Prescription‐only‐medicines: Veterinarian (POM‐V) [5]

Only a vet can prescribe medications from this category. On 1^st September 2023, the RCVS under care guidance changed. This meant that vets no longer had to carry out a physical assessment of an animal to take them ‘under their care’. Under the new guidance published by the RCVS, a vet can accept an animal as ‘under their care’ when they are given and accept responsibility for it. Before prescribing a POM‐V medication for an animal, the vet must carry out a clinical assessment. According to the new under care guidance, it is now up to the vet to decide whether this clinical assessment needs to include a physical examination or not, except for a number of circumstances which are as follows:

• Where a notifiable disease is suspected
  
• When prescribing controlled drugs (unless there are exceptional circumstances)
  
• When prescribing antibiotics, antifungals, antiparasitics or antivirals (unless there are exceptional circumstances^*)
  

  ^*NB The proximity of physical examination to prescribing will be slightly different depending on the species being treated)

Please see the Further Reading section for more information.

A written prescription is NOT required if the vet supplies the medication; however, clients with animals on long‐term medications may request a written prescription to enable them to buy the medicines on the internet. Before prescribing the medication, the vet must be satisfied that the client or the person administering the medication (yard owner, for example) is going to administer the medication correctly. Therefore, they must assess the competency of the client before prescribing the medication.

• Updated lists of POM‐V medications can be found on the veterinary medicines directorate (VMD) website at https://www.gov.uk/government/organisations/veterinary‐medicines‐directorate.

Veterinary medicinal products (VMPs) categorised as a POM‐V often have one or more of the following:

• A new active ingredient
  
• Safety concerns
  
• It is deemed that veterinary knowledge is required for the use of the product
  
• The drug has a narrow safety margin
  
• Government policy

Medicated feedstuffs tend to now sit in the POM‐V category [9].

Prescription‐only Medicine – Veterinarian, Pharmacist or Suitably Qualified Person – (POM‐VPS) [7]

• These medications can only be supplied by a Veterinarian, Pharmacist or a Suitably Qualified Person (SQP). The animal medicines training regulations authority (AMTRA) now use the term; registered animal medicines advisor (RAMA).
  
• The prescription can be in writing or oral, and a clinical assessment is not necessary.

A VMP is generally classified as a POM‐VPS when it has the following characteristics:

• It is used to prevent endemic disease in herds, flocks or individual animals.
  
• There is some risk for the user, consumer, animal or environment. However, users can be advised of this by verbal or written instructions.
  
• Adequate training can be given for the regular use.

Non‐food Animal Medicine – Veterinarian, Pharmacist, Suitable Qualified Person (NFA‐VPS) [7]

• These medications can only be supplied by a Veterinarian, Pharmacist or a Suitably Qualified Person (SQP).
  
• The prescription can be in writing or oral, and a clinical assessment is not necessary.
  
• It must be a non‐food‐producing animal.

Authorised Veterinary Medicine – General Sales List (AVM‐GSL)

• Any retailer may supply it; there is no restriction on their supply.

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  Classification	Meaning	Types of medicines	Examples
  CD	Controlled drugs	Prescription‐only medicines that are also classified under the Misuse of Drugs Regulations 2001	Opioid analgesics
  POM‐V	Prescription‐only Medicines – Veterinarian	Medicines can be supplied with a valid prescription from a Veterinarian	Analgesics, antimicrobials
  POM‐VPS	Prescription‐only medicines – Veterinarian, Pharmacist, Suitably Qualified Person	Medicines can be supplied with a valid prescription from a Veterinarian, Pharmacist or Suitably Qualified Person	Anthelmintics
  NFA‐VPS	Non‐Food Animal – Veterinarian, Pharmacist, Suitably Qualified Person	Medicines can be supplied without a valid prescription from a Veterinarian, Pharmacist or Suitably Qualified Person	This category is not applicable to horses as they are considered to be a food‐producing species. For cats and dogs, some topical ectoparasite treatments fit into this category
  AVM‐GSL	Animal Veterinary Medicine – General Sales List	Can be supplied by most retailers such as supermarkets and pet shops	Dietary supplements and insect repellents
  SAES	Small Animal Exemption Schemes	Allows certain medicines to be sold without marketing authorisation for certain animals not intended for human consumption	Some anthelmintics for small animals

  
  
• VMPs are placed in this category when:
  
  
  
  • There is a wide safety margin
    
  • They are used for common ailments
    
  • Special advice on their use is not required.

