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 
 

Antiplatelet Drugs:

Whereas the anticoagulant drugs such as Warfarin and Heparin suppress the synthesis or activity of the clotting factors and are used to control venous thromboembolic disorders, the antithrombotic drugs suppress platelet function and are used primarily for arterial thrombotic disease. Platelet plugs form the bulk of arterial thrombi.

Acetylsalicylic acid (Aspirin)

• Inhibits release of ADP by platelets and their aggregation by acetylating the enzymes (cyclooxygenases or COX) of the platelet that synthesize the precursors of Thromboxane A2 that is a labile inducer of platelet aggregation and a potent vasoconstrictor.

• Low dose (160-320 mg) may be more effective in inhibiting Thromboxane A2 than PGI2 which has the opposite effect and is synthesized by the endothelium.

• The effect of aspirin is irreversible.

Inhalational Anesthetics

The depth of general anesthesia is directly proportional to the partial pressure of the anesthetic agent in the brain. These agents enter the body through the lungs, dissolve in alveolar blood and are transported to the brain and other tissues.

A. Rate of induction and rate of recovery from anesthesia:

1. The more soluble the agent is in blood, the more drug it takes to saturate the blood and the more time it takes to raise the partial pressure and the depth of anesthesia.

2. The less soluble the agent is in blood, the less drug it takes to saturate the blood and the less time it takes to raise the partial pressure and depth of anesthesia.

B. MAC (minimum alveolar concentration)

The MAC is the concentration of the anesthetic agent that represents the ED₅₀ for these agents. It is the alveolar concentration in which 50% of the patients will respond to a surgical incision.

The lower the MAC the more potent the general anesthetic agent.

C. Inhalation Anesthetic Agents 

• Nitrous Oxide
• Ether
• Halothane
• Enflurane
• Isoflurane

Warfarin (Coumadin):

• The most common oral anticoagulant.
• It is only active in vivo.
• Warfarin is almost completely bound to plasma proteins. -96% to 98% bound.
• Warfarin is metabolized by the liver and excreted in the urine.
• Coumarin anticoagulants pass the placental barrier and are secreted into the maternal milk.
• Newborn infants are more sensitive to oral anticoagulants than are adults because of lower vitamin K levels and lower rates of metabolism.

• Bleeding is the most common side effect and occurs most often from the mucous membranes of the gastrointestinal tract and the genitourinary tract.

Oral anticoagulants are contraindicated in:

• Conditions where active bleeding must be avoided, Vitamin K deficiency and severe

hepatic or renal disease, and where intensive salicylate therapy is required.

NSAIDs: Classification by Plasma Elimination Half Lives

Short Half Life (< 6 hours):

more rapid effect and clearance

• Aspirin (0.25-0.33 hrs),

• Diclofenac (1.1 ± 0.2 hrs)

• Ketoprofen (1.8± 0.4 hrs),

• Ibuprofen (2.1 ± 0.3 hrs)

• Indomethacin (4.6 ± 0.7 hrs)

Long Half Life (> 10 hours):

slower onset of effect and slower clearance

• Naproxen (14 ± 2 hrs)

• Sulindac (14 ± 8 hrs),

• Piroxicam (57 ± 22 hrs)

Lithium carbonate: 1st choice (controls mania in bipolar disorders); delay before onset of therapeutic benefit; no psychotropic effects in normal humans

i. Mechanism: blocks enzymes in inositol phosphate signaling pathway; no consistent effects of lithium on NE, 5-HT, and DA
ii. Side effects: severe CNS (ataxia, delirium, coma, convulsions) and CV (cardiac dysrhythmias)