Past exam of the medicine course of the University of Oxford / 1864 / Second examination / Materia medica, pharmacy (No. II.)

Original volume: Examination papers for the Degree of Bachelor of Medicine by the University of Oxford (1864–1867). PDF volume p. 17; Oxford, 2 December 1864. Open the original paper in the scanned volume.

Original questions are transcribed from the public-domain edition. Credit: Wellcome Collection; original supplied by Royal College of Physicians, London. Source and public-domain rights statement.

What officinal preparations of the British Pharmacopœia contain Opium, and in what proportions ?

The 1864 preparations contain either crude opium or its aqueous Extractum Opii; those quantities must be distinguished from a quantity of isolated morphine. The following are the officinal opium preparations. Ratios for solids mean the mass fraction in the compounded preparation; liquid strengths specify mass per volume or the actual ingredients used.

The arithmetic uses the new avoirdupois ounce of 437.5 grains, not the old apothecaries' ounce of 480 grains. These are historical formulation proportions, not modern assays of morphine delivered after solvent extraction. Confectio Opii was omitted in 1864, and this edition's Vinum Opii contains no spices. The separate morphine hydrochloride preparations—Liquor Morphiae Hydrochloratis, Suppositoria Morphiae, Trochisci Morphiae, and Trochisci Morphiae et Ipecacuanhae—contain an isolated alkaloid salt rather than crude opium. ^[ref]

Mention the chief Diuretics used in England, and give the doses of their several preparations.

The principal period groups were digitalis preparations, squill, broom, juniper oil, buchu, nitrous ether spirit, and several soluble potassium salts. They were grouped by observed promotion of urine flow, rather than by one common mechanism. The following are historical adult quantities per administration, expressed in the contemporary units; they are not present-day prescriptions.

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Other recognised period agents included dandelion and copaiba. The dandelion decoction was given in quantities of 1–2 fluid ounces, its soft extract in quantities of 10–30 grains, and its preserved juice in quantities of ½–2 fluid drachms. Copaiba was given in quantities of 15–30 minims, and copaiba oil in quantities of 5–20 minims. Their historical inclusion does not establish that they are suitable substitutes for current diuretic therapy. ^[ref]

The distinction between preparations matters more than a single “dose of the plant”: an infusion, tincture, juice and powder have different concentrations. Likewise, a salt's small historical diuretic dose is not its larger purgative dose. A modern explanation also separates a direct effect on renal tubules from improved cardiac output in appropriate heart failure: digitalis preparations cannot be understood simply as agents that make every kidney excrete more water. Modern digoxin is used for selected cardiac indications, rather than as a general treatment for low urine output. ^[ref]

Enumerate the “mixtures” for which directions are given in the British Pharmacopœia and state their composition.

The seven named mixtures of the 1864 British Pharmacopoeia are Mistura Ammoniaci, Mistura Amygdalae, Mistura Creasoti, Mistura Cretae, Mistura Ferri Composita, Mistura Guaiaci and Mistura Scammonii. Their compositions are as follows; avoirdupois ounces are used for solids and fluid ounces for liquids.

The category is an official preparation name, not every possible bedside combination of medicines. Camphor water and acacia mucilage are not additional entries under Mistura: the 1864 names are Aqua Camphorae and Mucilago Acaciae. ^[ref]

What is the composition of the Pulvis Jalapæ compositus, of the Pilula Scillæ composita, of the Liquor Morphiæ hydrochloratis, and of the Liquor Strychniæ of the British Pharmacopœia ?

Pulvis Jalapae Compositus contains powdered jalap 5 avoirdupois ounces, potassium hydrogen tartrate 9 avoirdupois ounces, and powdered ginger 1 avoirdupois ounce. Thus the mass proportions are 5:9:1, and jalap supplies one third of the powder's mass. This is a compound purgative, not pure jalap resin. ^[ref]

Pilula Scillae Composita contains powdered squill 1¼ avoirdupois ounces, powdered ginger, ammoniacum and hard soap 1 avoirdupois ounce each, with treacle 2 avoirdupois ounces, or sufficient to make a pill mass. Using the specified 2 avoirdupois ounces of treacle, the whole is 6¼ avoirdupois ounces and contains one fifth squill by mass. The allowance of sufficient treacle makes consistency a compounding requirement, not a claim that every moist pill batch has an analytically exact 20% squill content. ^[ref]

Liquor Morphiae Hydrochloratis contains morphine hydrochloride 4 grains, dilute hydrochloric acid 8 minims, rectified spirit 2 fluid drachms and distilled water 6 fluid drachms. Its conventional strength is ½ grain of morphine hydrochloride per fluid drachm, not ½ grain of free morphine. The small quantity of hydrochloric acid maintains an acid solution. ^[ref]

