Safe administration of parenteral medications: Routine injections in general practice. Part 2
In addition to the host of childhood and other immunisations that practice nurses administer, they are frequently called upon to give other medications by injection. In Part 2 of our series, we look at commonly given hormonal injections and drugs used in mental health conditions
In the first article in our series looking at parenterally administered medications that are given by practice nurses, we focused on the administration of some of the more commonly given drugs that are used to treat, modify or stabilise a condition, provide replacement of lacking elements or are given to prevent conditions. The second part will focus on hormonal injections and the injectable medications used in the treatment of mental health conditions, specifically:
- Depot contraceptives
- Testosterone replacement therapy
- Gonadotrophin-releasing hormone analogues (GnRHa)
- Long acting antipsychotic medications
As with the administration of any medicine regardless of the route it is delivered, all registered nurses should work within the NMC Code1 and follow the NMC standards for medicines management,2 which state 'as a professional, you are personally accountable for actions and omissions in your practice, and must always be able to justify your decisions'1 and 'you must know the therapeutic uses of the medicine to be administered, its normal dosage, side effects, precautions and contra-indications.'2 Hence it is essential the practice nurse keeps herself up to date with current changes in guidelines and policy and, administering medication under patient group directions (PGDs), to ensure that these are kept accurate and current.
DEPOT CONTRACEPTION
Depo-Provera®
Depo-Provera contains medroxyprogesterone acetate, a form of progesterone. It is used as a long-acting contraceptive that once administered leaves a pool of medroxyprogesterone in the muscle which is gradually released over a period of 12 weeks.
Depo-Provera works in three ways, by:
- Preventing ovulation
- Increasing the thickness of the natural cervical mucous
- Rendering the endometrium less receptive to implantation
The initial dose of 150mg Depo-Provera is given by deep intramuscular injection into the gluteus maximus muscle using the Z-track method (Figure 1) within the first five days of the menstrual cycle, when it will provide immediate contraceptive cover. It can be given at other times in the cycle but an additional method of contraception will be needed for 7 days. Injections are repeated every 12 weeks and must be given before 5 days after this time.
Post partum, the injection can be administered within 5 days of delivery if the patient is not breast feeding; however, there can be prolonged and heavy bleeding about which the patient must be counselled before administration. In breast feeding patients, the injection cannot be given until 6 weeks post partum. If for any reason the interval between injections is more than 12 weeks and five days, pregnancy should first be excluded, and if Depo-Provera is then given, an additional contraception must be used for the first 14 days.3
If switching from one hormonal contraception to another, then a regime that provides continuous cover should be employed e.g. if using oral contraception the injection should be given within 7 days of taking the last active pill.
Effective counselling about potential adverse effects should be provided for any women wishing to consider Depo-Provera. This should include possible bleeding irregularities, weight gain, delayed return to fertility and effects on bone mineral density (BMD).
Menstrual irregularities are common and may include either amenorrhoea or heavy and prolonged bleeding (Table 1).
Weight gain affects up to 1% of patients. Women may experience a 2.25 — 3.5kg (5-8lb) weight gain within the first 12- 24 months of use. This gain increases with prolonged use, so advice on weight management should be considered as part of a holistic consultation.
The practice nurse should be aware that Depo-Provera decreases oestrogen levels, which with time can lead to loss of BMD — particular attention should be paid to adolescents and young women whose bones may be immature, with regular re-evaluation of the risks and benefits being undertaken at least every two years, and specifically focusing on osteoporosis prevention, with advice on dietary calcium and vitamin D as necessary. Groups at increased risk of osteoporosis are shown in Box 1.
Further information related to return of fertility, cancer risks and thromboembolic disorders can be found in the summary of product characteristics.
TESTOSTERONE REPLACEMENT THERAPY
Testosterone propionate (Virormone®), testosterone undecanoate (Nebido®), testosterone (combination of esters) (Sustanon®)
Testosterone is an androgen produced naturally by males in the testes. It is essential for normal growth, the development of male sex organs and secondary sexual characteristics. Replacement therapy may be required in either congenital or acquired conditions resulting in primary or secondary hypogonadism (testosterone deficiency syndrome). It may also be administered for supportive therapy in female to male transsexuals. Some forms of testosterone also have a license for female breast cancer. In general, the dose and frequency of administration are adjusted according to the individual patient's response,4 which should be carefully monitored by serum testosterone levels and changes in characteristics.
Testosterone supplementation can increase the risk of benign prostatic enlargement or prostate cancers in males, so regular monitoring of prostate specific antigen (PSA) and yearly digital rectal examination (DRE) are recommended. The practice nurse should ensure these checks are performed as part of the ongoing treatment plan.