Table 9.1 summarises the legal categories of drugs in the United Kingdom.

Medication Storage

Proper medication storage is critical when working within a pharmacy. It is essential to know the temperature ranges specified within the data sheets, which can be found under pharmaceutical particulars. Correct storage prevents damage or inactivation of the products.

Considerations for temperature ranges are as follows:

• Some medicines require storage between 2 and 8 °C. Products can be irreversibly degraded if the temperature goes outside of this range, even briefly, so monitoring storage temperature is vital.
  
• The temperature of any refrigerators being used to store veterinary medicines should be monitored daily. A maximum/minimum thermometer should be used and this should be read and reset daily. All temperatures should be recorded. Continuous data loggers to monitor the temperature are now widely used as these are convenient. However, these should only be used if an audible alarm or flashing light alarm alerts the user to temperatures deviating from the required range. Weekly downloading of the temperatures into graph format is helpful to determine trends in temperature fluctuations. The problem with this is that without an alarm system, deviations from the required ranges will not be noticed until the data is downloaded. Data from these systems should be downloaded at least weekly [5].

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  Species	SQP code	AMTRA	VetSkill	Vetpol
  Companion, Equine + Farm	R	80 points in 2 years	15 h (10 h CPD/5 h personal study)	6 h per year (3 for RVNs)
  Farm + equine	G	60 points in 2 years	10 h (5 h CPD/5 h personal study)	5 h per year (2.5 for RVNs)
  Farm + companion	K	60 points in 2 years	10 h (5 h CPD/5 h personal study)	5 h per year (2.5 for RVNs)
  Equine + companion	E	50 points in 2 years	10 h (5 h CPD/5 h personal study)	5 h per year (2.5 for RVNs)
  Farm only	L	50 points in 2 years	5 h per year	3 h per year (1.5 for RVNs)
  Equine only	J	30 points in 2 years	5 h per year	3 h per year (1.5 for RVNs)
  Companion only	C	30 points in 2 years	5 h per year	3 h per year (1.5 for RVNs)
  Avian only	A	30 points in 2 years	5 h per year	3 h per year (1.5 for RVNs)
  Companion + avian	CA	40 points in 2 years	10 h (5 h CPD/5 h personal study)	5 h per year (2.5 for RVNs)
  Equine + avian	JA	40 points in 2 years	10 h (5 h CPD/5 h personal study)	5 h per year (2.5 for RVNs)
  Equine, companion + avian	EA	60 points in 2 years	15 h (10 h CPD/5 h personal study)	6 h per year (3 for RVNs)
  Avian and farm	AL	Not applicable (N/A)	10 h (5 h CPD/5 h personal study)	5 h per year (2.5 for RVNs)
  Companion, avian + Farm	CAL	N/A	15 h (10 h CPD/5 h personal study)	6 h per year (3 for RVNs)
  Avian Equine + farm	S	N/A	15 h (10 h CPD/5 h personal study)	6 h per year (3 for RVNs)
  Companion, equine, avian + farm	XA	N/A	15 h (10 h CPD/5 h personal study)	7 h per year (3.5 for RVNs)

  
  
• Some medicines require storage at temperatures below 15 °C. Since most practices do not have a cool room, a refrigerator would provide appropriate storage for such products, provided storage below 8 °C does not affect the medicine.
  
• Medicines that require storage at 25 °C or below can usually be stored at room temperature. Depending on the location of the pharmacy within the practice and the environmental temperatures reached, air conditioning may be required to maintain a stable ambient temperature. The ambient temperature must be monitored and recorded to ensure that the pharmacy meets the RCVS practice standards scheme (PSS) requirements [16].
  
• Excessive heat (greater than 40 °C) may be a cause for concern for ambulatory vets as temperatures within the car are often much higher than the ambient temperature [16]. Steps must be taken to ensure that the storage requirements are maintained even when stored in vehicles. Each vehicle must have a working fridge complete with temperature monitors. Insulated medication storage boxes should be used to minimise the temperature increase in extremely hot weather, and minimum and maximum thermometers should be used to monitor the temperature of vehicles and the medications kept within them.
  
• Light‐sensitive medications should be stored in coloured bottles, and if dispensed in smaller quantities, they should be dispensed in coloured bottles [21].

Quinalbarbitone

• This drug is currently classified as a Schedule 2 CD, but it does not require safe custody (i.e. it does not need to be kept in the CD cabinet). However, it is good practice to keep it secure.
  
