Pharmaceutical care - Patient profile

The patient had low sodium levels after the TURP was performed. Regular sodium chloride tablets were prescribed to correct this deficiency, as the patient was symptomatic. These tablets were discontinued once he was asymptomatic despite his Na levels being 132.

The patient has very low haemoglobin results. Haemoglobin is responsible for transporting oxygen in red blood cells. The patient had a consistently low result throughout his stay in hospital.

The patient's platelet count is slightly elevated. It is possible that the patient has a chronic infection.

The patient's creatinine clearance on day 1 was:

(140 - 81) x 1.23 x 65 = 33.45 mls/min

141

The creatinine clearance was calculated retrospectively as the Cockcroft and Gault equation should only be used if the serum creatinine concentrations are consistent. The patient has normal to acutely impaired renal function. Hence the renal function was monitored closely.

PHARMACEUTICAL PROBLEMS

MEDICAL PROBLEM

PHARMACEUTICAL PROBLEM

BACTERIAL INFECTION

MANAGEMENT OF INFECTION

ATRIAL FIBRILLATION (AF)

MANAGEMENT OF AF

BORDERLINE RENAL FUNCTION

DRUG HANDLING IN MILD RENAL IMPAIRMENT

SOAP NOTES

PHARMACEUTICAL PROBLEM:

Management of Atrial fibrillation post TURP.

SUBJECTIVE

The patient had palpitations and felt generally unwell.

OBJECTIVE

The patient's pulse rate was elevated on average 100 (highest 150) at rest.

The patient's ECG showed no P waves and an irregular baseline.

ANALYSIS

The patient developed fast atrial fibrillation following the TURP. To control the atrial fibrillation he was given digoxin. Digoxin was given as it increases the force of contraction of the heart and reduces conductivity within the atrioventricular node.

The loading dose for digoxin was calculated using the following information: Weight: 65kg Creatinine: 141 Age: 81

Creatinine Clearance: 1.23x(140-age)xweight = 1.23x59x65 Serum Creatinine 141

= 33.45mls/min

Volume of distribution: 3.12CrCl + 3.84weight (Vd) 3.12(33.45) + 3.84 (65) = 353.96 litres

Loading Dose: Cpdes.Vd S.F

1.5 x 353.96 = 856 micrograms 1 x0.62

Hence a loading dose of 1 milligram would be suitable. The loading can be given as two doses of 500 microgram tablets given six hours apart.

A predicted digoxin level can be determined using the following equation:

Cpdes= DosexSxF = 1000x0.62x1 = 1.75 ?g/Litre. Vd 353.96

The accepted therapeutic range for digoxin is 1 to 2 ng/ml. Hence the loading dose of 1 milligram will give a serum concentration of 1.75 ?g/ml, which is within the therapeutic range.

The maintenance dose can also be determined using the following equations:

Clearance: 0.06Creatinine Clearance + 0.02Weight 0.06x141+0.02x65 = 9.76 litres/hour

Maintenance Dose: Clearance x Cpss x ? SxF

234.24 L/day x 1.5 microgram/Lx1day 1.0 x 0.62

= 566.7 micrograms/day

Hence 500 micrograms daily would provide a serum concentration of 1.5 ?g/L. However because of the patient's mild renal impairment a dose reduction is required.

According to the Renal Drug handbook, in mild renal impairment the dose range of digoxin that can be used is 125 to 250 micrograms. Instead based on the patient's impaired renal impairment and age 125 micrograms daily was prescribed.

Digoxin is a drug with a narrow therapeutic range therefore therapeutic drug monitoring is required to ensure that the serum drug levels are within the therapeutic range. A level was determined 8 hours after the fourth dose (i.e second maintenance dose), a level of 1.2 ng/ml was determined. I had to explain to the prescribing doctor that it takes at least 7 to 14 days for the drug to reach steady state, hence the level obtained is not particularly useful. Instead another level should be taken on day 9 to check that the serum drug concentration is within the therapeutic range.