There are many contra-indications to testosterone injections as well as the potential for many side effects; therefore the practice nurse should have a discussion with the patient at each consultation to explore any new medical conditions arising since the last visit or any new side effects that could be attributable to treatment.
Testosterone supplements are available in different forms — gels, patches as well as injectable preparations, including testosterone proprionate (Virormone®), testosterone undecanoate (Nebido®), testosterone enantate or as a combination of esters (Sustanon®). All injections are administered by deep intramuscular injection where it forms a reservoir in the muscle and is gradually released. (Figure 1) However, there are some differences in technique that should be adhered to if administering these medications. Testosterone propionate (Virormone®) can be given as any other intramuscular injection as it is not in an oily base. However, Testosterone enantate, Sustanon® and Nebido® are all in oil bases, and as with any oil based injections extra care should be taken checking for any oil allergies (oils such as arachis oil and castor oil are used). It is essential to check, by aspirating, that the needle is not in a vein before the medication is administered to avoid emboli.
Estosterone undecanoate (Nebido®) is administered every three months and care should be taken to administer it as per the manufacturer's recommendation, very slowly, over two minutes, deep into the gluteal muscle.
Other forms of testosterone injections are given over varying time periods dependent on the condition being treated, and for female to male transsexuals the frequency is determined by the treatment centre.4
GONADOTROPHIN-RELEASING HORMONE ANALOGUES
Goserelin (Zoladex®), leuprorelin (Prostap®)
Goserelin and leuprorelin are gonadotrophin-releasing hormone analogues (GnRHa) that act on the pituitary gland. The pituitary gland produces and stores luteinising hormone (LH) and follicle stimulating hormone (FSH). In males LH causes the testes to produce testosterone, which together with FSH causes the testes to produce sperm. In females FSH and LH cause the ovaries to produce oestrogen and control the menstrual cycle. The process by which the pituitary controls FSH and LH release is regulated by the luteinising hormone releasing hormone (LHRH) gonaderelin.
Both goserelin and leuprorelin are synthetic forms of gonaderelin, and act on the LHRH receptors in the same way as the natural form. Being able to influence these receptors can help in many conditions that are mediated by FSH and LH, and control the amounts of oestrogen or testosterone that are produced.
Goserelin is used in male patients for prostate cancer and in female patients for endometriosis, some oestrogen receptor positive breast cancers, fibroids, endometrial thinning and, at times, in assisted reproduction. Leuprorelin does not have a license for breast cancer or in assisted reproduction.
Both injections come in two strengths, either given every 28 days or every 3 months.
Goserelin 3.6mg, given every 28 days, may be used for all conditions for which it is indicated, and the 10.8mg dose,given every three months, is reserved for male patients only.
Leuprorelin 3.75mg, given every 28 days, can be used for all licensed indications and the 11.25mg dose, given every 3 months, is used in the treatment of prostate cancer and endometriosis.
The duration of treatment for different conditions also varies (Table 2).
When GnRHa therapy is first initiated in men with prostate cancer, it can cause a tumour flare, which in turn may increase prostatic symptoms or cause spinal cord compression. It is therefore important that the patient is advised to report any urinary obstruction symptoms, changes in control of the bladder or bowel or any neurological symptoms. Developing diabetes, worsening hyperglycaemic control and increased cardiovascular risks have been also been reported in men.
In female patients there can also be an initial flare period in the first few days after administration, causing an exacerbation of symptoms, and oestrogen withdrawal bleeding may occur. It is essential that a non hormonal method of contraception is used during treatment as LHRH agonists present a theoretical risk of abortion or foetal abnormality. Breast feeding should be avoided.
The practice nurse should be aware that GnRHa therapy may decrease bone density in both male and female patients, by between 2.4% & 15%.6.9 Strategies to reduce this effect have been attempted, but with little success,10,11 therefore dietary and falls prevention advice should be offered.
Common side effects (affecting 10-20% of patients) include vasomotor effects (hot flushes), insomnia, irritability, depression, headaches, loss of libido, vaginal dryness and joint stiffness.10
Goserelin is administered subcutaneously into the anterior abdominal wall using an aseptic technique. The needle should be inserted at 30-45% to the skin with the needle bevel pointed upwards. Full instructions on administration can be found in the product information leaflet.
Leuprorelin 3.75mg is administered by either a subcutaneous or intramuscular injection (Figure 1). The 11.25mg injection is administered as a subcutaneous injection for prostate cancer, but by intramuscular injection for endometriosis.6
Subcutaneous (SC) injections
For a SC injection, the skin should be bunched up and the needle inserted at a 45º angle to the skin. There is no need to aspirate and gentle pressure should be administered if required.