• It does need to be recorded in a CD Register [5].

Buprenorphine

• This drug is classified as a Schedule 3 CD, and its use does not need to be recorded in the CD Register, but safe custody does apply (i.e. it does need to be kept locked in a CD cabinet) [5].

Midazolam

• Midazolam has been moved from Schedule 4 to Schedule 3, and therefore, prescription requirements apply.
  
• It does not need to be kept in the CD cabinet although the RCVS recommends that all Schedule 3 CDs are kept in the CD cabinet. Recording in a CD register is not required [5].

Vetsafe

The Veterinary Defence Society (VDS) has launched Vetsafe. This is a confidential significant event reporting service that is used for quality improvement purposes and to aid in risk management in veterinary practice. This involves a log of incidences of patient harm or other losses and also near misses in practice. It is essential to understand that even highly trained and motivated professionals make mistakes. The aim of VetSafe is to help practices learn from mistakes without allocating blame or judgement on co‐workers [24].

VetSafe can:

1. Help clinicians to understand why mistakes happen
   
2. Help practices develop solutions to improve the quality of care
   
3. Share learning
   
4. Help practices track significant events and comply with the RCVS PSS
   
5. Support second victims – clinicians involved in mistakes [24]

Pharmacovigilance

According to the World Health Organisation (WHO), pharmacovigilance is the science relating to detecting, assessing, understanding and preventing adverse effects or any other medicine/vaccine‐related problem [25].

The VMD are responsible for obtaining information from veterinary professionals, members of the public and pharmaceutical companies on adverse reactions. The information received is vital in monitoring the safety of veterinary medicines and identifying previously unknown hazards or side effects [24].

For a product to remain authorised for use, the benefits of administering the product must outweigh the risk of suffering reactions; if the risks outweigh the benefits, the product will be removed from the market. The adverse reaction reports allow the VMD to assess the risks and act appropriately, including updating the product literature with potential side effects [24].

Record Keeping

The CD section above covers record keeping for CDs. Plenty of other records are to be kept within veterinary practice.

POM‐V and POM‐VPS drugs: records must be kept, including incoming and outgoing transactions to include:

• Date of receipt and supply, which includes administration by the vet.
  
• Name and quantity of the VMP.
  
• Name and address of the supplier or recipient.
  
• If there is a written prescription, the name and address of the person who wrote the prescription and a copy of the prescription.
  
• Batch number (for products used for non‐food producing animals, the batch number only needs to be recorded either on the date of receipt of the batch or the date the batch is first supplied or used).
  
• The purpose of recording batch numbers is to provide traceability of specific batches of products. This is intended to provide a basis for effective recall of a batch or batches of a product should this become necessary and provide traceability of the use of medicines in food‐producing animals.
  
• Whether or not the cascade has been used [5].

All the above records should be kept for a minimum of five years [7].

Drug Use and Dispensing

When supplying POM‐V medicines, they should be dispensed with an appropriate label with the following information:

• Name and address of the owner
  
• Name and address of the approved premises
  
• Date of supply
  
• Keep out of reach of children
  
• For animal treatment only
  
• For external use only
  
• Name, quantity, strength and directions for the use of the product [7]

Broached Vials

The broach date for vials should adhere to the information found on the datasheet. Most vials are to be used within 28 days of first broaching; however, some time periods are shorter. For example, reconstituted Excenel should be used within 7 days of first being broached and should be kept in the fridge thereafter [7, 20].

Out‐of‐date Stock

It is illegal to supply or administer a medicine after the expiry date detailed on the packet or to obscure the expiry date on the packaging of any medicine. Requirements in the European Union (EU) and national legislation to ensure the stability and safety of the products, mean that some products, such as injectables, have an in‐use shelf‐life. This is the timeframe in which a drug must be used after it has been broached, and this must remain within the expiry date of the drug. The following points should be followed in relation to out‐of‐date stock [26]:

• For most multidose injectables, the in‐use shelf‐life is usually, but not always, 28 days, thus making it an offence to administer the product 28 days after the first day of broaching. Multidose vials should be marked with the date of broaching and use‐by date.
  
• Bright‐coloured stickers can be helpful to draw attention, but all multidose vials with an in‐use shelf‐life now have a space to write this information on the bottle.
  
• Any medicine left in the vial after the specified time must be discarded. The required dose should be withdrawn immediately, and the remainder disposed of for single‐use ampoules.
  
