Материал: MasterPass _ Pharmacology in 7 Days for Medical Students

GENERAL PHARMACOLOGY

•Miscellaneous drugs: aminophylline 6 mg/kg I/V or metaraminol 1.5–5 mg I/V.

•Supportive treatment: I/V fluids, oxygen, tracheostomy, endotracheal intubation.

Drugs that can cause anaphylaxis

Horse serum, penicillins, cephalosporins, plasma expanders (dextran; polygeline), parenteral vitamin B complex, aminoglycosides, amphotericin B, L-asparaginase.

WHO deÞnition of drug dependence

Drug dependence is a psychological or sometimes physical state resulting from the interaction between a living organism and a drug, characterised by behavioural and other responses that always include a compulsion to take the drug on a continuous or periodic basis in order to experience its psychological/ physical effects and sometimes to avoid the discomfort of its absence.

Tolerance may or may not be present. A person may be dependent on more than one drug.

Components of drug dependence

Euphoria, tolerance, psychological/physical dependence and withdrawal syndrome.

Drugs causing drug dependence

Drugs causing severe psychological or physical dependence: Examples include morphine, codeine, pethidine, methadone, benzodiazepine, barbiturates, amphetamines and ethyl alcohol.

Drugs causing psychological dependence only: Examples include cocaine, cannabis, nicotine, caffeine and LSD.

Management of drug dependence

1Gradual or sudden withdrawal of the drug.

2Substitution therapy.

3Specific drug therapy.

4Psychotherapy.

5Occupational therapy.

6Correction of nutritional deficiencies.

7Community treatment and rehabilitation.

Bioavailability of drugs

‘Bioavailability’ means availability of a biologically active drug in a biologic system, especially at the site of action. It is the fraction of the drug/dose of the drug that reaches the systemic circulation in unchanged active form after administration by any route of a pharmaceutical preparation containing that active drug.

Factors affecting bioavailability

1Quality control in manufacturing and formulation.

2All factors affecting absorption of the drug from the GIT.

3First pass metabolism.

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PHARMACOLOGY IN 7 DAYS FOR MEDICAL STUDENTS

Dose-response curve

It is the graphical representation of the relationship between the dose of a drug and the response to a drug within a biological system.

Types

Graded dose-response curve: It is the quantitative curve in which increasing doses of a drug produces varying changes and effects.

Quantal dose-response curve: It is a curve that describes the distribution of minimum doses that produce a given effect in a population of test animals.

Cumulative dose-response curve: The numbers of determination are cumulatively added until all are accounted for.

Median effective dose: It is the dose of a drug required to produce a specified intensity of effect in 50% of the individuals. It is abbreviated as ED50.

Median lethal dose: It is the dose of a drug required to kill 50% of experimented animals. It is abbreviated as LD50. It is the measure to toxicity of a drug.

Therapeutic index (TI): It is the ratio of LD50 to ED50.

TI = LD50/ED50.

Plasma half-life (t¹Ú²)

DeÞnition

It is the time required for the concentration of a drug in the plasma to decrease to onehalf of its initial value after the steady state plasma concentration has been achieved.

t½ = 0.7 × Vd

CL

Vd: volume of distribution; CL: clearance of drug.

CL = rate of elimination of drug plasma drug concentration

Factors affecting t½

1Type of kinetics – zero or first order.

2Enzyme inhibitors (→ ↓ metabolism → ↑ plasma t½).

3Enzyme inducers (→ ↑ metabolism → ↓ t½).

4Active metabolites (→ ↑ t½ of a drug).

5Enterohepatic recirculation of a drug (→ ↑ t½).

6Diseases of organs of elimination – liver and kidney (↑ t½).

7Changes in the rate of blood flow to organs of elimination – liver and kidney.

8Displacement of drug from plasma protein binding (PPB) sites (↑ Vd → ↑ t½).

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2

Classifications

Adrenergic drugs

AChemical classification

1Catecholamines

iNatural

•Adrenaline

•Dopamine

•Noradrenaline

iiSynthetic

•Dobutamine

•Isoetherine

•Isoprenaline

•Hexaprenaline

•Rimiterol

2Non-catecholamines

•Amphetamine

•Dexamphetamine

•Ephedrine

•Metaraminol

•Pseudoephedrine

•Terbutaline

BClassification based on mechanism of action

1Both directly and indirectly acting sympathomimetics

•Ephedrine

•Metaraminol

2Directly acting sympathomimetics

•Adrenaline

•Isoprenaline

•Noradrenaline

•Salbutamol

•Terbutaline

3Indirectly acting sympathomimetics

iRelease of noradrenaline

•Amphetamine

•Methylamphetamine

•Tyramine

iiReuptake inhibitors

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PHARMACOLOGY IN 7 DAYS FOR MEDICAL STUDENTS

•Cocaine

•Tricyclic antidepressants

CClassification based on receptor selectivity

1Mainly α-receptor agonists

iα1-agonists

•Methoxamine

•Phenylephrine

•Xylometazoline

iiα2-agonists

•α-methyldopa

•Clonidine

iiiα1 and α2 combined agonists

•Oxymetazoline

2Mainly β-receptor agonists

iβ1 agonists

•Dobutamine

•Prenalterol

iiβ2 agonists

•Fenterol

•Ritodrine

•Salbutamol

•Terbutaline

iiiSelective β1 and β2 agonists

•Isoprenaline

•Orciprenaline

3α and β agonists

•Adrenaline

•Amphetamine

•Ephedrine

•Noradrenaline

4Adrenergic and dopaminergic agonists

•Dopamine

Cephalosporin generations (classiÞcation based on spectrum of antimicrobial activity)

1st Generation

•Cephalexin

•Cephradine

•Cefadroxil

•Cefazolin

2nd Generation

•Cefaclor

•Cefamandole

•Cefprozil

•Cefoxitin

•Cefuroxime

3rd Generation

•Cefixime

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CLASSIFICATIONS

•Cefoperazone

•Ceftazidime

•Ceftizoxime

•Ceftriaxone

4th Generation

•Cefepime

Chemical classiÞcation of antidepressants (TCA)

1Dibenzepines

•Imipramine

•Desipramine

•Trimipramine

2Dibenzoxepine

•Doxepine

3Dibenzoxazepine

•Amoxapine

4Dibenzocycloheptadienes

•Amitriptyline

•Nortriptyline

5Dibenzocycloheptatriene

•Protriptyline

6Miscellaneous

•Maprotiline

Chemical classiÞcation of anti-epileptic drugs

1Long-acting barbiturates

•Phenobarbitone

•Methyl phenobarbitone

2Deoxybarbiturates

•Primidone

3Benzodiazepines

•Diazepam

•Clonazepam

•Lorazepam

•Nitrazepam

4Hydantoin derivatives

•Phenytoin

•Mephenytoin

•Ethotoin

5Valproic acid derivatives

•Valproic acid

•Sodium valproate

6Iminostilbines

•Carbamazepine

•Oxcarbamazepine

7Succinimides

•Ethosuximide

•Phensuximide

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