LONG ACTING DEPOT ANTIPSYCHOTIC (LAI) MEDICATIONS
Flupentixol decanoate (Depixol®), Zuclopenthixol decanoate (Clopixol®), Risperidone (Risperdal Costa®), Fluphenazine decanote (Modecate®)
These antipsychotic medications are used in the treatment of schizophrenia and other psychotic illnesses that are thought to be caused by the over activity of dopamine in the brain, and work by blocking the dopamine receptors. Risperidone, a second generation LAI also has the benefit of affecting the neurotransmitter serotonin, thus also relieving the negative symptoms of schizophrenia such as lack of emotion and social withdrawal. The advantages and disadvantages of depot antipsychotic drug administration are shown in Table 3.
The choice and dosage of LAI is dependent on the individual patient's symptoms, and treatment will be tailored according to the individual's treatment plan.13 The administration technique also needs to be appropriate to the drugs that has been prescribed, particularly as many of the injectable antipsychotic drugs are oil based.
Risperidone (not oil based) is licensed to be administered by deep intramuscular injection into either the deltoid or gluteal muscle and should be administered with the Needle-Pro safety needle supplied.
Flupentixol deconaote, zuclopenthixol deconoate and fluphenazine decanote are all oil-based injections given intramuscularly (see Figure1) and require special consideration. It is essential to check for allergies before these medications are administered to protect both the patient and the administrator as differing oil bases are used, including sesame and coconut.
Consideration should be given to the length of the needle used to allow administration of the medication into the muscle. Nisbet14 suggests a 35mm needle may not be long enough to reach muscle, especially in females who have a deeper fat layer at the dorsogluteal site. Prior to administration, it is essential to ensure (by aspiration) that intravascular administration does not take place.
There are many drug interactions and potential adverse effects associated with antipsychotic medications, including the risk of self harm and suicidal ideation, and these should be discussed openly with the patient. For further information about interactions and adverse effects, consult the British National Formulary (BNF) and the summary of product characteristics (SPC) for the individual medication.
LAIs should be avoided in pregnancy unless the benefits to the mother outweigh the risks to the baby, but there is the potential for low apgar scores and withdrawal effects at delivery. Breast-feeding should be avoided.
CONCLUSION
All registered nurses have a responsibility to ensure they maintain their professional competency and practise within the limitations of their competency. Regular review of the evidence supporting medication use and information sources such as the BNF or SPCs ensures practice is always current and up to date. Using a systematic approach and adopting safe practice principles, as with all drug administration, will help to ensure a good patient experience and reduce the potential for drug errors.
REFERENCES
1.Nursing & Midwifery Council .The code: Standards of conduct, performance and ethics for nurses and midwives. London: Nursing & Midwifery Council; 2008
2.Nursing and Midwifery Council Standards for medicines management. London: Nursing & Midwifery Council; 2010
3. Summary of Product Characteristics Depo-Provera (2013). Available at: http://www.medicines.org.uk
4. . Summary of Product Characteristics Sustanon (2013). Available at: http://www.medicines.org.uk
5. . Summary of Product Characteristics Goserelin (2013). Available at: http://www.medicines.org.uk
6. . Summary of Product Characteristics Leupropelin (2013). Available at: http://www.medicines.org.uk
7. Macmillan. Goserelin for breast cancer available at: http://www.macmillan.org.uk/Cancerinformation/Cancertreatment/Treatmenttypes/Hormonaltherapies/Individualhormonaltherapies/GoserelinBreast.aspx#DynamicJumpMenuManager_6_Anchor_5
8. Macmillan (2013) Goserelin for prostate cancer available at: http://www.macmillan.org.uk/Cancerinformation/Cancertreatment/Treatmenttypes/Hormonaltherapies/Individualhormonaltherapies/GoserelinProstate.aspx
9. Astra Zeneca (2013) Zoladex. Available: http://www1.astrazeneca-us.com/pi/zoladex3_6.pdf
10. Kennedy S, Moore J. Chronic pelvic pain. In: Waller, D. and McPherson, A. (Eds.) Women's Health. 5th edn. Oxford: Oxford University Press, 2003; 399-420
11. Fogelman I, Blake GM, Blamey R, Palmer M, Sauerbrei W, Schumacher M, Serin D, Stewart A, Wilpshaar W (2003) Bone mineral density in premenopausal women treated for node-positive early breast cancer with 2 years of goserelin or 6 months of cyclophosphamide, methotrexate and 5-fluorouracil (CMF). Osteoporosis International. 2003;14(12):1001-6
12. Diggle L. Injection technique for immunisation. Practice Nurse 2007;33(1)
13. Royal College of Nursing. Mental health Practice - Administration of depot and long acting antipsychotic injections. Middlesex: RCN Publishing; 2008
14. Nisbet A. Intramuscular gluteal injections in the increasingly obese population: retrospective study. BMJ 2006; 332: 637-638.
