This study sought to analyze the costs and prescription patterns of anti-glaucoma medicines used in a tertiary hospital in Ghana, a Sub Saharan African (SSA) country. The strength of our study lies in the fact that to the best of our knowledge, there are no published data to review on the drug utilization and cost analysis of anti-glaucoma medications in the ophthalmic department of a tertiary teaching hospital in Africa in general and Ghana in particular
In our study the total number of drugs in the 161 prescriptions was 276. The average number of drugs/prescriptions was 1.71 (~2). This is well within the WHO recommended limit of 2  and falls within the rational use of drugs requirement as stipulated by the WHO. This recommended limit criteria set out by the WHO is an important tool for assessing rationality of prescriptions . Our results are comparable to other studies that had similar averages.
[21 22] but higher in a study reported in India that reported average of 1.49 per prescription  but lower averages compared to the other similar studies [24, 25, 26, 27, 28, 29].
An increase in the number of average drugs per prescription is an important index used to measure an indication for polypharmacy which is associated with an increased risk of drug interactions. This may further lead to unwanted side effects and may also increase prescribing and dispensing errors.
Even though sex did not play any role in glaucoma as illustrated in these studies [2, 30], in our study there were more prescriptions given to female (52.7%%) than male (47.2%) clients. Similar result was reported in another study in Ghana  and other studies in India [32, 33]. This calls for further and most probably larger studies to ascertain the role played by gender among Ghanaian patients with glaucoma.
Drug management of glaucoma commonly includes six classes of drugs: α-adrenergic agonists, β-adrenergic antagonists, cholinergic agonists, prostaglandin analogs and carbonic anhydrase inhibitors and a combination of these groups  .In our study, Prostaglandin analogues were the most prescribed anti glaucoma medicine representing 37% of all the anti-glaucoma medications within this group, with latanoprost as the most prescribed prostaglandin Beta blockers represented 25.4% of the total category of anti-glaucoma medicines prescribed in the study. Amongst the beta blockers, timolol was the most prescribed representing 80% of the total number of beta blockers found in the study,
This is in line with other published literature concerning the use of prostaglandins analogues as a first line of choice in the treatment of glaucoma [35, 36, 37, 38] but in contrast to other studies that were carried out in India where beta blockers most especially timolol was most used [39, 40, 41 42]. The reasons we attribute to the PGA usage as a first line of choice is that it is the drug of choice recommended by Ghana Standard Treatment Guidelines  for the treatment of Glaucoma in Ghana, it is also part of the Ghana Essential Drug List  but unfortunately not included in the list of drugs of the National Health Insurance List (NHIA) which is the list most patients receiving those drugs could have afforded. A look at the cost analysis proved that prostaglandins were far more expensive than beta blockers. This is an indication that all those patients with a prostaglandin prescription will have to pay out of pockets to get their medication. This will create lots of economic constraints to clients especially those with low socio-economic status. It may even lead to non-adherence to treatment which may have a profound effect on treatment prognosis.
Prostaglandin analogues have superseded beta adrenergic blockers as the primary mode of treatment for primary open angle glaucoma because of better patient compliance (it is used once a day whilst other drops are used 2-3 times daily) and lesser adverse effect [46, 47]. Furthermore, Prostaglandin analogues compared to β-blockers have greater efficacy in lowering diurnal and nocturnal IOP with lesser systemic adverse effects [48, 49].
With the carbonic anhydrases, apart from it being the third most prescribed medicine, it is the only group with an oral preparation. Oral acetazolamide accounted for 72.3% of the total number prescribed from this group and brinzolamide (Azopt) accounted for only 27.7%.
It is not surprising to see acetazolamide as the only used oral anti-glaucoma. Topical drugs have proved far effective than oral medications. The rationale for the preference of topical over oral is to minimize systemic side effects. It is a routine practice in this hospital to prescribe oral acetazolamide for a day to a week to three months and then discontinue and replace it with other topical drug if necessary. The rationale given by prescribers is to lower cost. Acetazolamide is prescribed a lot because it is affordable and covered under National Health Insurance Scheme. Most of the patients put on it cannot afford prostaglandins analogues so despite its side effects it still remains useful. It also attains faster reduction of IOP. It is used for short period of time so that chance of acidosis and other side effects like bone marrow depression and renal stone, gastro intestinal disturbances, tinnitus and hypokalemia could be minimized .
In our study, topical carbonic anhydrase inhibitor Brinzolamide was prescribed in (4.0%) of the patient. It was prescribed less frequently as mono therapy possibly because of higher frequency of instillation required (3 times a day) compared to prostaglandin analogs which are instilled once at night and β-blockers mainly timolol prescribed for instillation 2 times daily. It also has higher cost as compared to prostaglandin analogs and β-blockers. These factors are important in considering the compliance in patients with glaucoma which plays an important role in control and prevention of progression of the disease hence its lower usage in the study
Prescriptions for combination therapy were more prevalent compared to prescriptions for monotherapy. This is in line with other studies that indicated that combined therapy yields additive and better results than monotherapy in higher intra ocular pressure (IOP) reduction. . However, combination therapy is given only when the patient requires more than one anti-glaucoma medication. Combination therapy can be with fixed drug combinations (FDC) or concurrent use of more than one anti-glaucoma medication. Most FDC contains a beta blocker. FDC therapy leads to improved compliance and enhance patient convenience, compliance, cost effectiveness and safety.  Our result is comparable to other studies. [42, 40] but demonstrated higher usage compared to other study which didn’t report on usage of FDC therapies .
In our study FDC with beta blockers accounted for 11.2% of the medications for the study. Timolol + brinimodine (combigan) mainly prescribed as a proprietary or branded drug accounted for 64.5% of the study. Apart from lowering the IOP, brimonidine also has neuro protective effect  and also constituted to 8.7% of anti-glaucoma medications in this study. This might have contributed to the prescribers’ choice even though it is expensive. This is in line with other studies that suggested the same drug as the most frequently prescribed FDC  other studies have reported timolol plus dorsolamide [40 ]and timolol plus Bimatoprost as the most used FDC even though in our study they were second and third most frequently used FDC respectively.
Timolol remained the most used beta blocker accounting for 80% of usage in our study. This could be attributed to its low cost of GHC 0.14 per day as well as coverage under National Health Insurance Scheme. This prescription pattern is corroborated by other studies in which it was reported as the frequently prescribed drug .
Similar patterns regarding beta-blocker usage have been reported [42, 39].
Only 1.4% patients were put on miotics or para-sympathomimetic in our study, these were class of drugs that are not preferred now for the management of glaucoma because of the commonly associated side-effects like diminished night vision, reduced visual acuity, opacities, myopia and visual field contraction hence its low patronage by prescribers  and very few studies reported its usage  .There is clear indication of its usage gradually diminishing in the treatment of glaucoma as indicated in our study.
Many drugs were prescribed by generic names (51.1%) in our study. Prescribing under generic name is considered economical and rational. The World Health Organization strongly advocates the practice of prescribing drugs by their generic names . The World Health Organization advocates use of only generic names from national essential medicines list (NEML) for better management . This study also revealed that the percentage of drugs prescribed from Ghana National Essential Drug List was very high almost 100%. The exception are the fixed dose combination therapies.
In our study topical prostaglandins have become a common first-choice glaucoma therapy, partly owing to their relatively consistent clinical efficacy, and also due to their lower frequency of adverse effects. However, topical prostaglandin analogs are expensive, ranging from generic GHC1.18= US$0.26 to GhC1.93 =US$0.42 per day and branded prostaglandin ranged from GHC3.6= US$0.80 to GHC4.9 =US$1.10 per day. The least expensive option for the medical therapy of glaucoma was generic timolol products. This study showed an average cost of GHC0.20=US$0.04 per day compared to the branded timolol (Cusimolol-Alcon) with an average daily cost of GHC 0.59= US$0.13.
Concerning the fact that Ghana is a developing country our cost per day is far lower than what is reported in the western world even as compared to the same branded product .
For example branded prostaglandin (Xalatan) that cost US$0.8 in our study, costs US$1.25 in the USA . In our study, the cost per year for branded brimonidine (Alphagan,) and branded brinzolamide (Azopt) were US$223 and US$527 respectively but in a study conducted in the USA that evaluated yearly cost of glaucoma medications at a University-affiliated teaching hospital with its own health maintenance organization for a three year period (1998 to 2000) , the cost of branded brinzolamide (Azopt) was about half. . This high cost makes the drug very unlikely to be prescribed by ophthalmologists in our setting even though it is a good option.
Finally our study showed that the highest cost of glaucoma treatment per prescription per annum is US$ 420. This is similar to a study done in Ghana  that looked amongst other things at the cost of glaucoma medications.
Our Prices were obtained from the hospital based government facility where prices are heavily subsidized or reduced because of competitive tender processes and also low mark up as compared to private pharmacies and private hospitals where the average cost is likely to be higher.
Prostaglandins remain the most preferred treatment for managing glaucoma by prescribers at the Lions International Eye Centre of the Korle bu Teaching Hospital but are also the most costly followed by Beta blockers. This is in line with Western world literature that chooses prostaglandin analogue over beta blockers [35, 36, 37, 38]. This outcome is also in line with standard treatment guidelines in Ghana but may adversely affect treatment among the poor since prostaglandins are currently not reimbursed in the national health insurance scheme
The Mean age was 58.6±21.2 years with 68.7% information on the ages not available. This percentage of missing values for the age made it difficult for us to compare our study with other age groups in other studies but this is quite similar to the prevalence study that was done at Tema in Ghana .
The study did not account for patients or clients who presented prescriptions to the pharmacy but did not purchase the prescribed drug as well as those who presented prescriptions but could not be served due to unavailability of the drops at the pharmacy. Such clients would usually take their prescriptions away.
These findings cannot be generalized as prescribing preferences may vary from one hospital to another in the absence of a national treatment guideline for glaucoma diseases. However, being a national training centre for most ophthalmologists in Ghana, the results may be a true representation of prescribing pattern for glaucoma medication in Ghana
Further, the study did not provide the type of glaucoma treated as this was not available on the prescription.