pharma notes

1. Prototype drugs and other important drugs of the groups
(Only main differentiating features of these drugs;
All other features are similar to prototype drug)
Autonomic Nervous System
CHOLINOMIMETICS (Acetylcholine)
Mechanism of Action: Activate Muscarinic Receptors M1 , M2 , M3
Clinical Uses:
Uses in Eye:
1. Glaucoma: Acute angle-closure glaucoma, Chronic open-angle
glaucoma, Secondary glaucoma due to trauma, surgery or
inflammatory drugs.
2. Esotropia: strabismus / squint due to hypermetropia
3. Posterior or Anterior Synechae.
Uses in GIT:
1. Post-operative Paralytic ileus.
2. Reflux esophagitis
3. Congenital Megacolon.
4. Gastric atony / stasis.
5. Sjogren syndrome (xerostomia with disorder like SLE, Rh. Arthritis
etc.).
Other uses:
1. Neurogenic Bladder
2. Myasthenia Gravis
3. Antimuscarinic intoxication
4. Supraventricular Tachyarrhythmia's
Contraindications:
1. Mechanical Obstruction of GIT & Urinary Bladder.
2. Bronchial asthma,
3. Peptic ulcer,
4. Cardiac Arrhythmias -hyperthyroidism.
Pilocarpine
Mechanism of Action: Activate non-selectively M receptors
Uses:
Topically useful
1. Emergency lowering of narrow & wide- angle glaucoma.
2. Xerostomia.
Carbachol (ACh like effects)

2. Mechanism of Action: Activate both on M & N receptors
Uses:
 Topically for Glaucoma,
 Systemically: Urinary retention, Paralytic Ileus, Raynaud’s Disease.
Bethanechol
Mechanism of Action: Activate non-selectively M receptors
Uses: Bladder and Bowel Atony, e.g. after Surgery and Spinal Cord Injury
Edrophonium
Mechanism of Action:
Inhibitor of the enzyme, cholinesterase, very short acting, so amplifier of
endogenously released ACh for about 10 min. only
Uses:
1. Diagnosis of Myasthenia Gravis,
2. Lambert – Eaten Syndrome.
Adverse Effects: Insomnia, Seizures
Neostigmine
Mechanism of Action:
Inhibitor of the enzyme, cholinesterase so amplifier of endogenously
released ACh; Some direct agonistic actions at NN also.
Uses:
(Can’t cross the blood brain barrier so mainly used in peripheral
conditions)
1. Myasthenia Gravis,
2. Post-operative Paralytic ileus.
3. Gastric atony / stasis.
4. Bladder and Bowel Atony, e.g. After Surgery and Spinal Cord Injury
5. Urinary Retention
Contraindications:
 Increased Tone of Parasympathetic Nervous System, like increased
Motility Function of Stomach or Intestines, Bradycardia, Asthma,
Urinary Tract Blockage, Seizures, Overactive Thyroid Gland
Drug Interactions:
With drugs having antinicotinic &/or antimuscarinc effects
 Aminoglycoside antibiotics (e.g., gentamicin)... opposite (antinicotinic)
effects;
 Antimuscarinc effects with antiarrhythmic drugs (e.g., quinidine),
drugs that decrease the movements of the stomach (e.g.,
antihistamines such as diphenhydramine, antispasmodics such as
dicyclomine, narcotic pain medications such as morphine).
Physostigmine
Mechanism of Action:

