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Physicochemical Properties of Drugs in relation to Drug Action. Roselyn A. Naranjo USPF, College of Pharmacy www.roselynnaranjo.vze.com [email protected]. DRUG-RECEPTOR INTERACTIONS. ORAL. Systemic Circulation. Intramuscular Subcutaneous Intravenous. DRUG-RECEPTOR INTERACTIONS. ORAL. - PowerPoint PPT Presentation
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Roselyn A. NaranjoUSPF, College of Pharmacy
Physicochemical Properties of Drugs in relation to Drug Action
DRUG-RECEPTOR INTERACTIONS
ORAL
IntramuscularSubcutaneousIntravenous
Systemic Circulation
DRUG-RECEPTOR INTERACTIONS
ORAL
IntramuscularSubcutaneousIntravenous
Systemic Circulation
DRUG-RECEPTOR INTERACTIONS
drug
+ =
good fit
Desired pharmacologic response
Favors irreversible reaction
more drug molecules are bounded
receptor
DRUG-RECEPTOR INTERACTIONS
drug receptor
+ =
poor fit
No response
Favors reversible reaction
Small amount of drug molecules are bounded
Ineffective drug
DRUG-RECEPTOR INTERACTIONS
Variables that affects drug binding
Structural class
3D shape of molecule
Type of chemical bonds
- OH – O = \ / C - OH - ll C / \
DRUG-RECEPTOR INTERACTIONS
Drugs with the same Pharmacologic class & structural features
Barbiturates
DRUGSDRUGS RECEPTOR SITERECEPTOR SITE EFFECTEFFECT
Specific CNS receptors
Depressant effects Hydantoin Specific CNS
receptors Anticonvulsant
response
Benzodiazepines
GABA receptors Anxiolytic activity
Penicillin Specific enzymes Inhibit bacterial
cell wall construction
Cephalosporins
Tetracyclines Bacterial wall ribosomes
Inhibit bacterial cell wall construction
DRUG-RECEPTOR INTERACTIONS
RECEPTORS First Receptor Model Enzymes
• Acetylcholinesterase
• Dihydrofolate reductase
• Angiotensin
• HIV protease-converting enzymes
H H O \ l ll N – C – C - OH / lH R
H
DRUG-RECEPTOR INTERACTIONS
RECEPTORS Proteins
Amine group
Acid group
Alkyl group
(-)(+)H
Amine group
- receptors are not distributed equally
- behave differently
DRUG-RECEPTOR INTERACTIONS
RECEPTORS ProteinsDrug therapy
Produce 2 effects
Pharmacologic response
Adverse reactions
DRUG-RECEPTOR INTERACTIONS
RECEPTORS ProteinsExample
Paste tamoxifen Structure
here
For estrogen-sensitive breast cancer
For reducing bone loss from osteoporosis
Pharmacologic response Prolonged treatment results to
endometrial cancer due to the response of estrogen
uterine receptors
Adverse effect
ANTAGONIST in the
Mammary Gland
AGONIST in the Uterus &
Bone
DRUG-RECEPTOR INTERACTIONS
RECEPTORS ProteinsExample
Paste sildenafil Structure
here
Inhibit phosphodiesterase that would treat angina
Expected effect Effective inhibitor of an enzyme
found in the corpus cavernosum
Unexpected Results
NO EFFECT in Angina
EFFECTIVE in erectile
dysfunction Vasodilate the blood vessels in the male organ that leads to penile erection
DRUG-RECEPTOR INTERACTIONS
Biological response
Biological receptor site
Bonding forceBonding force
FORCES INVOLVED
DRUG-RECEPTOR INTERACTIONS
Biological response
Bonding forceBonding force
Ionic bond/weaker
Covalent bond/stronger
-short-acting-reversile
-long-lasting effect-irreversible
FORCES INVOLVED
DRUG-RECEPTOR INTERACTIONS
Types of Chemical Bonds
Bond Type Bond Strength example
Covalent 40 – 140 CH3 – OH
Reinforced Ionic 10
Ionic 5 R4 N ---- I
H lR-N-H-O l C - R’ H O
(+)---(-)
(+)---(-)
DRUG-RECEPTOR INTERACTIONS
Types of Chemical Bonds
Bond Type Bond Strength example
Hydrogen 1 – 7
Ion-dipole 1 - 7 R4 N ----:NR3
Dipole-dipole 1 - 7
- OH – O = \ / C - OH - ll C / \
lO = C ....:NR3
lδ- δ+
DRUG-RECEPTOR INTERACTIONS
Cis & trans structure formation
FORCES INVOLVED