• Oral liquids should generally be disposed of six months after opening.
  
• When date checking, the short‐dated stock should be marked and brought to the front of the shelf to be used first.
  
• Any stock that has gone out of date should be separated and details should be recorded before disposal.

CDs

All CDs must be destroyed by denaturing to render them irretrievable, but only the destruction of Schedule 2 CDs requires independent witnessing. There are commercially available denaturing kits used to destroy out‐of‐date stock CDs and returned CDs. These kits contain granules that react with liquids to form a solid gel. Drugs in liquid form should be removed from ampoules and vials and poured into the denaturing kit. Fentanyl patches can be folded upon themselves and placed in the gel with everything else, and tablets should be crushed, mixed with water and added to the gel [22].

The container should then be stored in a locked cabinet for 24 hours to allow the gel to solidify. The container is then sent as pharmaceutical waste through the practice waste contractor. Residual CDs are not usually denatured in this way because their destruction is required daily, which would prove too costly. Instead, residual drugs can be rendered irretrievable by collection into cat litter. Periodically, this cat litter is sent to the waste contractor as pharmaceutical waste [5, 22].

CDs may be presented for destruction in three different circumstances:

• Residual or waste drug – a whole ampoule of a CD (e.g. 10 mg morphine) is dispensed to a patient, but only 5 mg is administered to the patient, and the remainder is denatured. The amounts administered and denatured are recorded on the same line of the CD register to ensure the whole vial is accounted for. Double signing is good practice. This does not have to be witnessed by an independent person.
  
• Out‐of‐date drug stock. Destruction of out‐of‐date stock falls under the Misuse of Drugs Regulations (2001) and must be witnessed. This includes expired ‘in‐use shelf‐life’ (e.g. a part‐used bottle of methadone which has been open for more than 28 days). The expired stock should be kept in the cabinet, labelled appropriately and separated from in‐date drugs. It should not be marked out of the running balance in the CD register until it is destroyed.
  
  
  
  • For Schedule 2 CDs, the destruction must be witnessed by an RCVS Assessor or VMD inspector, a controlled drug liaison officer (CDLO) from the police force (a list of CDLOs can be found on the Association’s website) or an independent vet.
    
  • In order to be considered independent of the practice, another vet must have no personal, professional or financial interest in the practice where the drug is destroyed (i.e. locum team members or family members cannot do this).
    
  • The independent vet must not be paid to witness the denaturing, apart from reasonable travel expenses. The RCVS number of the independent vet should be recorded in the CD register.
    
  • For Schedule 3, 4 and 5 CDs, destruction does not need to be witnessed by an independent witness, but it is good practice to have it witnessed by another team member [5].
  
  
• Returned drug: The drug has been dispensed to a patient; there is no requirement to have the destruction of this drug witnessed or recorded. However, it is good practice to witness it with another staff member [22].

Route of Administration

There are many routes of drug administration, but the most commonly used in equine medicine are oral, topical, S/C, IM and IV. Generally, for a drug to reach its site of action and have an effect, it must enter the systemic blood circulation; the route of administration will affect how long this takes. The only exceptions are drugs that act locally, i.e. they are applied directly to the area they work on. Mepivacaine hydrochloride is an example of a locally acting drug that does not need to enter circulation to reach its site of action [33].

Bioavailability refers to the amount of a drug that reaches the circulation intact. Medications given via the IV route have 100% bioavailability due to no absorption phase; this means the body can utilise 100% of the drug. This is also known as the bioavailability of one. Medications given by all other routes are said to have a bioavailability of less than one, as less than 100% of the dose will reach the circulation intact. Bioavailability is affected by the rate at which the drug is absorbed and the ease of absorption. Generally, the better the blood supply to an area, the quicker the absorption rate. Drugs administered intramuscularly are usually absorbed quickly. S/C injections have the lowest bioavailability due to the skin having a poor blood supply and some of the medication will be lost in the S/C fat [33].

