of Pharmacokinetics (Guide for Pharmacy Board Exam Takers in the Philippines)

  1. 1. PHARMACOKINETICS- Konti lang nmn lumabas tungkol sa kinetics sa board, masasagot mo tlga lahat ngtanong 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,reabsorptionPRINCIPLES NA DAPAT MONG TANDAAN (MAHALAGA TONG MGA TO)IONIZED MOIETY- WATER SOLUBLENON- IONIZED MOIETY- LIPID SOLUBLEDRUG TRANSPORTPASSIVE DIFFUSION- diffusion of nonionized moiety to a LIPID MEMBRANE from an area of highconcentration to low concentration (follows concentration gradient).- Yan ang pinaka simpleng transport mechanism, mag imagine ka na lng ng dalawang botena magkadikit, pag napuno ng tubig ung isang lalagyan, pupunta ung ibang tubig sakabilang lalagyan kasi di na kasya. Ganon dn pag ung drug nasa intestines, mataasconcentration ng gamot sa intestines kaya maabsorb sila pero tandaan mo, mas mabilismaabsorb ang mga LIPID soluble or NONIONIZED MOIETY kasi lipid soluble mga cellmembrane sa surface ng intestines.
  2. 2. -tingnan mo ung nsa gintang barrier, yan ang CELL MEMBRANE, mas naabsorb niya mgaLIPID SOLUBLE DRUGS. Yung mga water soluble naman, dumadaan sa PORES andCHANNELS ng cell membrane, konti lang nakakapasok sa mga pores and channels kayakonti 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, kelanganmapuno muna yung isang lalagyan para mapapunta sila sa kabila, pag ACTIVETRANSPORT hnd na kelangang mapuno, itatransport na kaagad ung laman ng isangcontainer sa kabila, syempre pag shortcut, me bayad, kaya kelangan ng ENERGY- Active transport is saturable and carrier mediated ( ang pinagkaiba dn ng active sapassive, merong CARRIER ang active para makagalaw siya, kasi wla siyang tagatulak kasikonti lang sila, hnd tulad ng PASSIVE na siksikan sila kaya natutulak ung iba sa ibanglugar. Ung mga carrier, nauubos dn sila, pag merong lamang drug lahat ng CARRIERS naavailable, 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 noenergy and follows a concentration gradient (From High to Low concentration)- Kapareho lang niya ang passive diffusion na kelangan munang mapuno ung isanglalagyan para mapapunta ung umaapaw na laman sa ibang lalagyan. ANg pinagkaibanila, merong CARRIER ito at pwedeng maubos ung carrier, pero dahil naghihintay silangmapuno para makagalaw, hnd na kelangan ng energy.VESICULAR TRANSPORT SYSTEMS- Transport mechanisms in which cells form VESICLES to engulf drug particlesENDOCYTOSIS- malaki ung vesiclePINOCYTOSIS- malilit ung vesicles pero madami
  3. 3. IONIZED and NONIONIZEDPartition CoEfficient- Ratio of concentrations of compound in a mixture of two immisciblephases or liquid. (dinidetermine ng partition coefficient kung more LIPID SOLUBLE o moreWATER SOLUBLE)IONIZED- Dissociated Form, Water Soluble FormNON-IONIZED FOR- Undissociated Form, Lipid Soluble FormETO ANG TECHNIQUEACIDIC + ACIDIC = Non-IonizedBASIC + BASIC= Non- IonizedACIDIC + BASIC = IonizedBASIC + ACIDIC = IonizedALWAYS 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 asnonionized 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, masmaraming morphine na mageexist as nonionized kaya mas marami maabsorb sa intestinesNOTE: HINDI LANG pH ANG BASIS PARA MASABI KUNG GANO KADAMI ANG MAABSORB, BESTSITE OF ABSORPTION PA DN ANG INTESTINES DAHIL SA MARAMING FACTORS TULAD NGSURFACE AREA AT IBA PA.
  4. 4. LAWS TO REMEMBERFick’s law- DIFFUSIONMichaelis menten- saturation kineticsHenderson-hasselbach- Ionized/Non Ionized speciesLADMERLIBERATION- DISINTEGRATION- The breaking apart of the solid dosage form- DISSOLUTION- Solid dosage form into SOLUTIONABSORPTION- Most ACIDIC drugs are more absorbed in the STOMACH, while BASIC drugs are wellabsorbed 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 angdrug)- Low GI emptying rate mas matagal maabsorb drug, High GI emptying rate mas mabilisang 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 ididistributeDISTRIBUTION- Self explanatory ang definition nito. Ang tatandaan mo lng sa distribution ay BLOODFLOW at PROTEIN BINDING.- CAPILLARY PERMEABILITY- pag mataas ang permeability o pagdaloy ng dugo sa isangtissue 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. 5. - So pag merong drug, mas mabilis sila mapapunta sa mga HIGHLY PERFUSEDTISSUES/ORGAN- BLOOD BRAIN BARRIER- Mahalaga mo din na tandaan na me BLOOD BRAIN BARRIER nanagfifilter ng mga dapat pumasok sa blood flow ng brain, LIPID SOLUBLE langnakakapasok sa blood brain barrier.- PROTEIN BINDING- Binds to drug and act as depot. Nagbibind jan ang drugs pag nsablood stream na pra macontrol ung dami ng drugs na mageexert ng effect. Ung Freedrugs 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 yungconcentration ng drug dun sa receptor or tissue.- 2 types of PROTEINS- Albumin- for acidic drugs, Globulins-for basic drugsMETABOLISM- 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 madalingma eliminateEXCRETION- PRIMARE ROUTES OF EXCRETION- KIDNEYS, TAE, alam mo na yanREABSORPTION- Pag sa kidneys, kung ung drugs ACIDIC + URINE na ACIDIC = mag eexist sila as nonionized kaya marereabsorb sila, bago maeliminate dapat IONIZED FORM o WATERSOlUBLE bago ma eliminate- BASTA PAG NON IONIZED FORM ANG DRUG, NA REREABSORB SIYAIMPORTANT NOTESGREATEST BIOAVAILABILITY to LOWEST BIOAVAILABILITYParental, Liquid dosage form, Sublingual, Capsule, Tablet

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