Liquor Strychniae contains strychnine 4 grains, dilute hydrochloric acid 6 minims, rectified spirit 2 fluid drachms and distilled water 6 fluid drachms. Dissolve the strychnine in the acid mixed with part of the water, using the prescribed assistance of heat, then add the spirit and remaining water. Its conventional strength is ½ grain of strychnine per fluid drachm. Acid promotes solubility by forming a soluble salt of the alkaloid. ^[ref]

For the last two solutions, the stated historical strengths use the nominal 8 fluid drachms of spirit and water. The extra few minims of dilute acid must still appear in the actual recipe; treating all ingredient volumes as perfectly additive would not give an exact modern analytical concentration.

Name the medicines which impart colouring matter to the excretions.

The chief historical examples are rhubarb, senna, santonin and logwood for urine; iron preparations, bismuth preparations and charcoal for darkening the faeces. There are two different processes: a substance absorbed and subsequently excreted can colour a secretion, while material remaining in the intestinal lumen can colour the stools without demonstrating systemic drug absorption.

Colour alone does not identify either the drug or a disease. A medicinal pigment can resemble blood or a bile pigment; pH, timing after administration and appropriate chemical or microscopic examination distinguish possibilities. Conversely, a history of taking a colouring medicine does not prove that an observed specimen contains no blood. These examples describe pharmacological and historical observations, not results from an unseen specimen.

What are the preparations of Iron in the British Pharmacopœia ? For what purpose is Ferri Peroxidum Hydratum used ? How is it ordered to be made ?

The 1864 iron list includes metallic, ferrous, ferric and compound preparations; its wet Ferri Peroxidum Hydratum was used historically as an antidote to arsenic poisoning. It must be distinguished from dried Ferri Peroxidum and from later editions' reassignment of similar Latin names.

The officinal articles and preparations are:

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Prepare the hydrated peroxide by inducing precipitation from the ferric solution with sodium hydroxide, collecting and washing the wet precipitate, and preserving it without drying in a covered vessel. The starting solution is Liquor Ferri Persulphatis, whose “persulphate” here means ferric sulfate, not a modern peroxydisulfate salt. Add the appropriately diluted ferric solution to the alkaline liquor with stirring, allow the precipitate to settle, collect it on a calico filter, and wash with distilled water until the washings no longer give a precipitate with barium chloride. This tests removal of soluble sulfate. The resulting fresh, hydrated material is kept wet; drying gives the separate dried preparation. ^[ref]

In modern chemical notation the precipitation can be idealised asThe fresh solid is a hydrated ferric oxide material with variable water content; the equation is not a claim that every pharmaceutical batch is one pure, crystalline iron hydroxide. Its historical use depended on binding dissolved arsenic into less available material in the digestive tract, especially the freshly precipitated, wet state. It was not a universal antidote to every metal or every stage of absorbed arsenic poisoning. Contemporary discussion explicitly identified the new hydrated peroxide as an arsenic antidote. ^{[ref] [ref]}

Modern treatment of significant arsenic poisoning concerns systemic toxicity and may involve specialist-directed chelation therapy; a nineteenth-century ferric paste is not the modern treatment standard. ^[ref]

What classes of medicines are fitted for preparation by means of decoction and of infusion respectively ? How are liquid extracts made ?

Decoction suits material whose useful constituents are water-soluble and withstand boiling; infusion avoids sustained boiling and can better preserve delicate or volatile constituents. The choice depends on both the plant's structure and the chemistry of the constituent being extracted.

Hard bark, wood and many kinds of root need comminution and more prolonged contact with hot water to penetrate their tissues; a decoction can assist extraction when the desired material is stable. Boiling is unsuitable when it drives off a needed volatile oil, decomposes the active constituent, or extracts an unwanted excess of starch or other material. A hard root is therefore not automatically an instruction to boil. Period examples suitable for decoction include oak bark, logwood and pareira root; appropriate infusions include aromatic cloves and chamomile. Cold infusion of calumba avoids dissolving its starch, illustrating that suitability depends on the desired selectivity of solvent extraction, not merely on whether a drug is a leaf or a root. ^[ref]

For an infusion, the appropriately divided drug is left in a measured solvent for a prescribed time, commonly in a covered vessel. Hot water assists extraction, while a cover reduces loss of volatile matter. Cold infusion can be chosen when heat is undesirable. The result must be strained or filtered; time, temperature, particle size and solvent quantity affect its strength. Neither method guarantees that every constituent is extracted in the same proportion.