Orally administered drugs travel through the gastrointestinal tract, which leads to large quantities being absorbed by the small intestine. Liquid preparations are generally absorbed more quickly than tablets, capsules and granules, as these need to undergo a dissolving process known as dissolution before absorption can occur. Some oral drugs are formulated as a ‘sustained release’ preparation, where dissolution and subsequent absorption are slowed. Sustained release is not the same as a tablet that is enteric coated; these tablets have been developed to protect the medication from the acid within the stomach. After an oral drug is absorbed across the intestinal wall, it enters the hepatic portal circulation, which directly transports it to the liver. One of the roles of the liver is to remove potentially toxic substances before they reach systemic blood circulation. Drugs may be partially or wholly broken down because of this mechanism, known as the first‐pass effect. The first‐pass effect is one reason that some medications cannot be administered orally or that the dose rate of an oral preparation is much higher when compared with a parenteral preparation of the same drug. Due to the need for dissolution, the time taken to reach the absorption site, and the first‐pass effect, orally administered drugs tend to have a comparatively low bioavailability [33].

Other factors also affect the rate of absorption:

• Tissue perfusion directly affects the absorption rate; for example, a drug injected into an active, well‐perfused muscle is absorbed more quickly than one injected into an inactive muscle due to a limited blood supply [33].
  
• Vasoconstriction or vasodilation will cause reduced or enhanced blood flow to an area, so exposing the patient to cold or hot environmental temperatures will affect the absorption rate when injecting via the S/C route.
  
• Disease conditions that affect the perfusion of the horse, shock and peripheral vasoconstriction both affect the absorption [33].
  
• The formulation of a drug can significantly influence its absorption. Hydrophilic drugs dissolve more easily in water, while lipophilic drugs dissolve more easily in fat. When drugs are administered via the IV or IM route, they enter the extracellular fluid. For IM administration, the drug must diffuse through this fluid to reach the circulation, making hydrophilic drugs more readily absorbed via these routes.
  
• In contrast, medications administered orally or via the S/C route must diffuse through cell membranes to reach the bloodstream. Since cell membranes are composed of phospholipids, lipophilic drugs can pass through them more easily, facilitating their absorption. Understanding these characteristics helps in selecting the appropriate route of administration for optimal drug efficacy. The pH of the drug and the environment can affect absorption because it can affect the drug’s hydrophilic or lipophilic tendencies. Manufacturers sometimes advise that orally administered drugs should be given with food to improve absorption [33].

Factors Affecting Drug Distribution

Some drugs bind more strongly to plasma proteins than others – these are termed highly protein‐bound. The more highly protein‐bound a drug is, the less free drug is available to distribute into the body tissues. The administration of large doses of highly protein‐bound drugs is often necessary to achieve a therapeutic effect. Some drugs bind to the same site on plasma proteins; if these drugs are given together, this may result in the less bound drug not having binding sites leaving elevated amounts of the free drug leading to toxicity; this means that certain medications should not be administered together [33].

The body has natural circulatory barriers these include:

• The blood–brain barrier – the capillary walls in the brain have a different structure from others, which means that only highly lipophilic drugs are able to cross into the brain tissue. Drugs that must reach the brain to have an effect, for example, general anaesthetics, must be sufficiently lipophilic to cross the blood–brain barrier [33, 34].
  
• The placental barrier – the placenta acts as a natural barrier to the foal; the placental barrier, however, is not as efficient at preventing drugs from passing into the foetal circulation, so caution must be exercised when treating pregnant animals.
  
• The testicular barrier – the blood–testis barrier [35, 36], which is created by adjacent Sertoli cells near the basement membrane, serves as a ‘gatekeeper’ to prohibit harmful substances from reaching developing germ cells, most notably post‐meiotic spermatids [34–36]. Like the placental barrier, the blood‐testis barrier is not as effective as the blood–brain barrier, and most drugs can enter if the concentration is high enough [36].

These barriers exist to protect the body from circulatory toxins that may cause the body harm [37].

Tissue perfusion has an effect on absorption rate and speed of distribution. Organ/organs with high perfusion will be able to distribute drugs quickly. In contrast, organ/organs with poor perfusion, although they will receive the drug, will be in a lower concentration and take longer to disperse there due to the drop in the blood plasma. Distribution of a drug follows a concentration gradient; this causes a drug to leave a well‐perfused area, enter back into circulation and enter less well‐perfused areas; this is known as re‐distribution. An example of this is the anaesthetic agent thiopental, which is lipophilic and redistributes to the adipose tissues, causing the animal to regain consciousness. If a horse is suffering from circulatory issues or ischaemia, this should be considered when planning and monitoring medications. Figure 9.4 displays the concentrations of the different routes of administration and how quickly they reach therapeutic levels [33].

The Metabolic Process

All drug eliminations need to be excreted via body fluids. Therefore, all metabolites must be hydrophilic to be eliminated. This happens in two phases [33]: