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Pharmacology - NEETMDS- courses
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Pharmacology

Propoxyphene

  • A methadone analog.Used orally to relieve mild to moderate pain.
  • A typical opiate, it does not possess anti-inflammatory or antipyretic actions, but has little or no antitussive activity.
  • Cannot be used parenterally because of irritant properties.
  • Has a low addiction potential primarily due to its lack of potency as an opiate.
  • The most common adverse side effects are:• dizziness, drowsiness, and nausea and vomiting. • these effects are more prominent in ambulatory patients.
  • Withdrawal symptoms have occurred in both adults and in neonates following use of the drug by the mother during pregnancy.
  • CNS depression is additive with other CNS depressants.

Miconazole

Miconazole is an  imidazole antifungal agent commonly used in topical sprays, creams and ointments applied to the  skin to cure fungal infections such as Athlete's foot and Jock itch. It may also be used internally to treat vaginal  yeast infection.

When used by a person taking the anticoagulant medication warfarin, Miconazole may cause an adverse reaction which can lead to excessive bleeding or bruising.

Carbapenems: Broadest spectrum of beta-lactam antibiotics.

imipenem with cilastatin

meropenem

ertapenem

Monobactams: Unlike other beta-lactams, there is no fused ring attached to beta-lactam nucleus. Thus, there is less probability of cross-sensitivity reactions.

aztreonam

Beta-lactamase Inhibitors No antimicrobial activity. Their sole purpose is to prevent the inactivation of beta-lactam antibiotics by beta-lactamases, and as such, they are co-administered with beta-lactam antibiotics.

clavulanic acid

tazobactam

sulbactam

Barbiturates (BARBS): 

were used for antianxiety, sedation but now replaced by BZs; for IV sedation & oral surgery

Advantages: effective and relatively inexpensive (common in third world countries), extensively studied so have lots of information about side effects/toxicity

Peripheral effects: respiratory depression (with ↑ dose), CV effects (↓ BP and HR at sedative-hypnotic doses), liver effects (bind CYP450 → induction of drug metabolism and other enzymes → ↑ metabolism of steroids, vitamins K/D, cholesterol, and bile salts)

General mechanisms: potently depress neuron activity in the reticular formation (pons, medulla) and cortex 
o    Bind barbiturate site on GABAA receptor → enhanced inhibitory effect and ↑ Cl influx; → ↓ frequency of Cl channel opening but ↑ open time of Cl channels (in presense of GABA) so more Cl enters channel (at high [ ] they directly ↑ Cl conductance in absence of GABA- act as GABA mimetics)

Metabolism: liver microsomal drug metabolizing enzymes; most are dealkylated, conjugated by glucoronidation; renal excretion

Uses: anticonvulsant, preoperative sedation, anesthesia

Side effects: sedation, confusion, weight gain, N/V, skin rash

Contraindications: pain (can ↑ sensitivity to painful situations → restlessness, excitement, and delirium) and pulmonary insufficiency (since BARBS → respiratory depression)

Drug interactions: have additive depressant affects when taken with other CNS depressants, enhance depressive effects (of antipsychotics, antihistamines, antiHTNs, ethanol, and TCAs), and accelerates metabolism (of β blockers, Ca-channel blockers, corticosteroids, estrogens, phenothiazines, valproic acid, and theophylline; occurs with chronic BARB ingestion)

Acute toxicity: lower therapeutic index; can be fatal if OD; BARB poisoning a major problem (serious toxicity at only 10x hypnotic dose; → respiratory depression, circulatory collapse, renal failure, pulmonary complications which can be life-threatening)

Symptoms: severe respiratory depression, coma, severe hypotension, hypothermia

Treatment: support respiration and BP, gastric lavage (if recent ingestion)

Tolerance: metabolic (induce hepatic metabolic enzymes, occurs within a few days), pharmacodynamic (↓ CNS response with chronic exposure occurs over several weeks; unknown mechanism), and cross tolerance (tolerance to other general CNS depressants)

Physical dependence: develops with continued use; manifest by withdrawal symptoms (mild = anxiety, insomnia, dizziness, nausea; severe = vomiting, hyperthermia, tremors, delirium, convulsions, death)

Other similar agents: meprobamate (Equanil; pharmacological properties like BZs and barbiturates but mechanism unknown) and chloral hydrate (common sedative in pediatric dentistry for diagnostic imaging; few adverse effects but low therapeutic index)

Other drugs for antianxiety: β-adrenoceptor blockers (e.g., propranolol; block autonomic effects- palpitations, sweating, shaking; used for disabling situational anxiety like stage fright), buspirone (partial agonist at serotonin 1A receptor, produces only anxiolytic effects so no CNS depression, dependence, or additive depression with ethanol but onset of action is 1-3 weeks), lodipem (not a BZ but does act at BZ receptors)

BradyKinin

An endogenous vasodilator occurring in blood vessel walls. 
At least two distinct receptor types, B1 and B2, appear to exist for BradyKinin

Roles of bradykinin:

1) Mediator of inflammation and pain.
2) Regulation of microcirculation.
3) Their production is interrelated with clotting and fibrinolysin systems.
4) Responsible for circulatory change after birth.
5) Involved in shock and some immune reactions.

Class IV Calcium Channel Blockers
• Block the movement of calcium into conductile and contractile myocardial cells 
• Treatment: treatment of supraventricular tachycardia 
– Diltiazem 
– Verapamil 

Adverse Effects 
• Adverse effects associated with vasodilation of blood vessels throughout the body. 
• CNS – dizziness, weakness, fatigue, depression and headache, 
• GI upset, nausea, and vomiting. 
• Hypotension CHF, shock arrhythmias, and edema 
 

OXYMETAZOLINE
 

It is a directly acting sympathomimetic amine used in symptomatic relief in nasal congestion which increases mucosal secretion.

It is used:
- As a nasal decongestant in allergic rhinitis, with or without the addition of antazoline or sodium chromoglycate. 
- As an ocular decongestant in allergic conjunctivitis.

Compounds like naphazoline and xylometazoline are relatively selective α2 agonists, which on topical application produce local vasoconstriction.

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