3. Inhibitor of cholinesterase, amplifier of endogenously released ACh
Uses:
(Can cross the blood barrier, so mainly used in central conditions)
1. Reversal of severe Atropine poisoning,
2. Acute Glaucoma
Drug Interactions:
 Cholinergic agonists (e.g., pilocarpine),
 Quinine derivatives (which have antagonistic effects at NN so may
reverse the beneficial effects of physostigmine in the treatment of
myasthenia gravis; avoid concurrent use.)
 Valproic acid
Contraindications:
 Parkinson Symptoms, Epileptic Seizure, Slow Heartbeat, Disease of the
Heart and Blood Vessels, Asthma, Urinary Tract Blockage, Diabetes
Echothiophate: Not used now (obsolete); but was useful in glaucoma.
Pralidoxime:
Mechanism of Action:
Enzyme cholinesterase re-activator,
So used as chemical antagonist of organophosphates
Uses: Organophosphate poisoning
Adverse Effects: Muscle weakness
Succinylcholine:
Mechanism of Action: Moderately selective for neuromuscular (NM) end
plate
Uses: NM relaxation
Toxicity: Initial muscle spasms and postoperative pain; prolonged action
with genetically abnormal butyrylcholinesterase.
ANTIMUSCARINICS
Atropine:
Mechanism of Action:
Block M1 M2 M3 etc. (So unopposed adrenergic receptors dominate)
Therapeutic Uses
 Pre-anaesthetic Medication
 Peptic ulcer
 To check excessive sweating or salivation, as in parkinsonism,
 Colicky Pain in intestinal / renal colic;

4.  Diarrhea in nervous, functional, drug-induced, Irritable Bowel
Syndrome or Colonic Diverticular Disease;
 Pylorospasm with Gastritis / Nervous Dyspepsia:
 Genitourinary disorders: e.g., cystitis, urethritis, prostitis, enuresis in
children: with increased frequency & urgency;
 Asthma with COPD / Bronchitis:
 Diagnostic Uses for testing error of refraction, fundoscopy,
 Therapeutic Uses in iritis, iridocyllitis, chorioditis, keratitis, corneal
ulcers, anterior / post. synechae
 Other Uses like in Myocardial Infarction, Digitalis Toxicity, Sinus
bradycardia – Hypersensitive vagus nerve, Antidote for Mushroom
Poisoning, Snake Bite, and Curare Effects.
Side Effects & Toxicity:
 Dry mouth, difficulty in talking, chewing / swallowing
 Dry, flushed & hot skin esp. over face & neck, fever, scarlet rash.
 Dilated pupil, photophobia, blurring of near vision, aggravation of
glaucoma.
 Excitement, psychotic behaviour, ataxia, delirium, hallucinations,
convulsions, coma.
 Palpitations, weak & rapid pulse, hypotension, circulatory collapse.
 Urinary bladder: Difficulty in micturation, urinary retention
 GIT: Constipation, aggravation of gastric ulcer due to delayed
emptying.
Contra-indications:
 Glaucoma: narrow angle: precipitation of acute congestive glaucoma.
 Prostate Hypertrophy: in elderly
 Peptic Ulcer: with care.
 Young Infants: with high grade fever: convulsions may occur.
Drug Interactions:
 Additive Effects with Antihistamines, Phenothiazines, Tricyclic
antidepressants, Disopyramide, Meperidine (Pethidine).
 Altered Absorption of Levodopa: slower absorption-delayed emptying
so rapid GIT metabolism. Digoxin / Tetracyclines: Increased
absorption (longer transit time). Antacids: Decreased absorption of
anti-cholinergics.
 Altered Metabolism of MAO inhibitors: Decreased metabolism by anti-
cholinergics so increased concentrations ------ Delirium.
Scopolamine:
Mechanism of action: Competitive antagonist at all M receptors
Uses:
1. Motion Sickness

