Drugs used to help prevent CH occurring in the first place are called prophylactics or preventative treatments. The aim of preventative treatment is to attempt to reduce the number of attacks with minimal side effects until the cluster bout is over in ECH, or for a longer period in CCH. There are two types of preventative treatments: -
1. Short term preventatives - designed for quickly controlling the attack frequency but not suitable for long term use.
2. Long term preventatives - designed for long term management of CH.
SHORT TERM PREVENTION
Short term prevention tends to be better amongst sufferers who have either short bouts (perhaps in weeks rather than months) or for sufferers where it is necessary to quickly control the frequency of attacks. These drugs cannot be used in the long term because of the potential side effects.
The most effective and fast acting steroids are called corticosteroids. However, careful monitoring of the sufferer is necessary because of the potential for serious side effects. Treatments are normally limited to between 2-3 weeks whereby the amount of drug taken over this period is reduced over time. The tablets, called prednisolone (1mg per kg), are prescribed starting at a maximum dosage of 60mg once a day for five days, and from then on, a decreased dosage (by 10mg) every three days. Unfortunately, this necessary 'tapering' effect (reducing the dosage) means that in most sufferers the CH returns, and for this reason, steroids are only used as a first-step treatment alongside other preventatives until these become effective, or to give chronic sufferers or those with long bouts, a necessary respite for a short time.
This drug has now been withdrawn by the manufacturer.
Ergotamine is very useful in the short-term prevention of those attacks that predictably occur at the same time of day and night. It can be prescribed as a tablet or a suppository (1-2mg) and is taken either at bedtime or about an hour before an attack is due. It is rarely suitable for CCH sufferers. It is not recommended that ergotamine is taken at the same time as sumatriptan. this drug is now very rarely used in the treatment of cluster headache.
This treatment is only available at particular hospitals who have access to supplies from overseas. The drug is no longer available in the British Pharmacopoeia for general prescription. Given by parenteral infusions in hospital over five days. Used mainly for relief for chronic sufferers who do not respond to other preventives.
LONG TERM PREVENTION
Some ECH sufferers (those with particularly long bouts) and CCH sufferers require preventative treatment over many months or even years. The two most favoured long-term drugs are verapamil and lithium.
Verapamil is currently the most preferred drug amongst sufferers of both ECH and CCH. Medical research has shown that higher doses are needed than for other uses of the drug. Dosages of the drug vary from between 240mg to 960mg per day, normally taken in tablet form three times a day. The strength of the tablet is increased every two weeks until it is effective in stopping cluster attacks or until the maximum dose of 960mg per day is reached.
However, verapamil can have side effects including 'heart block' (a block in the conduction of the normal impulses of the heart). It is therefore mandatory that individuals are given an ECG before taking the drug, and then again, each time the dose is increased to check for any potential abnormalities.
Lithium is effective as a preventative amongst many sufferers, more so amongst CCH. Kidney and thyroid tests are required prior to prescribing the drug. Sufferers are then started on 300mg tablets twice a day and the amount of the drug in the body is then monitored until it reaches the desired medical concentration in the body as outlined in the BNF (British National Formulary). Many sufferers benefit at levels between 600-1200mg per day. It is not recommended that lithium is taken at the same time as non-steroidal anti-inflammatory drugs, diuretics or carbamazepine. Users will need to carry a card stating they are on lithium as it is contra-indicated with some other treatments and an emergency department would need to know this in the event of an accident.
3. Other Drugs
Other frequently used drugs used for preventative treatment include sodium valproate, pizotifen, topiramate, gabapentin and melatonin. The effectiveness for these, however, is as yet medically unproven.