Thrombolytic Agents:

Tissue Plasminogen Activator (t-PA, Activase)

t-PA is a serine protease. It is a poor plasminogen activator in the absence of fibrin. t-PA binds to fibrin and activates bound plasminogen several hundred-fold more rapidly than it activates plasminogen in the circulation.

Streptokinase (Streptase)

Streptokinase is a protein produced by β-hemolytic streptococci. It has no intrinsic enzymatic activity, but forms a stable noncovalent 1:1 complex with plasminogen. This produces a conformational change that exposes the active site on plasminogen that cleaves a peptide bond on free plasminogen molecules to form free plasmin.

Urokinase (Abbokinase)

Urokinase is isolated from cultured human cells.Like streptokinase, it lacks fibrin specificity and therefore readily induces a systemic lytic state. Like t-PA, Urokinase is very expensive.

Contraindications to Thrombolytic Therapy:

• Surgery within 10 days, including organ biopsy, puncture of noncompressible vessels, serious trauma, cardiopulmonary resuscitation.

• Serious gastrointestinal bleeding within 3 months.

• History of hypertension (diastolic pressure >110 mm Hg).

• Active bleeding or hemorrhagic disorder.

• Previous cerebrovascular accident or active intracranial bleeding.

Aminocaproic acid:

Aminocaproic acid prevents the binding or plasminogen and plasmin to fibrin. It is a potent inhibitor for fibrinolysis and can reverse states that are associated with excessive fibrinolysis.

DOPAMINE

It is an immediate metabolic precursor of noradrenaline. It activates D1 receptors in several vascular beds, which causes vasodilatation. It acts on dopaminergic and other adrenergic receptors (α & β1).

Adverse effects of dopamine include nausea, vomiting, ectopic beats, anginal pain, tachycardia, palpitation and widened QRS.
Contraindications are atrial or ventricular tachyarrhythmias, hyperthyroidism and pheochromocytoma.

Sulfonylureas

1st generation
tolbutamide
chlorpropamide

2nd generation

glyburide
glimepiride
glipizide

Mechanism

glucose normally triggers insulin release from pancreatic β cells by increasing intracellular ATP
→ closes K+ channels → depolarization → ↑ Ca2+ influx → insulin release

sulfonylureas mimic action of glucose by closing K+ channels in pancreatic β cells 
→ depolarization → ↑ Ca2+ influx → insulin release

its use results in

↓ glucagon release
↑ insulin sensitivity in muscle and liver

Clinical use

type II DM

stimulates release of endogenous insulin 
cannot be used in type I DM due to complete lack of islet function

Toxicity

first generation

disulfiram-like effects
especially chlorpropamide

second generation

hypoglycemia
weight gain

Third Generation Cephalosporins 

Prototype drugs are CEFOTAXIME (IV) and CEFIXIME (oral). CEFTAZIDIME (for Pseudomonas aeruginosa.).

Further expansion of Gm negative spectrum to include hard to treat organisms such as Enterobacter, Serratia, and Pseudomonas. 
In addition to better Gm negative spectrum, this group has improved pharmacokinetic properties (longer half-lives) that allow once daily dosing with some agents. In general, activity toward Gm + bacteria is reduced. These are specialty antibiotics that should be reserved for specific uses. 

Enterobacteriaciae that are almost always sensitive (>95% sensitive)
E. coli
Proteus mirabilis (indole –)
Proteus vulgaris (indole +)
Klebsiella pneumoniae

Gram negative bacilli that are generally sensitive (>75% sensitive)
Morganella morganii
Providencia retgerri
Citrobacter freundii
Serratia marcescens
Pseudomonas aeruginosa (Ceftazidime only)

Gram negative bacilli that are sometimes sensitive (<75% sensitive)
Enterobacter
Stenotrophomonas (Xanthomonas) maltophilia (Cefoperazone & Ceftazidime only)
Acinetobacter

--> cefepime & cefpirome are promising for these bacteria

Bacteria that are resistant
Listeria monocytogenes
Pseudomonas cepacia
Enterococcus sp. 

Uses
1. Gram negative septicemia & other serious Gm – infections
2. Pseudomonas aeruginosa infections (Ceftazidime - 90% effective)
3. Gram negative meningitis - Cefotaxime, Ceftriaxone, Cefepime. For empiric therapy add vancomycin ± rifampin to cover resistant Strep. pneumoniae
4. Gonorrhea - Single shot of Ceftriaxone is drug of choice. Oral cefixime and ceftibuten are also OK.
5. Complicated urinary tract infections, pyelonephritis
6. Osteomyelitis - Ceftriaxone in home health care situations
7. Lyme disease - ceftriaxone in home health care situations

Classification

1. Natural Alkaloids of Opium

Phenanthrenes -> morphine, codeine, thebaine

Benzylisoquinolines -> papaverine, noscapine

2. Semi-synthetic Derivatives

diacetylmorphine (heroin) hydromorphone, oxymorphone hydrocodone, oxycodone

3. Synthetic Derivatives

phenylpiperidines pethidine, fentanyl, alfentanyl, sufentnyl

benzmorphans pentazocine, phenazocine, cyclazocine

propionanilides methadone

morphinans levorphanol

Sympathomimetics -Adrenergic Agents

The sympathomimetic or adrenergic or adrenomimetic drugs mimic the effects of adrenergic sympathetic nerve stimulation.
These are the  important group of therapeutic agents which may be used to maintain blood pressure and in certain cases of severe bronchial asthma. 