The patient's digoxin therapy was stopped however on day 17. This is because the prescribing doctor was concerned that the patient's pulse still averaged 95 beats per a minute at rest. I did advise the doctor that the drug had not quite reached steady state yet and the ideal dose would be 250 micrograms daily. Despite my concerns the prescribing doctor was more inclined to use a Beta blocker. The patient was then loaded up on metoprolol in my absence. While the patient was receiving metoprolol 50mg tds, his blood pressure plummeted to 80/44. Concerned by this I contacted the prescribing doctor and urged her to discontinue the metoprolol on the basis that the patient's blood pressure had fallen to an unacceptable reading. The patient's baseline blood pressure on admission to the ward was 100/80 on average. The doctor however was adamant that the patient's rate was being well controlled with the metoprolol (average 80 beats per minute). Following this conversation the doctor liased with their consultant and a decision was made to stop the metoprolol and start amiodarone.

PLAN:

Monitor blood pressure daily.

Monitor pulse daily.

Monitor the patient's renal function.

Monitor the patient's weight, potassium levels and renal function while receiving digoxin therapy.

SUMMARY OF THE PHARMACISTS CONTRIBUTION:

PROBLEM

CONTRIBUTION

OUTCOME

Digoxin level (timing)

Doctors told to take a sample on day 9 and explained how therapeutic effect was related to steady state concentration of drug.

Therapy stopped by another doctor, hence true level not determined.

Loading dose and maintenance dose of digoxin

Calculated doses required to produce the desired serum drug concentrations.

Doses used based on calculations rather than guesses.

Low blood pressure while on metoprolol 50mg tds

Advised the doctors to stop the metoprolol, when blood pressure fell below patient's baseline blood pressure. BPs recorded were 80/44, 70/46 etc

On stopping the metoprolol the BP recovered and rose to 100/80,110/78 etc

REFLECTIVE ACCOUNT:

I am more confident in dealing with patients who are being started on digoxin therapy. This is mainly due to the pharmacokinetics workshop, which clearly explained the calculations used to determine the loading and maintenance doses etc. I was particularly impressed with my intervention, when the patient was receiving metoprolol 50mg tds and his blood pressure fell very low. I always kept a close eye on the medications being prescribed as when the patient was admitted he was on no regular medicines. He seemed to be daunted by the prospect of taking so many medicines. I regularly counselled the patient on the medicines being prescribed. When the patient was started on dalteparin 13,000 units daily by haematology, I advised the doctor to monitor the Factor Xa levels as this patient had mild renal impairment and hence it would be more difficult for him to excrete the drug. His calcium levels also began to decrease quite quickly, once corrected, his calcium levels were below the lower limit. I again suggested that more frequent calcium levels be performed before commencing treatment to supplement his calcium. Unfortunately on starting my next rotation I was told that the patient had died, after his stats continued to fall (i.e albumin, pulse rate continued to be erratic,) and a tumour had been located on one of his kidneys. This is the first patient I have looked after who has died. I was upset because at one point he seemed to be improving and returned to his usual jolly self.

SUMMATIVE PATIENT MEDICATION PROFILE

Medicine

Mode of Action

Indication

Efficacy/Safety Parameters

Counselling Points

Metoprolol

Beta-blocker. Metoprolol is used to treat high blood pressure as well as controlling how quickly your heart beats. It works by relaxing blood vessels so the heart doesn't have to pump as hard.

Atrial fibrillation

* dizziness

* lightheadedness

* excessive tiredness

* cold hands and feet

Cardioprotective properties

To be taken regularly. Do not stop taking unless advised by your doctor.

Digoxin

Controls the rate at which your hearts contract and hence should stop the palpations you are experiencing.

Atrial Fibrillation

Report promptly:

Visual disturbances, weight loss or loss of appetite, nausea vomiting or tremor.

Do not stop taking without medical advice.

Venita Hardweir Page 1 13/08/2004