5. 2. Intestinal cramping
3. Anti-emetic
Adverse Effects:
Constipation, tachycardia, difficulty in urinating, thirst, delirium,
hallucination, blurred vision
Contraindications:
Closed Angle Glaucoma, High Blood Pressure, Urinary Tract Blockage,
Enlarged Prostate, Down syndrome, Drowsiness
Drug Interactions: with morphine to produce amnesia and twilight
sleep.
Ipratropium:
Mechanism of Action:
Competitively all M blocker, esp. on the bronchial smooth muscle
Therapeutic uses:
1. Prevention and relief of acute episodes of bronchospasm
2. Treatment of asthma
3. Chronic Bronchitis
Adverse effects:
 Dryness of mouth
 Cough
Drug Interactions: Antimuscarinic drugs.
Pirenzepine:
Mechanism of Action: Significant M1 selectivity
Uses: Peptic disease
ADRENOCEPTOR AGONISTS
Epinephrine:
Mode of Action: dose dependent affects on all α and β receptors.
Therapeutic Uses:
1. Anaphylactic shock
2. Prolongs duration of local anaesthetic effect
3. Acute attack of bronchial asthma
Adverse Affects:
 Arrhythmias – may be fatal ventricular arrhythmias.
 Hypertension, stroke.
 Precipitation of ischemic heart diseases, even myocardial infarction.
 Pulmonary edema
 Palpitations, Anxiety
 Headaches

6. Contraindications:
 H/O
Ischemic Heart Disease
Hypertension
Arrhythmias
 Sinus tachycardia
 Closed angle glaucoma
 Hyperthyroidism
Norepinephrine:
Mode of Action: Affects on α1-2 receptors and β1 receptors
Therapeutic Uses: Neurogenic shock; last resort therapy in shock
Adverse Affects:
 Extreme vasospasm, tissue necrosis;
 Excessive blood pressure increase,
 Arrhythmias,
 Myocardial infarction
Contraindications:
 Patients with H/O Ischemic Heart Disease, Hypertension, Arrhythmias
 Hyperthyroidism
Dopamine:
Mechanism of action: Dopamine acts on D1 receptors, all α and β
receptors
Actions:
 Cardiovascular: causes vasoconstriction
 Renal and Visceral: increases blood flow to kidneys and other viscera
Therapeutic uses:
 Cardiogenic, Septic shock / esp. With renal shutdown,
 Sometimes to treat hypotension and severe congestive heart failure
Adverse effects:
 Nausea
 Cardiovascular disturbance
 Arrhythmias
 Hypertension
Dobutamine:
Mechanism of Action: Acts on β1 receptors
Uses: Acute Heart Failure
Phenylephrine:
Mechanism of Action: Acts on mainly on α1 receptors (alpha2 also)
Uses:
 Nasal decongestant

7.  Mydriatic
 Neurogenic hypotension
Adverse Effects
 Hypertension
 Stroke
 Myocardial infarction
Albuterol (Salbutamol – Ventolin):
Mode of Action: β2 agonist
Uses: Asthma
Adverse Effects
 Tremor
 Tachycardia
Fenoldopam:
Mode of Action: D1 Agonists: Vascular smooth muscle relaxation
Uses: (iv use for) Severe Hypertension & Postoperative hypertension
Adverse Effects
 Reflex tachycardia,
 headache, and
 flushing
Contraindication: Glaucoma, as it increases intraocular pressure
Amphetamine
Mechanism of Action:
It is an indirect-acting adrenergic agonist, causes displacement of
catecholamine neurotransmitters esp. NE from the neuronal stores and
thus elevation of their levels in the synaptic spaces.
Actions:
 It stimulates the entire CNS esp. stimulates the sympathetic nervous
system.
Therapeutic Uses
 As anorexiant
 For Attention Deficit Hyperactivity Disorder (ADHD).
 To improve wakefulness in narcolepsy.
Adverse Effects
 High addiction liability
 Paranoia,
 Aggression;
 Insomnia
 cardiovascular effects: palpitations, cardiac arrhythmias, hypertension,
angina pain and circulatory collapse
 Its causes anorexia, nausea, vomiting, abdominal cramps and diarrhea

