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ثباحو
مفيش حاجه مهمه المره دي
ركز اكتر او احفظ اللي تحتو خط
طبعا لازم تكون فاهم الموضوع
pharmacology is subdivided into ? (2)
pharmacokinetics and pharmacodynamics
pharmacokinetics means ?
effect of the body on the drug
pharmacodynamics means ?
effect of the drug on the body
pharmacokinetics is divided into 4 stages ?
اربع مراحل اي هما بقا
(مختصرين في كلمه لو فاكر)
(ADME )
• Absorption
• Distribution
• Metabolism
• Excretion
what are the 3 clinical importance of pharmacokinetics ?
what does drug absorption means ? (def.)
and what are the 2 categories of factors affecting drug absorption
absorption is the transfer of drug from site of administration to blood stream
.
factors affecting drug absorption are:
1-factors related to the drug
2-factors related to the patient
مش احسن صيغه لللجزء التاني بس حاولت اقربها قد ما اقدر
what are the 3 factors affecting drug absorption related to the drug ?
• Lipid solubility: lipid soluble drugs are more readily absorbed.
• Degree of ionization; the greater the lesser the absorption.
• Stability of gastric acid and digestive enzymes (benzyl- penicillin and insulin are destroyed in GIT) في الاخيره يقصد هو يستحمل وجوده في المعده مثلا من غير ما يتهضم او كدا
what are the 3 factors affecting drug absorption related to the patient ?
• Route of administration: I.V is the fastest.
• Absorbing surface area.
• Specific factors: Intrinsic factor is needed for Vitamin B12 absorption.
what happens if we put a basic drug in a basic media or
an acidic drug in an acidic media
it will be unionized so it will be lipid soluble
what happens if we put a basic drug in an acidic media or an acidic drug in a basic media ?
it will be ionized so it will be less lipid soluble
relation between ionization of the drug and its lipid solubility ?
what is the nature of most drugs (acidic,basic كدا يعني)
Unionized drugs (uncharged) are more lipid soluble and more easily absorbed and vise versa
.
most drugs are weak bases or weak acids
pKa is ?
قوله ك كونسيبت مره و
ك قانون تاني مره
• pKa is the pH at which 50% of the drug is ionized and 50% is unionized
.
Pka (of the drug) = PH (of the media) + log unionized /ionized.
طبعا لو قدامنا مثلا حاجه ال pka بتاعها
3.5
لو قللنا ال ph عن 3.5
امتصاصه هيزيد والعكس صحيح
name the 3 Clinical significance of pKa and pH
الاسم بس
1- Knowing site of drug absorption
2- Ion trapping
3- Treatment of drug toxicity
Clinical significance of pKa and pH:
1- Knowing site of drug absorption:
اشرحها بقا
Acidic drugs as aspirin are largely unionized in gastric acidic PH and are absorbed from stomach, while bases, e.g., atropine are largely ionized (في المعده يعني) and are absorbed only when they reach the intestines.
Clinical significance of pKa and pH:
2- ion trapping
اشرحه بقا
مثال ال aspirin & stomach
Acidic drugs as aspirin are largely unionized in gastric lumen (معناها هيمتص بسهوله) which is acidic, so aspirin passes into cells lining stomach. But once entered cells finds the pH is alkaline where it is ionized and trapped.اول ما يدخل خلايا المعده نفسه اللي هي البطانه بتاعت المعده يعني
هيبقي TRAPPED جوا
عشان ال PH بتاعها عالي ALKALINE
Clinical significance of pKa and pH:
3-treatment of drug toxicity
اشرحه بقا
حلاوه الكروت هنا بقا
كلنا حافظين الكلام اللي جوا او فاهمين الكلام اللي جوا
اربطه بالعنوان بقا هتعرف لازمته اي في الحياه الحقيقيه
clinical significance
- Alkalization of urine decreases renal reabsorption,
so increase renal excretion of acid drugs. e.g., Aspirin.
- Acidification of urine increase renal excretion of basic drugs.
فايده الكلام دا ان لو حد خد جرعه اوفر من دوا acidic
نقدر نديله دوا يزود ال alkalinity بتاعت ال Urine
ساعتها نعرف نخرج الدوا دا من الجسم اللي ساعتها هيكون الشخص واخد جرعه سامه
what is first pass metabolism (presystolic elimination)
Metabolism of drugs in site of administration before reaching systemic circulation. e.g., GIT or liver after oral administration.
what is gut first pass effect (2) مثال علي كل واحده بليز
- Gastric acidity: destroys benzyl penicillin
- Digestive enzymes: destroy insulin.
example of Hepatic first pass effect
nitroglycerine
مبيعديش يعني عشان كدا لازم يتاخد
sublingual عشان يروح
لل circulation علي طول
how to avoid high first pass effect ?
- change the route of drug administration. ex,. Give nitroglycerine sublingual.
انسولين حقن كدا
- increase the oral dose
what is bioavailability ?
bioavailability in IV administration ?
• It is the fraction of the drug that reaches the systemic circulation in the unchanged form.
• Bioavailability is 100% after IV administration.
لو انا اخدت 100 ميللي جرام من دوا
ووصل للدم 70 ميللي جرام يبقي ال
bioavailability = 70%
what are the 2 factors affecting bioavailability
- Absorption: (The more the drug absorption the higher the bioavailability)
-First pass metabolism: The more first pass metabolism, the less the bioavailability