A considerable part of Homoeopathic materia medica consists of medicines taken from animal kingdom. As the name implies, the Ophidia group consists of medicines taken from snakes.
Ophidia comes under Class Reptilia, which comes under Phylum Chordata, under metazoa. The other Classes in Phylum Chordata includes Pisces, Amphibia, Aviens and Mammalia.

 There are mainly 15 medicines in the Ophidia group. They are 

1) Lachesis [ lachesis/ lachesis muta, proved by Hering]
2) Crotalus horridus [ Bush master-proved by Hering]
3) Crotalus cascavella [ rattle snake or pit viper, proved by Mure, comes under the N.O.-Crotalidae]
4) Naja tripudiens [ naja; cobra; Elapidae]
5) Elaps corallinus [ Snake; Micru rus corallinus]
6) Bothrops lanceolatus [ viper yellow.Lach lanceolates)
7) Vipera torva (german viper)
8) Vipera communis(common viper)
9) Vipera jedi
10) Cenchris contortrix [ head snake; Ancistrodon]
11) Bungarus fasciatus [ krait]
12) Toxicophis [ snake]
13) Hydrophis cyanocinctus
14) Clotho arictans [ adder]
15) Ophiotoxinum
 
Sources of drugs
The poison taken from the snakes. Chemically, the snake poisons are cyanhydrates of soda and other salts.
Alcohol is a natural solvent and an antidote for these poisons.

The major poisonous snakes, the poi son of which are made use of in homoeopathy are
I) Viper [ including pit vipers of crotalidae]
2) Cobras [Naja)
3) Kraits [Bungarus)
4) Sea snakes [Hydrophis)
 
Snake Venom
The Snake Venom is the modified saliva. The venom contains nine enzymes such as
(i) Phosphatidases
(ii) Proteases
(iii) Cholinesterases
(iv) Hyaluronidases
(v) Ribonucleases
(vi) Deoxyribonucleases
(vii) Ophioxidase
(viii) Lecithinase
(ix) Crepsins
 
(1)In addition Cobra and Krait venoms also contain highly neurotoxic non enzymatic components like basic polypeptides, which cause neuromuscular block.
(2) Viperine venom contains haemorrhagic, necrotic, coagulant and haemolytic substances which lead to extensive necrosis.
Lesions are due to intravascular coagu lation, fibrinolysis, damage to vascu lar endothelium and extensive necrosis
(3) Venoms of Sea snake are neurotoxic. They can also cause extensive tissue
 
Speed of action of Venom:
This depends on the site of injection and the amount injected. If the venom directly enters the blood stream, effect may be rapid and lead to sudden death. In most of the cases, the absorption of venom is slower and especially in Viperine bites With extensive local reaction, considerable amount of venom may remain locally which will be absorbed into the circulation in due course.
 
Effect or Clinical features of snake bite:-
I. Immediate response-
Seen in all snake bites. There will be severe fright and mental agitation leading to tachycardia, sweating, hypotension and even vascular collapse.

II. Local reactions:
This is seen more in Viperine bites than in others. There will be intense pain, swelling and violaceous discolouration, developing within minutes and often a sero sanguinous fluid exudes from the fang marks.
Oedema and discolouration spread proximally and in a few hours, vesicles and haemorrhagic blebs may appear.

III. General effects:
The general effects vary with the type of snake.
Cobra and sea snake venoms are pre dominantly neurotoxic Viperine venom is histotoxic and haemorrahagic.
There will be some overlapping of the effects during certain seasons. 

IV. Cobra and Krait bites:
They are neurotoxic. Soon after the bite, the patient complains of a sinking feeling, drowsiness, blurring of vision, diplopia, dysphagia and dyspnoea. There will be paralysis of palate, tongue, pharynx and respiratory muscles. There’ll be a flaccid paralysis of the limbs, associated with hypotonia and a diminution in the tendon reflexes.  Coma and death can happen due to respiratory failure or shock in 6-48 hrs. Sometimes the symptoms may present as acute myasthenic crisis. 

V. Viperine bites:
It is histotoxic and haemorrhagic. Within 3-4 hours of bite there will occur the following features.

(ii) Haemorrhagic manifestations, which appear as extensive bruises, bleeding from the bitten parts, bleeding from gums, epistaxis, blotchy purpura haemorrhagica, haématemesis and malena. Bleeding can lead to shock.
Cardiac manifestations occur as tachycardia, myocarditis and cardiac failure.

