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Pharmacology - NEETMDS- courses
NEET MDS Lessons
Pharmacology

Beta-Adrenergic blocking Agents 

• Prototype - Propranolol 
• Prevent or inhibit sympathetic stimulation
– Reduces heart rate
– Myocardial contractility 
– Reduce BP - decreases myocardial workload and O2 demand 
• In long-term management used to decrease frequency and severity of anginal attacks 
• Added when nitrates do not prevent anginal episodes 
• Prevents exercise induced tachycardia
• Onset of action 30 min after oral dose. 1-2 min IV

Therapeutic Actions
• Block Beta adrenergic receptors in the heart and juxtaglomerular apparatus 
• Decrease the influence of the sympathetic nervous system decreasing excitability of the heart 
• Decrease cardiac output. 
• Indicated for long term management of anginal pectoris caused by atherosclerosis 

Atenolol, metoprolol, and nadolol have the same actions, uses, and adverse effects as propranolol, but they have long half-lives and can be given once daily. They are excreted by the kidneys, and dosage must be reduced in clients with renal impairment.

DIURETICS

Specific Therapeutic Objective

Clinical State(s)

Drug(s) (Class)

Draw fluid from tissue to vascular space reduce tissue edema

Cerebral edema
glaucoma

Mannitol (Osmotic)
Glucose (Osmotic)
Glycerin (Osmotic)

Decrease renal swelling
expand tubular volume

Renal shutdown

Glucose (Osmotic)
Mannitol (Osmotic)

Modest and/or sustained decrease in venous hydrostatic pressure

Congestive heart failure
Hepatic cirrhosis
Udder edema

Hydrochlorothiazide (thiazide)
Chlorothiazide (thiazide)

Aggressive and/or short-term decrease in venous hydrostatic pressure

Congestive heart failure
Hepatic cirrhosis
Udder edema

Furosemide (loop)

Inhibit aldosterone action

Hepatic cirrhosis
Congestive heart failure

triamterene (K+ sparing)
spironolactone (K+ sparing - competitive)

Reduce potassium wasting 2o to other diuretic

Hepatic cirrhosis
Congestive heart failure

triamterene (K+ sparing)
spironolactone (K+ sparing - competitive)

Inhibit ADH action

Inappropriate ADH secretion

lithium (aquaretic)
demeclocycline (aquaretic

Increase calcium secretion

Malignant hypercalcemia

  • Paraneoplastic
  • Hypervitaminosis D

Furosemide (loop)

Reduce urine output

Diabetes insidpidus

Hydrochlorothiazide (thiazide)
Chlorothiazide (thiazide)

Urine alkalinization

Various

Carbonic anhydrase inhibitors

Meperidine (Demerol)

Meperidine is a phenylpiperidine and has a number of congeners. It is mostly effective in the CNS and bowel

  • Produces analgesia, sedation, euphoria and respiratory depression.
  • Less potent than morphine, 80-100 mg meperidine equals 10 mg morphine.
  • Shorter duration of action than morphine (2-4 hrs).
  • Meperidine has greater excitatory activity than does morphine and toxicity may lead to convulsions.
  • Meperidine appears to have some atropine-like activity.
  • Does not constrict the pupils to the same extent as morphine.
  • Does not cause as much constipation as morphine.
  • Spasmogenic effect on GI and biliary tract smooth muscle is less pronounced than that produced by morphine.
  • Not an effective antitussive agent.
  • In contrast to morphine, meperidine increases the force of oxytocin-induced contractions of the uterus.
  • Often the drug of choice during delivery due to its lack of inhibitory effect on uterine contractions and its relatively short duration of action.
  • It has serotonergic activity when combined with monoamine oxidase inhibitors, which can produce serotonin toxicity (clonus, hyperreflexia, hyperthermia, and agitation)

 

 Adverse reactions to Meperidine

• Generally resemble a combination of opiate and atropine-like effects.

- respiratory depression, - tremors, - delirium and possible convulsions, - dry mouth

• The presentation of mixed symptoms (stupor and convulsions) is quite common in addicts taking large doses of meperidine.

Oxyphenbutazone: one of the metabolites of  phenylbutazone. Apazone.  Similar to  phenylbutazone, but less likely to cause  agranulocytosis

Halothane (Fluothane) MAC 0.76%, Blood/gas solubility ratio 2.3
- Nonflammable.
- Any depth of anesthesia can be obtained in the absence of hypoxia.
- Halothane produces a marked hypotensive effect 
- accompanies hypotension.
- Halothane “sensitizes” the ventricular conduction system in the heart to the action of catecholamines. However, ventricular arrhythmias are rare if
- respiratory acidosis, hypoxia and other causes of sympathetic stimulation are avoided.
- Respiration is depressed by all anesthetic concentrations.
- Halothane is metabolized to a significant extent and some of its metabolic produces have been shown to be hepatotoxic.
- Can produce a malignant hyperpyrexia due to an uncontrolled hypermetabolic reaction in skeletal muscle. 

Halothane is generally used with nitrous oxide, an opiate and a neuromuscular blocking drug.

Ketoconazole

synthetic antifungal drug

used for infections such as  athlete's foot, ringworm, candidiasis (yeast infection or thrush), jock itch.

Ketoconazole is used to treat eumycetoma, the fungal form of mycetoma.

MOA: Ketoconazole is imidazole structured, and interferes with the fungal synthesis of  ergosterol, the main constituent of cell membranes, as well as certain enzymes. It is specific for fungi, as mammalian cell membranes contain no ergosterol.

Sensitive fungi Ketoconazole inhibits growth of  dermatophytes and  yeast species (such as Candida albicans).

Calcium Channel Blocking Agents 

• Act on contractile and conductive tissues of the heart and on vascular smooth muscles 
• Prevent movement of extracellular calcium into the cell 
– Coronary and peripheral arteries dilate
– Myocardial contractility decreases 
– Depress conduction system

Therapeutic Actions
• Inhibit movement of calcium ions across the membranes of myocardial and arterial muscle cells. Altering the action potential and blocking muscle cell contraction 
• Depress myocardial contractility 
• Slow cardiac impulse formation in the conductive tissues 
• Cause a fall in BP 
 

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