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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5282_Библиотеки_им_академика_М_И_Перельмана
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55
Inorganic Pharmaceuticals
Pharmaceutical Form
Liquid oxygen (Purity 99.5% v/v minimum)
Medicinal gas
Medical uses of Oxygen
To provide a basis for modern anesthetic techniques.
To restore tissue oxygen tension by improving oxygen availability in chronic conditions
such as COPD (Chronic Obstructive Pulmonary Disease), cyanosis, shock, severe
hemorrhage, carbon monoxide poisoning, major trauma, cardiac/respiratory arrest, etc.
Aid resuscitation.
In artificial ventilator.
To aid cardiovascular stability.
In surgical trauma, chest wounds and rib fracture.
In coronary occlusion.
In hyperpyrexia.
Contraindications
Should be controlled in case of premature infants, in COPD and emphysema patients.
Side Effects
Retro lenticular fibroplasia in premature infants exposed to oxygen concentrations greater
than 40%.
Chances of convulsions after a few hours exposure to medical oxygen at pressures above
3 bar (g).
Storage Condition
Store undercover, preferably inside, keep dry and clean, and not subjected to extremes of
heat or cold.
Keep away from stocks of combustible material.
Store separately from industrial and other non-medical gas cylinders.
Color Coding
The whole cylinder has white color.
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A Textbook of Pharmaceutical
Chemistry
Shelf Life
6 months
Medical Carbon Dioxide
Pharmaceutical Form
Liquid carbon dioxide (Purity 99.5 % v/v minimum)
Medical uses of Carbon Dioxide
To increase the depth of anesthesia rapidly when volatile agents are being administered.
To increase cerebral blood flow in arteriosclerotic patients who underwent surgery.
To stimulate respiration after a period of apnea (loss of breathing).
In chronic respiratory obstruction.
To prevent hypo apnea during hyperventilation.
For clinical and physiological investigations.
Contraindications
In acidosis
In respiratory obstruction
The use of carbon dioxide is not recommended in pregnancy.
Side Effects
Unconsciousness in concentrations over 10%.
Cardiac dysrhythmias have been reported in patients of laproscopy as a result of high
blood carbon dioxide levels.
Storage Condition
Store undercover, preferably inside, keep dry and clean, and not subjected to extremes of
heat or cold.
Keep away from stocks of combustible material.
Store separately from industrial and other non-medical gas cylinders.
Color Coding
The shoulder of the cylinder is grey in color.
The body of the cylinder is white in color.
57
Inorganic Pharmaceuticals
Shelf Life
36 months
Medical Nitrous Oxide
Pharmaceutical Form
Compressed nitrous oxide gas (Purity 98.0 % v/v minimum)
Medical uses of Nitrous Oxide
Simultaneous administration with volatile agents such as halothane, etc.
In the relief of severe pain, usually in emergencies, by inhalation with 50% oxygen.
In dental work to provide short-term analgesia for tooth extraction and other brief
procedures, administered with 50% oxygen.
Occasionally as an insufflating agent in laproscopy.
In cryosurgery as a refrigerant.
Contraindications
Nitrous oxide should not be used with any condition such as:
Head injuries
Artificial, traumatic, or spontaneous pneumothorax (abnormal collection of air in the
pleural space that causes an uncoupling of the lung from the chest wall)
Air embolism
Decompression sickness
Following a recent underwater dive
Following air encephalography
Severe bullous emphysema (shortness of breath due to over-inflation of the alveoli)
During myringoplasty (closure of the perforations of the ear drum)
Side Effects
Euphoria
Disorientation
Sedation
Nausea
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A Textbook of Pharmaceutical
Chemistry
Vomiting
Dizziness
Storage Condition
Store undercover, preferably inside, keep dry, and clean and not subjected to extremes of
heat or cold.
Keep away from stocks of combustible material.
Store separately from industrial and other non-medical gas cylinders.
Color Coding
The shoulder of the cylinder is blue in color.
The body of the cylinder is white in color.
Note: From the year 2025 whole cylinder would be blue in color.
Shelf Life
36 months.
General Information
59
Chapter
Drugs Acting on
Central Nervous
System (CNS)
The central nervous system consists of the brain and spinal cord. The CNS controls most of
the functions of the body and mind. The drugs acting on CNS are classified based on their use.
This category includes the drugs that exert their action by acting on the central nervous
system.
7.1 GENERAL ANESTHETICS (GA)
A general anesthetic is a class of CNS depressant drugs that produce reversible partial or
total loss of consciousness.
Stages of Anesthesia
Guedel divided anesthesia into four different stages in 1937.
Stage-I Analgesia
Consciousness is maintained, analgesia is produced. Since higher cortical centers are
depressed, this stage is also called as a cortical stage.
Stage-II Delirium
In this stage removal of cortical inhibition leads to excitement and the patient may shout and
struggle violently. This stage is also called as a stage of excitement.
Stage-III Surgical Anesthesia
Skeletal muscles are relaxed and most of the operative procedures are performed at this stage.
Stage-IV Respiratory Paralysis
This is a toxic stage in which there is respiratory and cardiovascular collapse.
7
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A Textbook of Pharmaceutical
Chemistry
Meyer-Overton Theory of Anesthesia
The Meyer-Overton theory describes the correlation between lipid solubility of inhaled
anesthetics and MAC (Minimum Alveolar Concentration) and suggests that anesthesia occurs
when a sufficient number of inhalational anesthetic molecules dissolve in the lipid cell membrane.
GA are classified as follows:
(a) Inhalational anesthetics
(i) Volatile liquids
Ether
Halothane
Isoflurane
(ii) Gaseous
Nitrous oxide
(b) Intravenous anesthetics
(i) Fast-acting drugs
Thiopental sodium
Propofol
Etomidate
(ii) Slower acting drugs
Opioid analgesic – Fentanyl
(c) Dissociative anesthetic
Ketamine
Thiopental Sodium
Structure:
HN N
O
S
O
Na
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Drugs Acting on Central Nervous System (CNS)
Chemical name: (RS)-[5-Ethyl-4, 6-dioxo-5-(pentan-2-yl)-1, 4,5,6-tetrahydropyrimidine-2-
yl]-sulfanide sodium.
Use: As a ageneral anesthetics.
Formulation: Single dose injection i.e., Ampoule.
Brand names: PENTOTHAL, INTRAVAL SODIUM.
Ketamine
Structure:
Cl
NH
O
Chemical name: (RS)-2-(2-Chlorophenyl)-2-(methylamino)-cyclohexanone.
Use: As a general anesthetic.
Formulation: Single dose injection i.e., Ampoule.
Brand names: KETALAR, KETMIN, KETAMAX.
7.2 LOCAL ANESTHETICS (LA)
Local anesthetics are the agents which cause the reversible absence of pain sensation of the
selective part of the body. They are applied to achieve selective analgesia of a restricted part of
the body or local area of the body. These drugs are mainly useful for the temporary relief of
localized pain and itching due to minor burns, insect bites, allergic reactions, dental surgery,
minor surgeries, etc.
LA’s are used in different ways:
(a) Topical anesthesia: It is used to relieve pain or itching at mucous surfaces and wounds.
It is not directly applied to the broken skin.
(b) Nerve block: A relatively higher concentration of drugs is injected as close as possible to
the main nerve trunk supplied.
(c) Spinal anesthesia: A drug is injected into the subarachnoid space (spinal cord) to block
the roots of nerves.
(d) Infiltration anesthesia: In which drug is injected at one or more sites in and around the
area.
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A Textbook of Pharmaceutical
Chemistry
LA’s are classified as:
(a) Injectable anesthetics
(i) Low potency anesthetics:
Procaine
(ii) Intermediate potency anesthetics:
Lidocaine, Prilocaine
(iii) High potency anesthetics:
Tetracaine, Bupivacaine
(b) Surface anesthetics
(i) Soluble anesthetics:
Lidocaine
Tetracaine
(ii) Insoluble anesthetics:
Benzocaine
Approved New Drugs
Dexmedetomidine
Mechanism of action: It has a specific and selective alpha-2 adrenoceptor agonist activity. It
is a new, short-acting, ester-based anesthetic agent.
Remimazolam
Mechanism of action: It specifically binds to benzodiazepine receptors in the brain with
high affinity. It does not show any affinity for other receptors, resulting in lower side effects.
7.3 SEDATIVES AND HYPNOTICS
Sedatives are agent that induces sedation and serves to calm or relieve anxiety. On the other
hand, hypnotics (Greek Hypnos – sleep) induce sleep. These actions are dose-dependent which
means in smaller doses the agents act as a sedative and in higher doses act as hypnotic. Hypnotics
induce sleep that is similar in sleep pattern to natural sleep. A sedative drug decreases the activity
and excitement of the patient and calms the anxiety by producing mild depression of CNS without
causing sleep. A hypnotic drug produces drowsiness by depressing the CNS.
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Drugs Acting on Central Nervous System (CNS)
Various sedative-hypnotic agents are employed as:
Antianxiety agents
Anticonvulsant agents
Muscle relaxants
General anesthetics
The prolonged administration of these agents is not recommended because it may result into:
Alteration of natural sleep.
Chances of tolerance and physical dependence on the drug.
Hangover effect.
They are classified as follows:
(a) Benzodiazepines
(i) Hypnotic drugs
Diazepam
Flurazepam
Nitrazepam
Alprazolam
(ii) Antianxiety drugs
Diazepam
Oxazepam
Lorazepam
Nitrazepam
Alprazolam
(iii) Anticonvulsant drugs
Diazepam
Clonazepam
Lorazepam
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A Textbook of Pharmaceutical
Chemistry
(b) Non-benzodiazepines
Zopiclone
Zolpidem
(c) Barbiturates
(i) Long-acting barbiturates
Phenobarbitone
(ii) Short-acting barbiturates
Butobarbitone, Pentobarbitone
(iii) Ultra short-acting barbiturates
Thiopentone
Diazepam
Structure:
N
N
Cl
O
Chemical name: 7-Chloro-1-methyl-5-phenyl-3H-1, 4-benzodiazepin-2-one.
Uses: In anxiety, vertigo, as a sedative or tranquilizer agent.
Formulation: Solid dosage form (Tablet).
Brand names: VALIUM and CALMPOSE.
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