(iii) Rarely, there’ll be optic neuritis lead ing to partial or complete blindness in 2-7 days.
Renal changes occur as proteinuria and haematuria. A dreaded complication due to direct nephrotoxicity is anuric renal failure, the lesions of which are acute tubulonecrosis, haemorrhagic interstitial nephritis and acute glomerulonephritis.
Death in Viperine bite occur due to shock, haemorrhages, secondary infection, renal failure or cardiac failure.

VI. Krait venom is neurotoxic. They present with symptoms similar to co bra bite but is most lethal. Local reaction is minimal. 

VII. Sea Snakes-Their venom is neurotoxic and nephrotoxic. There’ll be pain and stiffness of muscles of neck, back and proximal part of limbs. Trismus, ptosis, etc. Ophthalmoplegia and paralysis and the symptoms may lead to respiratory failure. Proteinuria and myoglobinuria occurs. Death is due to respiratory paralysis and renal failure.

 
    Common Characteristics of Ophidia

I. Paralysis
Features of typical bulbar paralysis occur in Naja.
The paralysis of Ophidia group occur in right side as well as left side.
Right side
(1) Crotalus horridus
(2) Crotalus cascavella right sided hemiplegia.It is complementary to Lachesis as it completes the curative action.)
(3) Elaps corallinus
(4) Bothrops-hemiple gia with aphonia 
Left Side
(1) lachesis has left sided paralysis especially from apoplexy.
There will be extensive paralysis
Naja: Bulbar paralysis, sphincter control will be lost.
Vipera: Paraplegia of lower extremities, re sembling acute ascending paralysis of Landry.
Bangarus fasciatus: Acute polioencephalitis and myelitis. 

II. Constriction of throat - larynx & sphincters
(i)Lachesis: Constriction of throat, larynx and abdomen, with intolerance to least touch or pressure, especially on neck. There’ll be constriction in rectum. Anus will feel tight. There will be dysphagia for liquids as in Bothrops.
(ii) Cenchris contortrix: There’ll be constriction as in Lachesis with the neces sity for having the clothes loose. There will be vivid dreams. Like Arsenic alb, there’ll be dyspnoea; Mental and physical restlessness; Thirst for small quantities of water.
(iii) Elaps: There’ll be constriction of pharynx. Food and drinks are suddenly arrested and “ fall heavily into stomach.”
(iv) Crotalu horridus: There’ll be spasms o The patient is not able to swallow any solid substances. There’ll be an intolerance to clothing around stomach.
(v) Vipera: Tears his clothes open due to violent congestion in chest. There’ll be “Cardiac anguish with violent, chest pains.”
(vi) Naja: Grasping throat with a sense of choking. There will be asthmatic constriction in evening.
(vii) Bothrops- There will be constriction in throat with difficulty in swallowing, especially towards liquids.  

III. Haemorrhages of dark, non-coagulable decomposed black blood oozing from all orifices of the body with ecchymosed. 
(i) Lachesis: Oozing of dark, decomposed blood, purpura with intense prostration, epistaxis, bleeding gums. There will be haemorrhages from bowels like charred straw, black particles. There will be a general relief by menstrual flow.
(ii) Crotalus horridus: Dark non-coagulating blood; haemorrhagic diathesis; retinal haemorrhages. Blood oozes from ears. There’ll be epistaxis where the blood will be black and stringy: persistent haemorrhages; intestinal haemorrhage; bloody urine; purpura haemorrhagica; bloody sweat.
(iii) Elaps: Epistaxis; Haemorrhages from lungs as black ink. Watery haemorrhage with pain in the apex of right lung. There will be cough with expectoration of black blood. Menstrual bleeding is black In typhoid fevers when ulcers have eaten into tissues, there’ll be the discharge of black blood.
(iv) Bothrops: Haemcirrhages from all orifices, b leading to hemiplegia aphasia and dysarthria; conjunctival and retinal haemorrage; bloody stools.
(v) Vipera-Persistent epistaxis; affects especially the veins.

IV. Inflammations and fevers of low destructive type 
Eg: gangrene, cellulitis, malignant ul cerations, diphtherIa and typhoid etc.
(i) Lachesis; Septic states, diphtheria and other low forms of diseases with pro found prostration. There’ll be boils, carbuncles and ulcers with bluish purple surroundings; pyaemia, dissecting wounds,bedsore with black edges. bluish or baickish swellings.
(ii) Crotalus horridus: Low septic states; carbuncles; malignant scarlatina; yellow fever, plague, cholera etc. Boils, carbuncles and eruptions are surrounded by purplish, mottled skin, and oedema; lymphangitis; septicaemia.
(iii) Bothrops: Cold, swollen skin with haemorrhagic infiltrations; gangrene; lymphatics swollen; Anthrax; m erysipelas.
(iv) Vipera: Lymphangioma, boils, carbuncles with burning sensation, relieved by elevating parts Skin peels off in large plaques.   