A liquid extract is made by extracting the specified drug with a suitable solvent, separating the liquid from the exhausted material, and bringing the extract to its prescribed concentration and volume. Maceration can precede percolation; expression or washing recovers retained liquid. A percolator passes fresh solvent through a packed bed, rather than indefinitely soaking the drug in an increasingly saturated liquid. Where concentration is necessary, controlled evaporation limits damage; an alcoholic fraction can be reserved or recombined as the monograph directs. Different liquid extracts can use aqueous, alcoholic or ethereal processes. For example, the liquid extract of male fern is an ethereal extraction of a resinous and oily fraction, whereas the liquid extract of opium is compounded from a previously made aqueous extract. These are chemically different operations. There is no warrant for assigning all 1864 extracts one modern universal drug-to-extract ratio. ^[ref]

What is the temperature at which Linseed, Mustard, Charcoal, and Yeast Poultices are to be made ?

For the contemporary formulary, use boiling water for the linseed, charcoal and mustard poultices, and water at 100°F for the yeast poultice. These are preparation temperatures, not temperatures at which boiling material is placed on skin.

For Cataplasma Lini, hot water hydrates the ground linseed into a cohesive moist mass; the contemporary account also notes the addition of olive oil when oil has been removed from the meal. For Cataplasma Carbonis, the hot bread-and-linseed basis is made with boiling water, then the charcoal is incorporated and part used at the surface. At ordinary atmospheric pressure the boiling-water preparation temperature is approximately $\boxed{212{}^{\circ }\mathrm{F}=100{}^{\circ }\mathrm{C}}$. ^[ref]

For Cataplasma Fermenti, the stated $\boxed{100{}^{\circ }\mathrm{F}\approx 37.8{}^{\circ }\mathrm{C}}$ permits the yeast to ferment the flour mixture. Boiling would injure its fermenting activity. The flour, yeast and warm water are mixed and kept warm while the mass rises. This is a historical compounding process, not evidence that a fermented dressing treats every wound. ^[ref]

The mustard entry requires a historical qualification. The contemporary British recipe reproduced by the text directs powdered mustard and linseed to be mixed, then stirred into boiling water; the same text observes that excessive heat impairs development of the pungent volatile oil. Thus “boiling” is the contemporary formula's instruction, while lukewarm preparation better preserves development of mustard's pungent volatile oil. These are different claims. The later practical preference for lukewarm water should not silently replace the 1864 recipe, nor should that recipe be mistaken for optimal modern biochemical practice. ^[ref]

Explain the principle of Volumetric Analysis.

Volumetric analysis determines an amount of substance from the measured volume of a reagent of known strength that reacts with it in a known proportion. A measured aliquot is placed in a suitable vessel, the standard solution is delivered from a burette, and the volume required to reach the chosen titration endpoint is read. A pipette measures the aliquot; a volumetric flask prepares or dilutes the standard solution.

For a reaction $aA+bB⟶\text{products}$, if the concentration of the titrant $B$ is $c_B$ and the corrected volume delivered is $V_B$, thenWith volume in litres and concentration in moles per litre, the answer is an amount in moles. The corresponding mass is $m_A=M_A{n}_A$, using the appropriate molar mass. For an unknown solution of aliquot volume $V_A$,These are modern symbols for the same proportional reasoning that a nineteenth-century analyst could express with equivalent weights and a specified standard solution.

A suitable reaction is sufficiently rapid, complete and selective, with a recognisable endpoint. In an acid-base titration, an indicator can change colour near neutralization; other reactions use precipitation, redox or a colour intrinsic to a reagent. The observed titration endpoint must represent the required equivalence point closely enough. The reagent's nominal preparation alone is insufficient if its concentration changes in storage; standardisation of a solution, a reagent blank where needed, and correct reading of the meniscus control systematic error. A titration measures the intended analyte only insofar as interfering substances have been excluded or accounted for.

Give the equivalents of the weights and measures employed in the British Pharmacopœia, in French weights and measures.

The 1864 solid units are the avoirdupois pound, avoirdupois ounce and grain; the liquid units are the Imperial measures. The grain is unchanged, while the old apothecaries' pound and ounce are not the units of the new formulary. ^[ref]

The relations for solids areTheir approximate French metric equivalents are:

For liquids,The approximate metric volumes are:

A millilitre is a cubic centimetre, and a litre is a cubic decimetre. These displayed equivalents are rounded; small differences from a period table's last digits reflect rounding and historical calibration conventions. A fluid ounce is a volume and an avoirdupois ounce is a mass. They cannot be interchanged for an arbitrary liquid without its density. Likewise, a drop is not a defined minim: its volume depends on the liquid and the dropper.