8. Contraindications
 Patients suffering from hypertension.
 Cardiovascular diseases.
 Hyperthyroidism.
 Glaucoma.
 Patients taking MAO inhibitors.
ADRENERGIC RECEPTOR BLOCKERS
Prazosin:
Mode of Action: Competitively blocks α1 adrenoceptors.
Uses:
1. Hypertension; Pheochromocytoma
2. Benign prostatic hyperplasia
3. Severe congestive heart failure
Adverse Effects:
 First dose effect: Syncope
 Orthostatic hypotension
 Nasal congestion
 Priapism
Phenoxybenzamine:
Mode of Action:
Irreversibly blocks α1 and α2; blocks α-mediated vasoconstriction, lowers
BP, increases heart rate reflexly.
Uses: Pheochromocytoma / High catecholamine states
Adverse Effects:
 Orthostatic Hypotension
 Reflex Tachycardia
 Myocardial ischemia (reflex cardiac stimulation; increased cardiac work
load)
Tamsulosin:
Mode of Action:
Slightly selective α1A blocker; may relax prostatic smooth muscles more
than vascular smooth muscle
Uses: Benign prostatic hyperplasia
Adverse Effects: Less orthostatic Hypotension or reflex cardiac
stimulation
Yohimbine:
Mode of Action:

9. Competitively blocks α2; elicits increased central sympathetic activity;
increased norepinephrine release
Uses:
 For Research Purpose (Obsolete use for male erectile dysfunction)
 Hypotension
Adverse Effects:
 May cause anxiety
 Excess pressor effect if norepinephrine transporter is blocked.
 GIT upset
Propranolol:
Mode of Action: Non-selective β1, β2 blocker
Uses:
1. Hypertension
2. Ischemic heart diseases: angina pectoris, myocardial infarction
3. Arrhythmias- atrial arrhythmias and prevention of infarction and
sudden death
4. Prophylaxis of migraine
5. Hyperthyroidism
6. Performance anxiety / stage fright - essential tremors
7. Glaucoma
Adverse Effects:
 Bronchospasm (can be fatal in
asthmatics),
 Atrioventricular block,
 Heart failure;
 CNS sedation,
 Lethargy
 Sleep disturbances
 Fatigue
 Vivid dreams
 Cold hands
 Depression
 Decreased sex drive
Contraindications:
 Bronchial asthma
 Bradycardia
 Atrioventricular block
 Peripheral vascular disease
Drug Interactions:
 Epinephrine
 Salbutamol
 Theophylline
 Diltiazem
 Verapamil
 Disopyramide
 Lidocaine
 Methyldopa
 Terazosin
 Topotecan
Timolol / betaxolol:
Mode of Action: Non-selective β1, β2 blocker
Uses: Useful in glaucoma
Metoprolol/Atenolol, etc.
Mode of Action: Selective β1 blockers

10. Uses: All cardio-selective uses but safer in asthma
ADRENERGIC NEURON BLOCKERS
Reserpine:
Mode of Action: Blocks vesicular amine transporter in noradrenergic
nerves and depletes transmitter stores.
Uses:
1. Occasionally in hypertension
2. Huntington's disease
Adverse Effects:
 Psychiatric depression (high doses), sedation, lassitude, and
nightmares
 Gastrointestinal disturbances: mild diarrhea, abdominal cramps and
increases gastric acid secretion.
Contraindications: Peptic ulcer.
Guanethidine
Mode of Action: Guanethidine acts at the postganglionic sympathetic
nerve terminal and depletes the neurotransmitter stores
(norepinephrine); it also blocks the reuptake of norepinephrine
Uses: Obsolete in many countries; moderate to severe hypertension
Adverse Effects:
 Symptomatic postural hypotension
 Hypotension following exercise, particularly with high doses.
 Delayed or retrograde ejaculation (into the bladder)
 Diarrhea (increased gastrointestinal motility).
Contraindications:
 Patients with Pheochromocytoma
 Congestive heart failure
 Narrow-angle glaucoma
 Hypersensitivity
Drug Interactions:
 Sympathomimetic agents, in the cold preparations.
 Tricyclic antidepressants(severe hypertension)