Mechanism of Action and Adrenoceptors 

The catecholamines produce their action by direct combination with receptors located on the cell membrane.  The adrenergic receptors are divided  into two main groups – alpha and beta. 
 alpha receptor - stimulation produces excitatory effect and 
 beta receptor -stimulation usually produces inhibitory effect. 
 
Alpha receptors: There are two major groups of alpha receptors, α1  and α2.
Activation of postsynaptic α1 receptors increases the intracellular concentration of calcium by activation of a phospholipase C in the cell membrane via G protein. 
α2 receptor is responsible for inhibition of renin release from the kidney and for central aadrenergically mediated blood pressure depression.

Beta  receptors: 

a. Beta 1  receptors have approximately equal affinity for adrenaline and noradrenaline and are responsible for myocardial stimulation and renin release.

b. Beta 2 -  receptors have a higher affinity for adrenaline than for noradrenaline and are responsible for bronchial muscle relaxation, skeletal muscle vasodilatation and uterine relaxation.

c. Dopamine receptors: The D1 receptor is typically associated with the stimulation of adenylyl cyclase. The important agonist of dopamine receptors is fenoldopam (D1) and bromocriptine (D2) and antagonist is clozapine (D4) .

Adrenergic drugs can also be classified into:

a. Direct sympathomimetics: These act directly on a or/and b adrenoceptors e.g. adrenaline, noradrenaline, isoprenaline, phenylephrine, methoxamine salbutamol etc.
b. Indirect sympathomimetics: They act on adrenergic neurones to release noradrenaline e.g. tyramine.
c. Mixed action sympathomimetics: They act directly as well as indirectly e.g. ephedrine, amphetamine, mephentermine etc.

Pharmacological Action of Sympathomimetics 

Heart: Direct effects on the heart are determined largely by β1 receptors.
Adrenaline increases the heart rate, force of myocardial contraction and cardiac output

Blood vessels: Adrenaline and noradrenaline constrict the blood vessels of skin and mucous membranes. 
 Adrenaline also dilates the blood vessels of the skeletal muscles on account of the preponderance of  β2 receptor 
 
Blood pressure: Because of vasoconstriction (α1) and vasodilatation (β2) action of adrenaline, the net result is decrease in total peripheral resistance.

Noradrenaline causes rise in systolic, diastolic and mean blood pressure and does not cause vasodilatation (because of no action on β2  receptors) and increase in peripheral resistance due to its a action.

Isoprenaline causes rise in systolic blood pressure (because of β1 cardiac stimulant action) but marked fall in diastolic blood pressure (because of b2 vasodilatation action) but mean blood pressure generally falls.

GIT: Adrenaline causes relaxation of smooth muscles of GIT and reduce its motility. 

Respiratory system: The presence of β2 receptors in bronchial smooth muscle causes relaxation and activation of these receptors by β2 agonists cause bronchodilatation.
Uterus: The response of the uterus to the atecholamines varies according to species

Eye: Mydriasis occur due to contraction of radial muscles of iris, intraocular tension is lowered due to less production of the aqueous humor secondary to vasoconstriction and conjunctival ischemia due to constriction of conjunctival blood vessels.

a. Urinary bladder: Detrusor is relaxed (b) and trigone is constricted (a) and both the actions tend to inhibit
micturition. 

b. Spleen: In animals, it causes contraction (due to its a action) of the splenic capsule resulting in increase in number of RBCs in circulation.

c. It also cause contraction of retractor penis, seminal vesicles and vas deferens.

d. Adrenaline causes lacrimation and salivary glands are stimulated. 

e. Adrenaline increases the blood sugar level by enhancing hepatic glycogenolysis and also by decreasing the uptake of glucose by peripheral tissues.
Adrenaline inhibits insulin release by its a-receptor stimulant action whereas it stimulates glycogenolysis by its b receptor stimulant action.

f. Adrenaline produces leucocytosis and eosinopenia and accelerates blood coagulation and also stimulates platelet aggregation.

Adverse Effects

Restlessness, anxiety, tremor, headache.
Both adrenaline and noradrenaline cause sudden increase in blood pressure, precipitating sub-arachnoid haemorrhage and occasionally hemiplegia, and ventricular  arrhythmias. 
May produce anginal pain in patients with ischemic heart disease. 

Contraindications

a. In patients with hyperthyroidism.
b. Hypertension.
c. During anaesthesia with halothane and cyclopropane.
d. In angina pectoris.

Therapeutic Uses

Allergic reaction: Adrenaline is drug of choice in the treatment of various acute allergic disorders by acting as a physiological antagonist of histamine (a known mediator of many hypersensitivity reactions). It is used in bronchial asthma, acute angioneurotic edema, acute hypersensitivity reaction to drugs and in the treatment of anaphylactic shock.

Bronchial asthma: When given subcutaneously or by inhalation, adrenaline is a potent drug in the treatment of status asthmaticus.

Cardiac uses: Adrenaline may be used to stimulate the heart in cardiac arrest.
Adrenaline can also be used in Stokes-Adam syndrome, which is a cardiac arrest occurring at the transition of partial to complete heart block. Isoprenaline or orciprenaline may be used for the temporary treatment of partial or complete AV block.

Miscellaneous uses:

a. Phenylephrine is used in fundus examination as mydriatic agent.
b. Amphetamines are sometime used as adjuvant and to counteract sedation caused by antiepileptics.
c. Anoretic drugs can help the obese people.
d. Amphetamine may be useful in nocturnal enuresis in children.
e. Isoxsuprine (uterine relaxant) has been used in threatened abortion and dysmenorrhoea.