(v).Nerves, specially affected by snake poisons
(I) Vagus nerve
(ii) Spinal accessory nerve ,So, characteristically we get symptoms of larynx, respiration and heart.
Ophidia medicines cause choking constrictive sensation due to pneumogastric nerve irritation.
Weak heart, cold feet and trembling.
All the medicines have dyspnoea and cardiac symptoms  

VI. Yellow staining or colour of skin
Most marked in Cortalus horridus, less in Lachesis and Vipera communis and Vipera torva.

VII. Action on heart-Produce palpitation, dyspnoea and valvular lesions. 
(i) Naja: Heart rhythm is regular, but the force of c3ntractio1rr indicated in remote effects of advanced valvular lesions. There’s a well marked frontal and temporal headache with the cardiac_symptoms. Patient is always gasping for breath.
(ii) Lachesis: Indicated in the of rheumatic heart diseases. Palpitation with fainting spells especially during the clirnacteric period; Cyanosis.
(iii) Crotalus horridus: Palpitation,espe cially during menses. Heart’s actions feeble.
(iv) Vipera-Cardiac dropsy 

VIII. Appearance of face
Sickly, pale, anxious, bloated swollen, dark red or bluish, especially in Lachesis, Bothrops, Vipera. The face is yellow in Lachesis and Crotalus. 

IX . Alteration of spinal reflexes-
Dimness of vision, excitability of brain or spinal cord resulting in mental restless ness and physical sensitiveness
Torpidity, numbness twitching and formication. 

X. Initial anxiety, mental excitability and over sensitiveness
Hallucinations and fear, followed by nervous depression which varies from debility to confusion, stupor, delirium and paralysis.

XI. Periodicity:
Vipera : Symptoms return anually for years
Thxicophis: Pain and fever return an nually, sometimes changing location with disappearance of the first symp toms.
Lachesis: Complaints, especially the intermittent fever, returning in every spring. 

XII. Swelling
(i) Clotho arictans: Excessive swelling is the characteristic feature
(ii) Toxicophis: Oedematous swelling
(iii) Naja: No haemorrhage; only oedema. 
XIII Climacteric ailments:
(1) Lachesis: Haemorrhages, haemorrhoids; hot flushes, hot per spiration; burning in vertex, headache at or after menopause.
(ii) Crotalus horridus: Intense flushings and drenching perspiration. Profound anaemia. Prolonged metrorrhagia; dark offensive fluid; faintness and sinking at stomach.
(iii) Vipera: Climacteric ailments. 

XIV. Mental Symptoms:
(i) Fear of rain: Elaps, Naja
(ii) Dreams of dead persons: Elaps, Cro talus horridus, Crotalus cascavella
(iii) Dreads to be left alone: Elaps, Naja 

XV. Action on liver –
 Hepatomegaly and Jaundice
(i) Lachesis- Liver regions sensitive. Can’t tolerate clothing around waist
(ii) Crotalus- Haemolytic jaundice; yellow conjunctiva and skin
(iii) Vipera: Violent pain. Enlarged liver with jaundice and fever pains extend to shoulder and hip 

XVI. Sleep aggravation
(i) Lachesis: As soon as the patient falls asleep, breathing stops
(ii) Croralus horridus: Sleeps into his symptoms
(iii) Naja: Suffocative spells after sleeping 

XVII. Dysarthria:
(i) Bothmps: Hemiplegia with aphasia; in ability to articulate without any affect tion to tongue.
(ii) Vipera: Speech is difficult
(iii) Naja: Blurred speech (bulbar paralysis)
 
References: -
I) Clinical Materia Medica-E.A. Farrington
2) Comparative Materia Medica-E.A. Farrington
3) Pocket Mannuel of Homoeopathic Materia media-William Boerick
4) Dictionary of Practical Materia medica-JH Clarke
5) Homoeopathy-The Principles and practice of treatment-Andrew Lockie & Nicoloa Jeddes.
6) New Comprehensive homoeopathic materia medica of the mind H.L.Chitkara
7) Text book of Medicine-Dr.K.V. Krishnadas.